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Damage Calculations

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Map Mechanics and Nodes  · Evacuation  · Damage Calculations  · Accuracy, Evasion and Criticals

This page lists all the applicable damage formulas for a single fleet. Special cases like Combined Fleets and Land-Based Air Squadrons have their own adjustments to the standard damage formulas. Please see those pages for further details.

Please note that all formulas between [math]\displaystyle{ \lfloor \ \rfloor }[/math] or marked with [math]\displaystyle{ \downarrow }[/math] are rounded down.

  • For example, [math]\displaystyle{ \lfloor 4.2 \rfloor = 4 }[/math].
  • [math]\displaystyle{ 4.2 \times_\downarrow 1.5 = \lfloor 4.2 \times 1.5 \rfloor = \lfloor 6.3 \rfloor = 6 }[/math], but [math]\displaystyle{ 4.2 \times_\downarrow 1 = 4.2 }[/math] (by definition, [math]\displaystyle{ \times_\downarrow }[/math] is then a non-commutative non-associative operator, it is assumed to be left-associative with lower priority than the usual multiplication operator).

Damage Formula

[math]\displaystyle{ \text{Damage} = \biggl \lfloor \biggl ( \lfloor \text{Atk}_\text{cap} \rfloor \times \text{Mod}_\text{spotting} \times_\downarrow \text{Mod}_\text{AP} \times \text{Mod}_\text{CVCI} \times_\downarrow \text{Crit} \times \text{Mod}_\text{post} - \text{DEF} \biggr ) \times \text{Ammo} \biggr \rfloor }[/math]


  • [math]\displaystyle{ \text{Atk}_\text{cap} }[/math] the Cap Adjusted Attack Power,
  • [math]\displaystyle{ \text{Mod}_\text{spotting} }[/math] the bonus from artillery spotting,
  • [math]\displaystyle{ \text{Mod}_\text{CVCI} }[/math] the bonus from carrier cut-ins,
  • [math]\displaystyle{ \text{Mod}_\text{AP} }[/math] the bonus from an AP shells,
  • [math]\displaystyle{ \text{Mod}_\text{post} }[/math] any remaining post-cap modifiers that are applicable,
  • [math]\displaystyle{ \text{Crit} }[/math] the critical strike modifier,
  • [math]\displaystyle{ \text{Ammo} }[/math] the remaining ammunition modifier,
  • [math]\displaystyle{ \text{DEF} }[/math] the defensive power of the target.

Where, Cap Adjusted Attack Power is Basic Attack Power that has been adjusted by applying the damage cap. This only applies if the calculated pre-cap attack power is above the damage cap.

[math]\displaystyle{ \text{Atk}_\text{cap} = \text{Cap} + \sqrt{\left ( \text{Atk}_\text{base} \times \text{Mod}_\text{pre}\right)-\text{Cap}} }[/math]

  • [math]\displaystyle{ \text{Cap} }[/math] is the damage cap relevant to the phase.
  • [math]\displaystyle{ \text{Atk}_\text{base} }[/math] is the basic attack power of the relevant attack.
  • [math]\displaystyle{ \text{Mod}_\text{pre} }[/math] is any pre-cap modifiers that are applicable.

Defense Power

[math]\displaystyle{ \text{DEF} = \left( \text{Armor} \times 0.7 + \text{Armor}_\text{rand} \times 0.6 \right) - \text{Pen} }[/math]

  • [math]\displaystyle{ \text{Armor} }[/math] is the armor of the target including all equipment and upgrade bonuses.
  • [math]\displaystyle{ \text{Armor}_\text{rand} }[/math] is a random number between [math]\displaystyle{ 0 }[/math] and [math]\displaystyle{ \lfloor\text{Armor}\rfloor - 1 }[/math]
    • Note that it is inclusive, meaning it can also output [math]\displaystyle{ 0 }[/math] and [math]\displaystyle{ \lfloor\text{Armor}\rfloor - 1 }[/math]
  • [math]\displaystyle{ \text{Pen} }[/math] is any applicable armor penetration mechanic:
    • See ASW for details on ASW armor penetration,
    • Some debuffs may include armor penetration.

Therefore, the maximum armor value [math]\displaystyle{ \text{Armor} \times 1.3 - 0.6 }[/math] and the minimum armor value is [math]\displaystyle{ \text{Armor} \times 0.7 }[/math]. This makes the maximum defensive power a target can have is 1.3x armor and the lowest is 0.7x armor.


  • The range of armor values is uniformly distributed, every armor roll has the same chance of occurring.

Basic Attack Power Formulas

The following formulas only apply to single fleets. Please see Combined Fleet, Land-Based Air Squadron and Support Expeditions for more details.


  • [math]\displaystyle{ \text{FP} }[/math] is the firepower Firepower of the ship including equipment.
  • [math]\displaystyle{ \text{TP} }[/math] is the torpedo Torpedo Attack of the ship including equipment or the torpedo of a plane.
  • [math]\displaystyle{ \text{ASW} }[/math] is the anti-submarine Anti-Submarine Warfare of the ship or equipment.
  • [math]\displaystyle{ \text{DB} }[/math] is the dive bombing Dive Bomber Attack of the plane.
  • [math]\displaystyle{ \bigstar }[/math] is the upgrade bonus of the equipment.
  • [math]\displaystyle{ \text{Plane}_\text{Count} }[/math] is the remaining amount of planes in a slot, performing the attack.


This applies to Jet Assaults, Airstrikes, and LBAS.

[math]\displaystyle{ \text{Airstrike Power} = \text{Type} \times \biggl( \left( \text{DB or TP} + \bigstar \right) \times \sqrt{\text{Plane}_\text{Count}} + 25 \biggr) }[/math]

  • [math]\displaystyle{ \text{Type} }[/math] is a multiplier based on the type of the plane. See below for details.
Type Multiplier Notes
Torpedo Bomber Torpedo Bombers 0.8x or 1.5x The multiplier is chosen randomly.
The chance is roughly 50%.
Dive Bomber
Seaplane BomberBomber
Dive Bombers
Seaplane Bombers
(During jet assault)
(During normal bombing)
  • Airstrike power is calculated independently for each equipment slot on the carrier.
  • The firepower of the carrier does not affect airstrike power.
  • Torpedo Stat from fit does not contribute to airstrike damage
  • The power is calculated after the air combat and anti-air fire phases which means bombers getting shot down will affect the final calculation.
  • It is not affected by engagement, formation or damage states.
  • It is affected by contact.
  • For LBAS, the stat used when calculating attack power varies based on the target. Please see LBAS for more details.

Surface Shelling

[math]\displaystyle{ \text{Shelling Power} = \text{FP} + \bigstar + 5 }[/math]


  • The caliber of the gun does not affect damage.
  • Abyssal installations that are not equipped with a plane that has a torpedo or dive bombing stat will use the surface shelling formula for calculating damage.

Carrier Attacks

[math]\displaystyle{ \text{Power}_\text{carrier} = \bigl\lfloor \left( \text{FP} + \left(\text{TP} + \bigstar \right) + \lfloor \text{DB} \times 1.3 \rfloor + \bigstar \right) \times 1.5 \bigr\rfloor + 55 }[/math]


  • Dive and Torpedo groups contribute, respectively, 1.95 and 1.5 times their dive bomb and torpedo stats towards shelling power
  • Torpedo Stat from fit does not contribute to shelling damage
  • If a carrier is not equipped with any torpedo or dive bombers, she will not participate in shelling.
    • This also applies if they have lost all bombers during the aerial combat phase.
    • But even if an air group has had all its planes shot down, it will still contribute towards carrier shelling power (if the CV is still capable of attacking).
  • Remember that there are potentially two sources of [math]\displaystyle{ \bigstar }[/math] bonuses.
    • Torpedo bomber upgrades to the torpedo stat.
    • Secondary and machine gun upgrades to the firepower stat.
  • Slot sizes and the number of remaining aircraft do not affect carrier attack power during shelling.
  • Carriers have the easiest time hitting the damage cap. This makes them very powerful assets for the fleet.
  • Abyssal installations equipped with a plane that has a torpedo or dive bombing stat will use the carrier formula for determining shelling damage.
  • Planes are not shot down when a carrier participates in shelling

Torpedo Attacks

[math]\displaystyle{ \text{Torpedo Power} = \text{TP} + \bigstar + 5 }[/math]

Torpedo Attacks only include the Opening Torpedo Salvo and Closing Torpedo Salvo.

  • Submarines and Abyssal installations cannot be targeted by torpedoes.
    • If the only available targets are submarines or installations, the attack will trigger but always miss.
  • A ship must have a base torpedo stat of more than 0 to perform torpedo attacks.

Anti-Submarine Warfare

The stats used to calculate damage against submarines is the Anti-Submarine Warfare ASW.

  • When contributing to ASW power, Base Anti-Submarine Warfare ASW is square rooted, while equipment ASW is multiplied by 1.5.
    • Anti-submarine weaponry is therefore the primary source of ASW damage, with the base ship ASW playing a very minor role damage-wise.
    • However, base ship ASW is the primary determinant of whether a ship can reach 100 total ASW to perform "Opening ASW" (OASW) attacks.
  • Unlike sheeling, ASW damage is capped at 170.

ASW attacks have different modifiers gained from Formations,

  • [math]\displaystyle{ \text{ASW Power} = \left( 2\sqrt{\text{ASW}_\text{ship}} + 1.5\text{ASW}_\text{equip} + \bigstar + \text{Type}_\text{ship} \right) \times \text{Mod}_\text{synergy} }[/math]


  • [math]\displaystyle{ \text{Type}_\text{ship} }[/math] a constant depending on the type of the ship performing the attack. See below for details.
Ship Type Constant
Ship Types [math]\displaystyle{ \text{Type}_\text{ship} }[/math]
Coastal Defence Ships (DE)
Destroyers (DD)
Light Cruisers (CL/CT)
Oilers (AO) (without carrier bomber)
Aviation Cruisers (CAV)
Aviation Battleships (BBV)
Seaplane Tenders (AV)
Light Carriers (CVL)
Landing Ships (LHA)
Oilers (AO) (with carrier bomber)
  • [math]\displaystyle{ \text{Mod}_\text{synergy} }[/math] the synergy multiplier bonus from using certain combinations of ASW equips (see below).
  • The bonuses do not stack, meaning only the highest possible bonus applies.
    • The exception is the depth charge penetration detailed above.
  • Multiple equipments of the same type still only apply the bonus once.
  • There is an accuracy bonus as well but it is small. Stacking sonars will give a bigger accuracy bonus.
ASW Damage Synergy
Small SONARSmall Small Sonars
Equipment Card Type 93 Passive Sonar.png
Type 93 Passive Sonar
Equipment Card Type 4 Passive Sonar.png
Type 4 Passive Sonar
Equipment Card Type 3 Active Sonar.png
Type 3 Active Sonar
Equipment Card Type 3 Active Sonar Kai.png
Type 3 Active Sonar Kai
Equipment Card Type124 ASDIC.png
Type124 ASDIC
Equipment Card Type144 147 ASDIC.png
Type144/147 ASDIC
Equipment Card HF DF + Type144 147 ASDIC.png
HF/DF + Type144/147 ASDIC
Large SONARLarge Large Sonars
Equipment Card Type 0 Passive Sonar.png
Type 0 Passive Sonar
Depth Charge ProjectorDCP Depth Charge Projectors (DCP)
Equipment Card Type 94 Depth Charge Projector.png
Type 94 Depth Charge Projector
Equipment Card Type 3 Depth Charge Projector.png
Type 3 Depth Charge Projector
Equipment Card Type 3 Depth Charge Projector (Concentrated Deployment).png
Type 3 Depth Charge Projector (Concentrated Deployment)
Equipment Card Prototype 15cm 9-tube ASW Rocket Launcher.png
Prototype 15cm 9-tube ASW Rocket Launcher
Equipment Card RUR-4A Weapon Alpha Kai.png
RUR-4A Weapon Alpha Kai
Equipment Card Mk.32 ASW Torpedo (Mk.2 Thrower).png
Mk.32 ASW Torpedo (Mk.2 Thrower)
Depth Charge RacksDCR Depth Charge (Racks) (DCR)
Equipment Card Type 95 Depth Charge.png
Type 95 Depth Charge
Equipment Card Type 2 Depth Charge.png
Type 2 Depth Charge
Equipment Card Lightweight ASW Torpedo (Initial Test Model).png
Lightweight ASW Torpedo (Initial Test Model)
Equipment Card Hedgehog (Initial Model).png
Hedgehog (Initial Model)
Equipment Card Type 2 Depth Charge Kai Ni.png
Type 2 Depth Charge Kai Ni
ASW MortarOther ASW Mortars
Equipment Card Type 2 12cm Mortar Kai.png
Type 2 12cm Mortar Kai
Equipment Card Type 2 12cm Mortar Kai (Concentrated Deployment).png
Type 2 12cm Mortar Kai (Concentrated Deployment)
ASW Damage Modifiers: [math]\displaystyle{ \text{Mod}_\text{synergy} = {Mod}_\text{1} \times {Mod}_\text{2} }[/math]
[math]\displaystyle{ {Mod}_\text{1} }[/math] SONAR + Depth Charges
(Any Sonar + Any Depth Charge)
[math]\displaystyle{ {Mod}_\text{2} }[/math] Depth Charge ProjectorDCP + Depth Charge RacksDCR and NO Small SONARSmall 1.1
Small SONARSmall + Depth Charge ProjectorDCP + Depth Charge RacksDCR 1.25
[math]\displaystyle{ \text{Mod}_\text{synergy} }[/math] Small SONARSmall + Depth Charge ProjectorDCP + Depth Charge RacksDCR 1.4375[math]\displaystyle{ 1.15 \times 1.25 }[/math]
Large SONARLarge + Depth Charge ProjectorDCP + Depth Charge RacksDCR 1.265[math]\displaystyle{ 1.15 \times 1.1 }[/math]
Armor Penetration
Indepentant of synergies, some equipment provides additional armor penetration to ASW attacks.

The flat armor penetration value is calculated as follows:

  • [math]\displaystyle{ \text{Pen} = \sum\limits_{\text{Equipment}} \Big( \sqrt{\text{ASW}_\text{Equipment} - 2} + \text{Mod}_\text{ship} \Big) }[/math]
  • With:
    • [math]\displaystyle{ \text{ASW}_\text{Equipment} }[/math] the base ASW Anti-Submarine Warfare stat of the applicable equipment,
    • [math]\displaystyle{ \text{Mod}_\text{ship} }[/math] being 1 for DE, 0 otherwise,
  • Armor penetration from equipment stacks,
  • The final armor of the targetted submarine cannot go below 1.

Surface Night Battle

[math]\displaystyle{ \text{Night Battle Power} = \text{FP} + \text{TP} + \bigstar + \text{Mod}_\text{contact} }[/math]


Carrier Night Air Attacks

[math]\displaystyle{ \text{Night Battle Power}_\text{carrier} = \text{FP}_\text{ship} + \sum_\text{All Night Planes} \text{FP}_\text{night plane} + \text{TP}_\text{night plane} + \text{DB}_\text{night plane} + \text{Night Plane Bonus} }[/math]


[math]\displaystyle{ \text{Night Plane Bonus} = \mathrm{A} \times \text{Plane}_\text{Count} + \mathrm{B} \times \left( \text{FP}_\text{night plane} + \text{TP}_\text{night plane} + \text{DB}_\text{night plane} + \text{ASW}_\text{night plane} \right) \times \sqrt{\text{Plane}_\text{Count}} + \sqrt{\bigstar} }[/math]

  • Carriers must be equipped with a NOAP or NOAP+ in addition to "Night Planes", in order to perform carrier night attacks.
  • If the carrier night attack is evaded, it deals scratch damage instead.
  • Unlike daytime carrier attacks, it is possible to attack even if no bombers are equipped.
    • Night fighters are still needed to trigger the attack.
  • Like daytime carrier attacks, carriers are unable to attack if moderately damaged or worse.
    • Armored carriers are only disabled at heavy damage.
    • Carriers that can use the night battle shelling formula will use that instead if moderately damaged.
  • The formula only takes into account the base stats of the carrier and night attack capable planes equipped.
    • The Improvement stats are not taken into account.
      • This means any other stats and upgrade bonuses from equipment like guns and non-night-capable planes are ignored.
    • This also means that any Visible Bonus from Planes is also ignored.
  • Certain carriers (see here) are capable of performing night attacks but they are not carrier night air attacks and are just normal shelling attacks. Please see Carrier Night Attacks for more details.

Anti-Installation Attacks

Installations differ from regular enemy warships, as they are immune to certain attack elements like the torpedo stat, but are extremely weak against specialized gears.

Attack Power Corrections

After calculating the basic attack power of the attack being made, it is then adjusted based on various factors. Attack power modifiers can be split into pre- and post-cap modifiers. Post-cap modifiers are more powerful to have because they aren't reduced by the cap.

Attack Power Cap

The attack power cap varies depending on the phase of combat it is in.

Attack Type Cap
LBAS 170
Support Expeditions
Opening Torpedo Salvo 180
Closing Torpedo Salvo
Day shelling 220
Night battle 360
  • Any excess attack power above this cap is square-rooted. See the damage formula for how it is applied.
  • It is still worth aiming to go above the attack power cap because some pre-cap modifiers can severely reduce the attack power.

Pre-cap Modifiers


See Engagement for more details.

Form Damage Modifier Chance Chance with SaiunSaiun
Saiun (Eastern Caroline Air Group)
Saiun (4th Recon Squad)
Parallel Engagement
同航戦 (Doukousen?)
100% 45% 45%
Head-on Engagement
反航戦 (Hankousen?)
80% 30% 40%
Crossing the T (Advantage)
T字戦有利 (T Ji-sen Yuuri?)
120% 15% 15%
Crossing the T (Disadvantage)
T字戦不利 (T Ji-sen Furi?)
60% 10% 0%
  • All engagement forms affect both sides equally, including crossing the T (Advantage or Disadvantage).
  • Night battle and aerial combat are not affected by engagement.
  • OASW and opening torpedoes are affected by engagement even though it is only displayed after those phases.
  • Equipping a Reconnaissance AircraftSaiunSaiun
    Saiun (Eastern Caroline Air Group)
    Saiun (4th Recon Squad)
    effectively makes what would have been Crossing the T (Disadvantage) become Head-on engagement.
  • It is useful in some situations to not take the Saiun in order to get Crossing the T (Disadvantage). This is because it can also hamper the enemy from damaging the fleet.


See Formation for more details.

Formation Attack Power Modifiers
Formation Shelling Torpedo ASW Night Battle
Line Ahead
単縦陣 (Tanjuu-jin?)
100% 100% 60% 100%
Double Line
複縦陣 (Fukujuu-jin?)
80% 80% 80% 100%
輪形陣 (Rinkei-jin?)
70% 70% 120% 100%
梯形陣 (Teikei-jin?)
75% 60% 110% 100%
Line Abreast
単横陣 (Tan'ou-jin?)
60% 60% 130% 100%
警戒陣 (Keikai-jin?)
50% 100% 100% 50%
100% 100% 60% 100%
  1. The direct translation of "Keikai" is "alert".

Damage State

Damage State Shelling Torpedo ASW
Lightly Damaged (小破) 100% 100% 100%
Moderately Damaged (中破) 70% 80% 70%
Heavily Damaged (大破) 40% 0% 40%
  • Damage state does not affect aerial combat.
    • It will affect carrier attacks in the shelling phase.

Night Battle Special Attacks

Night Cut-Ins will apply extra modifiers if triggered.

Hidden Fit Bonuses

Unlike the other pre-cap bonuses, this is just a minor additive firepower bonus added for some ships (mostly cruisers) when equipped with certain guns.

Post-cap Modifiers

Aerial Contact

For more details please see Aerial Combat.

During aerial combat, there is a chance for the ships to trigger Contact. When it is triggered, the is a bonus multiplier applied to airstrike damage depending on the accuracy of the plane that triggered contact.

Accuracy Accuracy Damage Modifier
0 112%
1 112%
2 117%
3+ 120%

Artillery Spotting

For more details, please see Artillery Spotting

Attack Type Prerequisites Post-cap
Hits Notes
Main Zuiun Cut-in
(Zuiun CI)
Large Caliber Main GunZuiun Model Seaplane BomberZuiun Model Seaplane Bomber 1.35 ? 1 Ise-class Kai NiIse Kai Ni
Hyuuga Kai Ni
Main Suisei Cut-in
(Suisei CI)
Large Caliber Main GunDive BomberDive Bomber 1.3 ? 1
Main AP Shell Cut-in
Large Caliber Main GunLarge Caliber Main GunSeaplaneArmor-Piercing Shell 1.5 1.2 1
Secondary AP Shell Cut-in
(Sec APCI)
Large Caliber Main GunSecondary GunSeaplaneArmor-Piercing Shell 1.3 1.3 1
Secondary Radar Cut-in
(Radar CI)
Large Caliber Main GunSecondary GunSeaplaneRADAR 1.2 1.5 1
Secondary Cut-in
(Sec CI)
Large Caliber Main GunSecondary GunSeaplane 1.1 1.3 1
Double Attack
Large Caliber Main GunLarge Caliber Main GunSeaplane 1.2 1.1 2

Carrier Cut-In Attacks

For more details, please see Carrier Cut-In Attacks.

Attack Type Prerequisites Post-cap
FighterDive BomberTorpedo Bomber 1.25 1.2~1.3? 1
Dive BomberDive BomberTorpedo Bomber 1.2 1.2~1.3? 1
Dive BomberTorpedo Bomber 1.15 1.2~1.3? 1

Armor-Piercing Modifier

During day combat, certain enemy ships take extra damage from Armor-Piercing Shell AP ShellsType 91 Armor Piercing Shell
Type 1 Armor Piercing Shell
Type 1 Armor Piercing Shell Kai

  • The bonus only applies against BB, FBB, BBV, CA, CAV, CV, and CVL.
    • This include Installations.
    • This means that this bonus does not apply against CL, CLT, DD, and AV.
Type Modifier
Large Caliber Main GunArmor-Piercing Shell 1.08
Large Caliber Main GunArmor-Piercing ShellRADAR 1.10
Large Caliber Main GunArmor-Piercing ShellSecondary Gun 1.15
Large Caliber Main GunArmor-Piercing ShellSecondary GunRADAR 1.15
  • It is unadvisable to run any of the other setups beyond the most basic Gun+AP, as the other setups will interfere with artillery spotting and give worse bonuses.

Anti-Installation Equipment Modifiers

See the Anti-Installation page.

Critical Strikes

For more details on how critical chance is calculated, please see Accuracy, Evasion and Criticals.

Normal Criticals

Attack Type Modifier
Normal 100%
Critical 150%

Plane Proficiency Critical Modifier

Carriers get a bonus critical modifier when equipped with high proficiency planes. This modifier is multiplicative with the normal critical modifier. For more details, please see Plane Proficiency

  • For Carrier Attacks, they gain a 1.2 critical bonus multiplier for a ❱❱ plane in the top slot and an additional 0.1 for every other ❱❱ plane.
    • For example, a carrier with two max proficiency planes (with one in the top slot) would get a critical bonus of: (1.2 + 0.1) x 1.5 = 1.95.
  • For Carrier Cut-In Attacks, they gain a 1.106 bonus when a ❱❱ plane is selected to participate in the attack and an additional +0.15 if one of the selected planes is in the top slot.

Ammunition Modifier

The damage of the fleet is reduced once their ammunition falls below 50%. This modifier cannot go above 1. The formula use to determine this is:

[math]\displaystyle{ \text{Ammo} = \dfrac{\text{Remaining Ammo %}}{50} }[/math]

Remaining Ammo Ammo Modifier Notes
>50% 100%
40~49% 80% 4th Battle
30~39% 60%
20~29% 40% 5th Battle
10-19% 20%
0% 0% 6th Battle
  • The battle number indicated in the notes assumes only normal surface engagements. Engaging in night battles and other special engagements can change that number.
  • Whatever ammunition modifier applies in day battle carries over to night battle.
  • Maelstroms that reduce ammunition also count towards this modifier.
  • Using AO equipped with Supplies Underway ReplenishmentUnderway Replenishment is a way to medigate ammo penalties.
  • The ammunition modifier affects aerial battle.
  • Once a ship hits 0% ammo, all attacks become scratch damage.
  • Scratch damage is unaffected by the ammunition modifier.
  • Debuffs are affected by the ammunition modifier.

Miscellaneous Damage Modifiers

Scratch Damage

If a special attack is evaded, the target's armor cannot be penetrated, or the ammo count hits 0; attacks will deal "scratch damage" instead, also called "chip damage".

  • Scratch damage is dealt as a percentage of remaining HP calculated using the following formula:

[math]\displaystyle{ \text{scratch} = \text{HP}_\text{current} \times 0.06 + \text{HP}_\text{rand} \times 0.08 }[/math]

  • [math]\displaystyle{ \text{HP}_\text{current} }[/math] is the current HP of the target.
  • [math]\displaystyle{ \text{HP}_\text{rand} }[/math] is a random HP number between 0 and [math]\displaystyle{ \text{HP}_\text{current} - 1 }[/math]

Therefore the maximum possible scratch damage [math]\displaystyle{ \text{HP}_\text{current} \times 0.14 - 0.08 }[/math] and the minimum damage is [math]\displaystyle{ \text{HP}_\text{current} \times 0.06 }[/math]. Meaning scratch damage is generally between 6-14% of current HP.

  • If the target's HP is low, it is possible for the result of the formula to return a result of 0. Remember that all formulas are rounded down.
    • This means the target's HP cannot be reduced to 0 by scratch damage.

Historical Bonus

On almost every Event map, as well as some regular maps (7-4 & 7-5 so far), certain ships, types of ships, equipment, or types of equipment will bring bonuses.

  • Those bonuses are most of the time raw damage multipliers, and sometimes, accuracy bonuses.
  • Bonuses are independent to each ship, so only the ships with any historical bonus or ships equipped with historical equipment will be affected.
  • Bonuses may be applicable to some part of a map only, such as specific phases of nodes.

This mechanic is here to encourage the use of "historically significant fleets and setups".

  • By nature, historical bonuses are arbitrary, so refer to each individual map to see what bonuses are applicable.


Debuffs are a special case that only applies during events. Certain event maps have debuff mechanics that require meeting certain conditions to trigger them. Debuffs can be either a reduction to the enemy's armor or a post-cap damage modifier for the fleet.


  • Debuffs are affected by the remaining ammo modifier.

Overkill Protection

When a ship in the fleet takes more damage than her current HP, she will take a percentage of her current HP in damage instead.

  • The ship must be the flagship OR
  • The ship must not be heavily damaged nor red morale at the start of the battle.
    • If the ship has red morale, she will just have her HP reduced to 1.

[math]\displaystyle{ \text{Overkill} = \text{HP}_\text{current} \times 0.5 + \text{HP}_\text{rand} \times 0.3 }[/math]

  • [math]\displaystyle{ \text{HP}_\text{current} }[/math] is the current HP of the ship.
  • [math]\displaystyle{ \text{HP}_\text{rand} }[/math] is a random HP number between 0 and [math]\displaystyle{ \text{HP}_\text{current} - 1 }[/math]

Therefore, the maximum damage from overkill protection is [math]\displaystyle{ \text{HP}_\text{current} \times 0.8 - 0.3 }[/math] and the minimum damage is [math]\displaystyle{ \text{HP}_\text{current} \times 0.5 }[/math]. Meaning overkill protection will take off between 50-80% of the ship's current HP.

Important Information

  • In general:
    • Overkill protection is most applicable to DDs.
      • The most pronounced effects of overkill protection occur at low HP
      • It is also the primary means of surviving a hit they fail to evade
      • For example, a 32HP DD has a 15.5% chance of being heavily damage by a BB hime, while a 31 HP DD has just a 6.5% chance
      • This has great implications when marrying ships, 36 HP has one of the highest chances of a taiha
    • Odd numbered HP is better when overkill protection is triggered. This is because the damage calculations round down, reducing the likelihood of being knocked down to heavy damage.
    • This mechanism is most applicable to ships at full HP. Once a ship starts taking damage, the utility of overkill protection diminishes
  • As a rule, ships with HP that is divisible by 4 have worse survivability.

Other Information