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I've been playing Battlefleet Gothic: Armada recently and in the course of reading up on the Imperial Navy, I couldn't really find any firm numbers of the size of Imperial Fleets. Indeed the one fact I did come across was that in the Segmentum Obscurus alone (1 out of the 5) there were only 600 Lunar Class Cruisers, which were meant to be the most numerous of Cruiser designs. So, onto a little maths, bearing in mind that this is all extrapolation on my part:

If the Segmentum Obscurus has 600 Cruisers, then being roughly the same size as Solar and Pacificus combined, the same size as Tempestus and half the size of Ultima that would nominally put total Imperial Cruisers at around 3000 Cruisers.

Fair enough. However, here's where I start to get a little disbelieving:

A Space Marine Strike Cruiser is equipped to hold one full SM company. A Battle Barge can hold up to 3 companies. So assuming these numbers to be correct, a full SM Legion of circa 100,000 Marines would require either 333 Battle Barges or 1000 Strike Cruisers, or more likely a combination of the two, to carry the Legion to battle. So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH (Even if split up into warbands or replaced with similar vessels), then the Traitor Legions alone can muster up to 9000 Cruiser class vessels.

It seems therefore, that the Traitor Legions alone can muster three times as many Cruisers as the whole Imperium, without even taking into account the many billions of traitors and renegades in the Lost and the Damned and the thousands more vessels they can muster.

That's got to be wrong, so what would be a more reasonable estimate of the Imperium's naval strength?

Many of the old battle barges are under staffed. By a good margin.
Enternal crusader has a capacity of 600...

It has entire unused decks and bays. It could carry higher than 600, likewise 300 is merely the deployable number. If needed they can garrison higher just not simultaneously deploy, though design means eternal crusader can deploy 600. But I is a GC era and also 10km and larger than most battleships in production or battle barges.

The phalanx has entirely unused wings and could carry a entire chapter easily, easily!
Probbly least 5.

And I think those naval estimate for imperium is low.
Someone's low balled there.

Segmant solar probbly has a few hundred on its own defending it.

So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH

Thats a big assumption though. It would be reasonable to assume they lost a lot of ships during the scouring and the13 black crusades.
Whether those losses were actually replaced en masse cant be said with certainty.
And thats not to mention their run ins with Eldar, Orks or other factions throughout time.

jhe90 wrote:Many of the old battle barges are under staffed. By a good margin.
Enternal crusader has a capacity of 600...

It has entire unused decks and bays. It could carry higher than 600, likewise 300 is merely the deployable number. If needed they can garrison higher just not simultaneously deploy, though design means eternal crusader can deploy 600. But I is a GC era and also 10km and larger than most battleships in production or battle barges.

The phalanx has entirely unused wings and could carry a entire chapter easily, easily!
Probbly least 5.

And I think those naval estimate for imperium is low.
Someone's low balled there.

Segmant solar probbly has a few hundred on its own defending it.

It's worth noting that the Eternal Crusader is considered to be much modified in comparison to a standard Battle Barge - and hence it can accommodate more troops. However, I still doubt that a Battle Barge can comfortably accommodate more than 300 Marines. Obviously if you really needed to, you could pack a good few thousand SMs into a Battle Barge if they were really crammed in, as in the case of the evacuation from Isstvan V, because it's a 5km long vessel. However, in terms of practical deployment and as an operating base, the number would be far less becasue you've got to fit in vehicles, supplies, fuel, aircraft not to mention the tens of thousands of additional Serfs and Equerries that are not part of the ship's complement, but are still needed to maintain the SM Companies.

Ratius wrote:

So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH

Thats a big assumption though. It would be reasonable to assume they lost a lot of ships during the scouring and the13 black crusades.
Whether those losses were actually replaced en masse cant be said with certainty.
And thats not to mention their run ins with Eldar, Orks or other factions throughout time.

I'll agree it is a big assumption, which is why I said 'roughly'. That said, I think they'll have maintained a decent enough arsenal due to their constand raids on Imperial shipping alongside 10,000 years worth of defecting captains and even the assimilation of renegade or excommunicated 'modern' SMs.

It just seems like such an incredibly low number for there to only be 3000 Cruisers defending a whole Galaxy, especially when we all know the vast size of the Galaxy and the billions of worlds it can hold.

I agree that there would have to be a lot more than just 3000 Cruisers.

Just taking into account the amount of men and equipment that the guard have to move around would necessitate way more than that.

I take that with the same grain of salt i take any hard number given about Imperial manpower or forces. Basically, as far as i'm concerned the Imperium hasn't the faintest clue how many of anything they have, given the vast quantities of stuff they have to keep track of and the colossally inefficient bureaucracy they have for a government.

It's one thing i use to get around the fact that uf the official numbers were reliable the amount of Space Marines in the galaxy would be pitifully insignificant and quite frankly barely sufficient to conquer even a moderately defended planet.

9000 cruisers for the traitor legions honestly isn't that unlikely. the blood angels maintain a force of 2 Battle Barges and 7 strike cruisers, the Ultramarines 3 Battle Barges and 8 strike cruisers. these are first founding chapters, yes, but as they're planet based not fleet based, we can PROABLY safely use them as a comparison.

assuming thus these numbers are average, you're looking at an estimated fleet strength of approximatly 10 thousand line ships for the Astartes.

Yea the use of numbers within the 40k background is a bit inconsistant.

In Codex: Armageddon it says that the standing fleet assets of the Armageddon System at the start of the third war were 7 cruiser squadrons and two Apocalypse class battleships.
One week later the Ork fleet in the system numbered 2000 ships (tonnage unspecified) including 12 Space Hulks.

Now Armageddon is supposed to be one of the best defended worlds in the Imperium and Waaagh Ghazgull one of the largest Ork Waaaghs ever seen.
If the forces of Chaos can gather a fleet of 9000 cruisers, it would represent a fleet of absolutely staggering power in the background!

Each battlefleet consists of 50 to 75 warships of varying size, although in some sectors this will more or less, according to the importance of the sector and the number of enemies it must contend with. As well as these destroyers, frigates, cruisers, and battleships...

p. 86, Battlefleet Gothic rulebook

The above is for a typical sector's fleet and this number includes escorts, not just capital ships (i.e. cruisers and larger). The average sector is a 200 light year cube, encompassing many systems.

The Armageddon system is atypical, due to its importance. A squadron in BFG is 2-6 ships so 7 cruiser squadrons is 14-21 cruisers already.

Massed fleets and apocalyptic fleet actions are actually uncommon, though disproportionately focused on.

There may be 600 lunar class in a segmentum fleet, and there may be no more than 600 of any other given classes, but the navy have a lot of different classes with several hundred of each. The lunar is the most common class of navy capital ship. Thats not the same as saying a majority of ships are lunar class.

Even assuming the segmentum has only 2-300 of each of the following, off the top of my head, there are:

- Gothic class
- Tyrant class
- Dominator class
- Dictator class
- Defiance class
- Endeavour class
- Endurance class
- Dauntless class
- Siluria class

If a segmentum fleet has only a couple of hundred of each class, that's 2,000 per segmentum - and thats not including more obscure cruiser classes I can't remember, and battleships, battlecruisers and grand cruisers, of which there are at least half a dozen known classes of each, and which the navy fleet list suggests tend to turn up at between 1 per 2 other cruisers and 1 per 4 other cruisers.

This also doesnt include Rogue Trader fleets and Black Ships, which whilst not Navy vessels tend to be of cruiser or battleship displacement, and Adeptus Astartes and Adeptus Mechanicus, who maintain all-up warfleets of their own.

WH40K has zero sense of scale. It's got hive worlds with populations in the trillions, but 3000 ships per sector? Literally over a million worlds controlled by humanity, but less than 15000 ships in the navy? The Imperial Navy should number in the millions of ships, especially given how unreliable warp travel is - which is to say you can't count on a large percentage of the ships to be available at any one time, because warp travel takes however long the warp feels like.

Never mind that the Navy has to transport the Army, which is basically uncountable.

locarno24 wrote:
There may be 600 lunar class in a segmentum fleet, and there may be no more than 600 of any other given classes, but the navy have a lot of different classes with several hundred of each. The lunar is the most common class of navy capital ship. Thats not the same as saying a majority of ships are lunar class.

Even assuming the segmentum has only 2-300 of each of the following, off the top of my head, there are:

- Gothic class
- Tyrant class
- Dominator class
- Dictator class
- Defiance class
- Endeavour class
- Endurance class
- Dauntless class
- Siluria class

If a segmentum fleet has only a couple of hundred of each class, that's 2,000 per segmentum - and thats not including more obscure cruiser classes I can't remember, and battleships, battlecruisers and grand cruisers, of which there are at least half a dozen known classes of each, and which the navy fleet list suggests tend to turn up at between 1 per 2 other cruisers and 1 per 4 other cruisers.

This also doesnt include Rogue Trader fleets and Black Ships, which whilst not Navy vessels tend to be of cruiser or battleship displacement, and Adeptus Astartes and Adeptus Mechanicus, who maintain all-up warfleets of their own.

Also the inquisition may have some ships, witch hunters and the like need transport.
There's also armed merchant ships, which whole not full warships can defend against lower level pirates, minor skirmishes and be drafted in times of desperate need.

There might be thousands of armed Merchants in a sector, mostly on set routes but still on the list.

Trycky as GW varies the numebrs all the time

So at one time the Space Wolves had a single battleship that they used as a Battlebarge. In the 7th Editoin codex they had about 300 ships (!) and several Star Fotresses - all of which makes no sense when they also reduced the size of the Chapter. In the same edition, the Black Templars dropped massively in size but are now back to tens of thousands.

The Navy again varies massively depending on which fluff source you use.

 Warpig1815 wrote:
I've been playing Battlefleet Gothic: Armada recently and in the course of reading up on the Imperial Navy, I couldn't really find any firm numbers of the size of Imperial Fleets. Indeed the one fact I did come across was that in the Segmentum Obscurus alone (1 out of the 5) there were only 600 Lunar Class Cruisers, which were meant to be the most numerous of Cruiser designs. So, onto a little maths, bearing in mind that this is all extrapolation on my part:

If the Segmentum Obscurus has 600 Cruisers, then being roughly the same size as Solar and Pacificus combined, the same size as Tempestus and half the size of Ultima that would nominally put total Imperial Cruisers at around 3000 Cruisers.

Fair enough. However, here's where I start to get a little disbelieving:

A Space Marine Strike Cruiser is equipped to hold one full SM company. A Battle Barge can hold up to 3 companies. So assuming these numbers to be correct, a full SM Legion of circa 100,000 Marines would require either 333 Battle Barges or 1000 Strike Cruisers, or more likely a combination of the two, to carry the Legion to battle. So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH (Even if split up into warbands or replaced with similar vessels), then the Traitor Legions alone can muster up to 9000 Cruiser class vessels.

It seems therefore, that the Traitor Legions alone can muster three times as many Cruisers as the whole Imperium, without even taking into account the many billions of traitors and renegades in the Lost and the Damned and the thousands more vessels they can muster.

That's got to be wrong, so what would be a more reasonable estimate of the Imperium's naval strength?

That seems indeed wrong. Firstly because the Legions were not just limited to strike cruisers and battle barges (they had much larger ships). Also, even in 40k, battle barges can be of wildly varying size. 'Battle barge' is not the name of a standardised ship class or such, it is simply a designation for any large warship owned by a Space Marine chapter. Entire Chapters are based out of a single battle barge, indicating some can carry far more than 3 companies.
Secondly, the estimate is wrong because after the Heresy and the Scouring, no SM Legion had numbers even close to 100,000.
Thirdly, it seems wrong because in the more than 10,000 years of war that seperate the end of the Scouring and 'present-day' 40k, the vast majority of traitor legion assets will have been destroyed in the endless campaigns against the Imperium, with only few opportunities for replacement.
And last but not least, there are as many cruisers as the plot demands. The amount of cruiser classes that exist is unknown. If they run out of Lunar-Class cruisers, the writers will just invent a new class.

Since we're talking about fleets, does lore ever state what the fate of the Emperor's personal battleship, the Bucephalus is?

The numbers of the Imperial navy are not hard and fast. But we can make some educated guesses going by the official numbers.

http://wh40k.lexicanum.com/wiki/Battlefleet

A Battlefleet is the basic unit of the Imperial navy. Consisting of between 50-75 ships on average. Lets say 20% of the ships are battleships, 30% are Cruisers, and 50% are escort vessels.

Every Sector has it's own Battlefleet.

http://wh40k.lexicanum.com/wiki/Sector

A sector is a unit of volume, approximately 200 cubic lightyears.

The Milky Way is 800 trillion cubic light years. Now it's quite clearly stated that the Imperium only occupies a merest fraction of the galaxy.

Lets say that the Imperium occupies 0.01% of the galaxy's volume(that's 100th of 1%). 800 trillion x .001 = 8,000,000,000 cubic lightyears. 8 billion cubic lightyears.

This would mean the Imperium has ~40,000,000 sectors.

40 million sectors. Each with 50-75 ships on average.

Low end estimates with each sector averaging 50 ships:

Battleships: 10 per sector. 400 million Battleships

Cruisers: 15 per sector. 600 million Cruisers

Escorts: ~1 billion Escort vessels.



Yes, these numbers seem large. But when you're talking a empire that is realistically defending several hundred million planets it's all put in perspective. You might occupy 1 million worlds, but you'd have picket lines beyond that so your navy is realistically covering dozens of totally unoccupied worlds for every one that actually has Imperial citizens.

[img]

 John Prins wrote:
WH40K has zero sense of scale. It's got hive worlds with populations in the trillions, but 3000 ships per sector? Literally over a million worlds controlled by humanity, but less than 15000 ships in the navy? The Imperial Navy should number in the millions of ships, especially given how unreliable warp travel is - which is to say you can't count on a large percentage of the ships to be available at any one time, because warp travel takes however long the warp feels like.

Never mind that the Navy has to transport the Army, which is basically uncountable.

Firstly, as noted, the numbers in discussion are cruisers only - not escorts like destroyers, frigates, or system defence monitors, or other weighrs of capital ship like battleships or grand cruisers. Secondly, the estimate is massively low.

Thirdly, it's not including the chartist fleet (mrchant ships and indentured transports, who hump guardsmen around.


As noted, descriptions of a sector battlefleet (battlefleet gothic, dark heresy, armageddon &blavk crusade background, shield of baal background) generally put the size at a couple of dozen capital ships to less than 100 capital ships, which is about the same as the usual size of a sector (gothic sector is about thirty worlds, calixis just over a hundred).

In other words, whilst naval strength may vary wildly in any specif sector depending on wars and importance, a good estimate is 1 cruiser or battleship class vessel for every major world of the imperium, plus a short handful of frigates, destroyers and non-warp capable local system defence fleet ships. The merchant fleet of a sector is hard to estimate but vast, because it has to manage tasks like shipping in enough food and water to sustain hive worlds...

I fear you estimate for the imperiums's total size is a couple of orders of magnitude high, as a phrase used to describe it in several RPG sourcebooks, rulebooks and novels is an 'empire of a million worlds' - that would mean somwhere between 10,000 and 100,000 sectors. Using your estimates that's still between half a million and 5 million navy ships (interestingly,roughly the same number of navy warships as there are space marines...)

locarno24 wrote:
[img]

 John Prins wrote:
WH40K has zero sense of scale. It's got hive worlds with populations in the trillions, but 3000 ships per sector? Literally over a million worlds controlled by humanity, but less than 15000 ships in the navy? The Imperial Navy should number in the millions of ships, especially given how unreliable warp travel is - which is to say you can't count on a large percentage of the ships to be available at any one time, because warp travel takes however long the warp feels like.

Never mind that the Navy has to transport the Army, which is basically uncountable.

Firstly, as noted, the numbers in discussion are cruisers only - not escorts like destroyers, frigates, or system defence monitors, or other weighrs of capital ship like battleships or grand cruisers. Secondly, the estimate is massively low.

Thirdly, it's not including the chartist fleet (mrchant ships and indentured transports, who hump guardsmen around.


As noted, descriptions of a sector battlefleet (battlefleet gothic, dark heresy, armageddon &blavk crusade background, shield of baal background) generally put the size at a couple of dozen capital ships to less than 100 capital ships, which is about the same as the usual size of a sector (gothic sector is about thirty worlds, calixis just over a hundred).

Your post has several errors. The 50-75 warships per sector does include escorts like destroyers and frigates. Read the quote from the BFG rulebook, earlier in this very same thread. It includes those but excludes spaceships that cannot travel in the warp such as system monitors.

Also the Gothic Sector by counting the systems in the back of the BFG rulebook alone is 81 systems, and that is an underestimate since more systems are named in the BFG novels from BL. Seriously both of these errors could be rectified just by looking at the rulebook or counting the systems on the map! This is how errors and misconceptions get perpetuated, by misremembered information repeated without actually checking the sources.


The fundamental point about the Imperial Navy is that it is spread thin. Many ships are on patrols and showing the flag to isolated worlds. Most of the fighting they do will be against pirate bands (not Chaos aligned raiders), which would be hard pressed to field any ship larger than an escort. The fighting in BFG between capital ships is already atypical.

Finally like the Imperial Guard, the Imperial Navy relies on reinforcements from elsewhere if the sector is seriously invaded. The sector fleet's job is to hold the line long enough for other sectors to send aid. That is precisely what happened in the Gothic War. That is why initially the Imperial Navy always seems to get overwhelmed. It is spread thin while any invader can focus forces. However over time the weight of additional reinforcements will swing things back in the Imperial Navy's favor.

Earlier in the thread, there also seemed to be a misconception about the danger of warp travel. Sure there is a danger, but it is overstated and overhyped. Why? Because the Imperium has so many worlds that are utterly dependent on interstellar trade and supplies to survive, and yet they have survived for hundreds or thousands of years. For hive worlds dependent on regular vast imports of food or forge worlds dependent on raw material imports, they have to be able to expect the imports to arrive within a reasonable timeframe. Clearly warp travel has to be reasonably reliable else they would have perished long ago.

 Warpig1815 wrote:


Fair enough. However, here's where I start to get a little disbelieving:

A Space Marine Strike Cruiser is equipped to hold one full SM company. A Battle Barge can hold up to 3 companies. So assuming these numbers to be correct, a full SM Legion of circa 100,000 Marines would require either 333 Battle Barges or 1000 Strike Cruisers, or more likely a combination of the two, to carry the Legion to battle. So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH (Even if split up into warbands or replaced with similar vessels), then the Traitor Legions alone can muster up to 9000 Cruiser class vessels.

That's got to be wrong, so what would be a more reasonable estimate of the Imperium's naval strength?

That is where you are wrong. A strike cruiser is more than large enough for an entire chapter of space marines. There are chapters that only have 1 and a few escorts and yet have no problem moving the entire chapter about.

A battle barge is massively larger. No single chapter can fully utilize their massive capabilities. The fluff about the battle barges from before the Heresy that survive usually describe them as having massive decks for troops and launch operations that sit unused collecting dust.

It seems therefore, that the Traitor Legions alone can muster three times as many Cruisers as the whole Imperium, without even taking into account the many billions of traitors and renegades in the Lost and the Damned and the thousands more vessels they can muster.

The traitor fleet is smaller but similar in size to the imperial fleet. I believe it is a similar composition of escorts, cruisers, battleships and superbattleships. There might be slightly less escorts per capital ship. Just a feeling.

A strike cruiser has always been described as carrying a single battle company.

This is true from epic armageddon, battlefleet gothic armada, and numerous black library novels.

Preheresy venerable battle barges will be sized for huge forces, but 'modern' barges are indeed for three companies.

Note that thats not the same as the ship being for 100 or 300 people: even a strike cruiser - a lighg cruiser byy most standards - has tens of thousands of crew - but its troop capacity over and above said crew is 100 astartes (plus tanks, plus gunships, plus attached reserve company, scout company and veteran company units, plus armour and apothecaries). If you just wanted to transport "rough field barracks" fashion, the you could eadily pack in a chapter, but at a cost of next to no military potential when you arrived.

I don't think Ive ever heard of a chapter with only a sibgle strike cruiser (barring 'decimated survivors')

 Exergy wrote:

 Warpig1815 wrote:


Fair enough. However, here's where I start to get a little disbelieving:

A Space Marine Strike Cruiser is equipped to hold one full SM company. A Battle Barge can hold up to 3 companies. So assuming these numbers to be correct, a full SM Legion of circa 100,000 Marines would require either 333 Battle Barges or 1000 Strike Cruisers, or more likely a combination of the two, to carry the Legion to battle. So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH (Even if split up into warbands or replaced with similar vessels), then the Traitor Legions alone can muster up to 9000 Cruiser class vessels.

That's got to be wrong, so what would be a more reasonable estimate of the Imperium's naval strength?

That is where you are wrong. A strike cruiser is more than large enough for an entire chapter of space marines. There are chapters that only have 1 and a few escorts and yet have no problem moving the entire chapter about.

A battle barge is massively larger. No single chapter can fully utilize their massive capabilities. The fluff about the battle barges from before the Heresy that survive usually describe them as having massive decks for troops and launch operations that sit unused collecting dust.

It seems therefore, that the Traitor Legions alone can muster three times as many Cruisers as the whole Imperium, without even taking into account the many billions of traitors and renegades in the Lost and the Damned and the thousands more vessels they can muster.

The traitor fleet is smaller but similar in size to the imperial fleet. I believe it is a similar composition of escorts, cruisers, battleships and superbattleships. There might be slightly less escorts per capital ship. Just a feeling.

Ok yeah. Modern might be designed for 300, maybe with excess for support marine crews and such so maybe 350-400 max.

Old ones. They probbly could carry a entire chapter. Maybe not deploy one but carry a chapter if you reactivated all there old decks and brought all there barracks decks to use.

Also they all vary alot as no set design.
There vary from custom build to modifed Batltlewagon hulls, or suitablely armoured and reinforced classes they can upgrade into them.
There Is no kinda generic class.

They are each unique.

Yeah. The ships marines currently use were originally designed to deploy many more marines than typically are.

Battlebarges could hold and deploy most of a chapter if necessary. But it's pretty rare to use all that space. Chapters are typically spread out and the ships are rarely at capacity.

A relatively new chapter with only a few ships might have more crowded conditions, but thats not the norm.

 Grey Templar wrote:
The numbers of the Imperial navy are not hard and fast. But we can make some educated guesses going by the official numbers.

http://wh40k.lexicanum.com/wiki/Battlefleet

A Battlefleet is the basic unit of the Imperial navy. Consisting of between 50-75 ships on average. Lets say 20% of the ships are battleships, 30% are Cruisers, and 50% are escort vessels.

Every Sector has it's own Battlefleet.

http://wh40k.lexicanum.com/wiki/Sector

A sector is a unit of volume, approximately 200 cubic lightyears.

The Milky Way is 800 trillion cubic light years. Now it's quite clearly stated that the Imperium only occupies a merest fraction of the galaxy.

Lets say that the Imperium occupies 0.01% of the galaxy's volume(that's 100th of 1%). 800 trillion x .001 = 8,000,000,000 cubic lightyears. 8 billion cubic lightyears.

This would mean the Imperium has ~40,000,000 sectors.

40 million sectors. Each with 50-75 ships on average.

Low end estimates with each sector averaging 50 ships:

Battleships: 10 per sector. 400 million Battleships

Cruisers: 15 per sector. 600 million Cruisers

Escorts: ~1 billion Escort vessels.



Yes, these numbers seem large. But when you're talking a empire that is realistically defending several hundred million planets it's all put in perspective. You might occupy 1 million worlds, but you'd have picket lines beyond that so your navy is realistically covering dozens of totally unoccupied worlds for every one that actually has Imperial citizens.

This is the only number so far that makes the merest hint of sense on a galactic scale.

 Grey Templar wrote:
Numbers!

Not quite. A sector is a cube 200 light years per side, not a cube of 200 cubic light years volume. So divide your numbers by (appropriately) 40,000 and we're about right. Which is still a heck of a lot of ships - 10 million battleships, 15 million cruisers etc.

 Grey Templar wrote:


A Battlefleet is the basic unit of the Imperial navy. Consisting of between 50-75 ships on average. Lets say 20% of the ships are battleships, 30% are Cruisers, and 50% are escort vessels.

Far too many Battleships given that number of cruisers. Cruisers outnumber battleships 4 or 5:1. The original rules for BFG required you to have 3 cruisers per battleship as a limit.

Also do remember a frigate is a considerable warship

 Graphite wrote:

 Grey Templar wrote:
Numbers!

Not quite. A sector is a cube 200 light years per side, not a cube of 200 cubic light years volume. So divide your numbers by (appropriately) 40,000 and we're about right. Which is still a heck of a lot of ships - 10 million battleships, 15 million cruisers etc.

Ummm. No.

A cube which is 200x200x200 lightyears is 200 cubic lightyears.

Just like a Cubic meter is a "box" where each side is 1 meter across. So a cube that is 200 light years per side is, by very definition, 200 cubic lightyears.

Iron_Captain wrote:

 Warpig1815 wrote:
I've been playing Battlefleet Gothic: Armada recently and in the course of reading up on the Imperial Navy, I couldn't really find any firm numbers of the size of Imperial Fleets. Indeed the one fact I did come across was that in the Segmentum Obscurus alone (1 out of the 5) there were only 600 Lunar Class Cruisers, which were meant to be the most numerous of Cruiser designs. So, onto a little maths, bearing in mind that this is all extrapolation on my part:

If the Segmentum Obscurus has 600 Cruisers, then being roughly the same size as Solar and Pacificus combined, the same size as Tempestus and half the size of Ultima that would nominally put total Imperial Cruisers at around 3000 Cruisers.

Fair enough. However, here's where I start to get a little disbelieving:

A Space Marine Strike Cruiser is equipped to hold one full SM company. A Battle Barge can hold up to 3 companies. So assuming these numbers to be correct, a full SM Legion of circa 100,000 Marines would require either 333 Battle Barges or 1000 Strike Cruisers, or more likely a combination of the two, to carry the Legion to battle. So, assuming all 9 Traitor Legions still possess roughly the same fleet assets as they did after the HH (Even if split up into warbands or replaced with similar vessels), then the Traitor Legions alone can muster up to 9000 Cruiser class vessels.

It seems therefore, that the Traitor Legions alone can muster three times as many Cruisers as the whole Imperium, without even taking into account the many billions of traitors and renegades in the Lost and the Damned and the thousands more vessels they can muster.

That's got to be wrong, so what would be a more reasonable estimate of the Imperium's naval strength?

That seems indeed wrong. Firstly because the Legions were not just limited to strike cruisers and battle barges (they had much larger ships). Also, even in 40k, battle barges can be of wildly varying size. 'Battle barge' is not the name of a standardised ship class or such, it is simply a designation for any large warship owned by a Space Marine chapter. Entire Chapters are based out of a single battle barge, indicating some can carry far more than 3 companies.
Secondly, the estimate is wrong because after the Heresy and the Scouring, no SM Legion had numbers even close to 100,000.
Thirdly, it seems wrong because in the more than 10,000 years of war that seperate the end of the Scouring and 'present-day' 40k, the vast majority of traitor legion assets will have been destroyed in the endless campaigns against the Imperium, with only few opportunities for replacement.
And last but not least, there are as many cruisers as the plot demands. The amount of cruiser classes that exist is unknown. If they run out of Lunar-Class cruisers, the writers will just invent a new class.

Just to say - It's not me that is 'wrong', because I don't make the numbers up. The numbers come from Lexicanum, and each fact is fully sourced to one of Games Workshop's sources. In this case, the Strike Cruiser quote comes straight from the 2004 Book Battlefleet Gothic: Armada, page 23. The Battle Barge number comes from Imperial Armour Volume Two: Space Marines and Forces of the Inquisition, pg. 10. Whether GW is right or wrong with these numbers is a different matter (the matter we are discussing) but the numbers are still given as canon values in several sources.

Obviously 9000 is not a hard number for the Traitor Legions combined fleet. It may be way higher if said Legions utilise large numbers of escort vessels. It may be far lower if the Legions travel mainly on board one giant Gloriana Battleship or fewer Battle Barges. It's more likely to be somewhere between the two. 9000 is just a ballpark figure if all the Traitor Legions travelled on board Cruiser Class Vessels capable of supporting the number of Astartes that the sources provide.

Grey Templar wrote:The numbers of the Imperial navy are not hard and fast. But we can make some educated guesses going by the official numbers.

http://wh40k.lexicanum.com/wiki/Battlefleet

A Battlefleet is the basic unit of the Imperial navy. Consisting of between 50-75 ships on average. Lets say 20% of the ships are battleships, 30% are Cruisers, and 50% are escort vessels.

Every Sector has it's own Battlefleet.

http://wh40k.lexicanum.com/wiki/Sector

A sector is a unit of volume, approximately 200 cubic lightyears.

The Milky Way is 800 trillion cubic light years. Now it's quite clearly stated that the Imperium only occupies a merest fraction of the galaxy.

Lets say that the Imperium occupies 0.01% of the galaxy's volume(that's 100th of 1%). 800 trillion x .001 = 8,000,000,000 cubic lightyears. 8 billion cubic lightyears.

This would mean the Imperium has ~40,000,000 sectors.

40 million sectors. Each with 50-75 ships on average.

Low end estimates with each sector averaging 50 ships:

Battleships: 10 per sector. 400 million Battleships

Cruisers: 15 per sector. 600 million Cruisers

Escorts: ~1 billion Escort vessels.



Yes, these numbers seem large. But when you're talking a empire that is realistically defending several hundred million planets it's all put in perspective. You might occupy 1 million worlds, but you'd have picket lines beyond that so your navy is realistically covering dozens of totally unoccupied worlds for every one that actually has Imperial citizens.

That's maybe a high estimate IMHO. The IoM has around 1 Million worlds, but those worlds can range in population from 3.4 Million of Fenris to the 500 Billion of Ichar IV (Depending on the Authors taste or course). If we were to average the population of an Imperial World at a conservative 21 Billion (Triple of today's numbers) we would get the following:

1 Million x 21 Billion = 2.1 Quadrillion (21,000 Billion by the US System) - However if, by your numbers, there are circa 2 Billion Imperial Navy Vessels, then each ship could only have a crew of 10,500. However, we know that some vessels have a crew of 100,000 - the Overlord Class Battlecruiser for instance. So for your numbers to work, either every world would have to have trillions of inhabitants in order to supply not only the Fleet, but also the Guard and the wider Imperium's infrastructure (Which isn't infeasible by the settings standards, but there are no known instances of it occurring), or the Imperium would have to have far more than 1 million worlds under it's control.

Of course, they're all lines of thought we are never going to be able to reconcile with GW's facts.

You're failing to account for population growth and being way low in what population estimates are. I did a very very conservative estimate on the Imperium's population growth. The yearly population growth was in the low quadrillions with a population growth of less than 1/2 of 1%. Plus the Imperium's populations aren't just on planets. There is a significant portion of their population that live their entire lives aboard ships and space stations. Many ships would have their crew be largely hereditary. It's enough to where one of the race options for the RPG is Voidborn.


If we just talk about hive worlds. There are approximately 32,380 hive worlds in the Imperium. http://wh40k.lexicanum.com/wiki/Hive_World

A single Hive can have many billions of people in it.

If we go with your number of 21 billion people per hive world(which is ludicrously low I might add. 50-60 billion would be more reasonable as an average), at 32,380 hive worlds, we get a population of ~679,980,000,000,000

Times a population growth of .001(One tenth of 1%), we get an available work force of 679,980,000,000

That's a replacement force of 670 billion people, from Hive worlds alone. This totally ignores any population growth from Civilized Worlds(which can still have a population of up to 10 billion, and overall would likely rival Hive worlds for total population.http://wh40k.lexicanum.com/wiki/Civilised_World), space stations(which can be as large or larger than hives), the existing crew of ships, or any other type of planet where the Imperium gets recruits.

That's also with a silly tiny population growth.

If we go with a growth rate of 1%(still much lower than modern day) with your 21 billion number, we get 6,799,800,000,000. 6.7 trillion replacements from hive worlds alone.

Just my tuppence worth, but if The Night Lords Novels are anything to go by, then while the numbers of ships available to the traitor legions may not be that high.

I don't have the books to hand, but if I remember correctly most of the remaining ships mustered to attack the assassin's world and it was in the hundreds?

In contrast there's a decent chance that the Alpha Legion might have most of its fleet left.

Thanks