Stacking limits

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This is a summary of information on stacking limits and frontage. Detailed Information about stacking limits and frontage is provided in several other pages, and you can find links to them all here.


N.B. For a full description of stacking limits for land units, see: Land combat reference


Stacking penalties depend on the number of Divisions (not Brigades) involved in the battle, and on the number of directions of attack (attack vectors). Converging attacks... e.g.: attacking from several provinces into one enemy province, or defending a province against an attack from enemies in several provinces... allow a higher stacking limit and give a lower stacking penalty.

allowed units in a combat = integer ( frontage / unit width ) + 1

Armour brigades start out with a combat width of 2, which can later be researched to become 1. All other combat brigades have a combat width of 1 (Militia and Partisans can have a tech researched that drops their width to .5) and support brigades have a combat width of 0. A typical infantry division will have a combat width of 3 (3XINF +1 ART ). An early war Panzer division might have 2XARM + 1 MOT + 1 ENG which would give it a combat width of 5 . A Light armoured division (1X LARM+2X MOT + 1 ENG) would have a combat width of 3. This is summarised in the table below:

Type Panzer Division Light Division Motorised Division Infantry Division
Brigades 2 ARM, 1 SS, 1 ENG 1 ARM, 2 MOT, 1 ENG 3 MOT, 1 AC 3 INF, 1 ART
Frontage 4+1+0 = 5 2+2+0 = 4 3 X 1 + 0 =3 3 X 1 + 0 = 3

So, the usual maximum is four three-wide divisions attacking a single province from a single province, six divisions from two provinces, and seven from three provinces.


For more information on Frontage, see: Land combat reference and combat width

I province has 10 frontage. Each province added after the first will add 5 Frontage to the fight. In other words, attacking from 2 provinces gives you a total Frontage of 15. 3 provinces means Frontage 20. 4 provinces means Frontage 25. Frontage can be exceeded without penalty by one division, so typically a frontage of 15 is allowed on a single province with 3 divisions X 5 bde (10+5) or a frontage of 12 with 4 divisions X3 bde (9+3). It doesn't matter how long the border is between provinces, an additional border always adds the same amount of frontage.

In the following table, the armoured divisions have a combat width of 5 and the Infantry divisions have a combat width of 3. D=one division equivalent e.g. 3 bdes for a 3 bde division.

No. of Provinces 1 1 2 2 3 3 4 4
Frontage (bdes) 10+D 10+D 15+D 15+D 20+D 20+D 25+D 25+D
Stacking (Divs) 5 3 6 4 8 5 9 6

frontage = 5 x ( #_of_attack_vectors + 1 ) e.g.: an attack from four provinces has a frontage of 5x(4+1)=25.

allowed units in a combat = integer ( frontage / unit width ) + 1

e.g.: a frontage of 25 (a four-province attack) with 3-width Divisions such as INFx3/ARTx1 allows room for integer(25/3)+1=9 Divisions to participate.

stacking limit = ( 3 x number_of_attack_vectors ) + 1

e.g.: attacking from four provinces into one allows (3x4)+1=13 Divisions in the attacking stack, without any stacking penalty. Note that four of them will be "in reserve", since there is only room (on a frontage of 25) for nine of them to attack at once... again, assuming that they are width-3.

stacking penalty = -100% x ( 1 - ( 0.9 to_the_power_of ( #_of_attacking_units - stacking_limit ))) + theatre_commander's_skill

e.g.: attacking with six 2-width units (such as INFx2/ARTx2) in a single-province attack (frontage=5x(1+1)=10) gives you a stacking limit of four Divisions ((3x1)+1=4), hence an over-stack of two Divisions and a stacking penalty of -19% less the theatre commander's skill... a skill-3 theatre commander would reduce the penalty from -19% to -16%.


In Summary…..

  • Frontage (brigades): 10 +1 division equivalent for one province, + 5 for each additional province.
  • Stacking limit (divisions): 4 ( for 1 province), 6 (for 2 provinces), 7 (for 3 provinces), 9 (for 4 provinces) for regular infantry


For more information on stacking limits to air forces, see: Air combat reference and Airforce

The leader benefits vanish when you do not have an appropriate leader for your stack size, which is 4/8/12/16 for air units Since the air stacking penalty is huge (10% for every aircraft after the first), you will actually never want a stack of more than four planes and thus never have to promote an air leader beyond the basic rank.

The stacking penalty used for aircraft creates a normal distribution penalty whereby the maximum effectiveness of aircraft stacks is five or six (five for bombers).

  • TFH update: Stacking penalties cannot reduce efficiency below 20%. The cap limits them to an 80% stacking penalty, which leaves 20% efficiency. If you throw enough planes at the problem (like 20), you can actually overcome the stacking penalty and do respectable damage. There is no longer a 0% efficiency situation with 10 or more planes.


For more information on stacking limits for Naval Units, see: Naval strategy

The command stack size is 6/12/18/30 for naval units. A fleet has a 4% penalty to Positioning per combined Hull above 16 (TFH). This penalty not only makes it harder for a fleet to hit the enemy, but also increases the chances of friendly fire. The hull values of all the ships in the squadron are added together. If the total is bigger than 16, you get positioning penalties in combat (they get in each other’s way). This penalty is 4% per point over 16 hull. So in theory, a total hull value of 16 or less would be ideal. However, these penalties are capped at 80%, so combining good doctrines with an excellent admiral means you can effectively ignore fleet size if opposed by an inferior admiral. The stacking penalty can be reduced by the theatre commander's skill.