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Penetration and armour

Checked on build 26052592

On this page

Penetration falls with range
The published rule and its exceptions
Kinetic and HEAT armour
How much damage gets through
The published anchors
Armour value: infantry, helicopters and some planes
Active protection
Shtora and Hardhat
Top attack

In Broken Arrow, how much damage a hit does depends on one ratio: the round's penetration divided by the armour it strikes. From the game's code The game turns that ratio into damage along one of two curves, kinetic or HEAT, and active protection can stop some rounds before they land. From the game's code

Penetration falls with range

Every round has two penetration figures: one at point blank and one at its longest ground range. From the game's data The unit page shows both under Penetration, and the second applies at the distance in the Ground range column. Worked out by this site

Between the two, this site assumes penetration falls evenly with distance, and it uses the far figure at any longer distance. Worked out by this site So a round with penetration 20 at point blank and 10 at its longest range has 15 halfway. Worked out by this site

A weapon's minimum range is not part of this fall-off. Worked out by this site It is a separate dead zone the weapon cannot fire inside. From the game's data Where a weapon has one, the Ground column shows it as a first number. Worked out by this site

The published rule and its exceptions

The game's published rules say kinetic penetration falls off with range, while explosive penetration does not. From the game's own text The data mostly agrees. Of the 640 rounds in the current data, all 145 kinetic rounds lose penetration with range, and so do 8 of the 491 HEAT rounds. From the game's data Those 8 are 20 to 30 mm cannon rounds fired by planes, tagged HEAT, and their penetration halves. From the game's data

Because of them, this site never decides by type. Each round falls between its own two figures, so the data stays the authority. Worked out by this site

Kinetic and HEAT armour

A vehicle has armour on each facing: front, sides, rear and top. From the game's data Each facing has two values, one against kinetic rounds and one against HEAT. From the game's data Each round is tagged in the data as kinetic, such as tank sabots, or HEAT, such as missiles, rockets and high-explosive shells. From the game's data

A hit is measured against the facing it strikes. From the game's code Against a vehicle with facing armour, a kinetic round meets the kinetic armour and follows the kinetic curve below, and a HEAT round meets the HEAT armour and follows the HEAT curve. From the game's code On a vehicle's page, see Kinetic armour and HEAT armour.

The duel puts every shot on the front armour, because its two units stand still and face each other. Worked out by this site

How much damage gets through

The game divides the round's penetration by the armour. Call the result r. From the game's code The curve turns r into a share of the round's Damage, and that share comes off the target's Health. From the game's code

HEAT. The share is r² / (1 + r²). From the game's code That is 20% at half the armour, 50% at equal armour, 80% at double and 90% at triple. It never quite reaches full damage, and never quite reaches nothing. From the game's code

Kinetic. A round that matches or beats the armour does full damage. From the game's code Below that, the share is 2 − 1/r, with a floor of 10%. At exactly half the armour that gives nothing, and below half it stays at nothing. Just above half, the 10% floor applies. From the game's code

Armour of 0 takes full damage from both. Rounds that do not attack armour, such as smoke, ignore it. From the game's code

Worked from those formulas, the share of damage that gets through: Worked out by this site

Penetration ÷ armour	Kinetic	HEAT
0.25	0%	5.9%
0.5	0%	20%
just above 0.5	10%	about 20%
0.75	67%	36%
1	100%	50%
2	100%	80%
3	100%	90%

So the two kinds reward different things. A kinetic round is decisive once it matches the armour and useless at half of it. A HEAT round always does something, but needs about double the armour to do most of its damage. Worked out by this site

Penetration and damage

RoundRange, as the game shows it (m)Armour it meets

The target has an armour value (infantry, helicopters, armoured planes)

Penetration 525; damage that gets through: 100%

The published anchors

A published rules guide, reproducing the official rules, gives 20%, 50% and 80% for HEAT at half, equal and double armour, and 10% at half armour for kinetic. From the game's own text The game's code matches the HEAT figures exactly and the kinetic one only approximately: in the code, exactly half the armour does nothing, and the 10% floor starts just above it. From the game's code Between those points the code and the old fitted curves differ. From the game's code

Until November 2026 this site used curves fitted to the published anchors. They gave HEAT nothing at a quarter of the armour, where the code gives 5.9%, and kinetic 55% at three quarters, where the code gives 67%. Worked out by this site

Armour value: infantry, helicopters and some planes

Some units carry a single Armour value value instead of facings: 6, 8 or 10 on infantry, 10 to 30 on helicopters, and 30 on the A-10C, Su-25SM and Su-25T. From the game's data Other planes have neither. From the game's data In the data, no armour row has both an armour value and facing armour. From the game's data

The game's code treats that value differently from facing armour. From the game's code It counts for every facing and against both kinds of round. And every round that attacks armour then goes through the HEAT curve, kinetic rounds included. From the game's code

So against these units nothing is all or nothing: From the game's code

penetration 20, such as a 40 mm grenade, against armour 10 does 80% of its damage;
penetration 5 against armour 10 does 20%;
penetration 5 against armour 8 does 28%.

For scale, a 5.56 mm rifle round in the current data has penetration 15 or 17 at point blank, falling to 5 or 7 at its longest range. From the game's data

No ground vehicle has an armour value above 0, because its armour is in its facings. From the game's data The unit page shows the armour value for units without facings. Worked out by this site

Active protection

Active protection, or APS, is an ability that stops incoming anti-tank missiles and rockets. From the game's code Ten abilities in the current data are APS, among them Trophy, Arena, Afghanit, Drozd-2 and Iron Fist. From the game's data A unit page lists its system under Active protection. Worked out by this site

The game's code runs it like this:

When it is ready. It is ready while it has a charge left and its cooldown has run out. From the game's code
What it stops. While ready, it guards a box twice the target's size in every dimension. A round the game flags as interceptable that enters the box is stopped, with no damage and no splash. From the game's code In the data, 105 rounds carry that flag: anti-tank missiles and rockets, plus the Hellfire SHORAD. From the game's data
No roll. A ready system always stops such a round. From the game's code
What a stop costs. One charge, then the system's cooldown before the next stop. From the game's code The cooldown is 6 s on every APS in the data. From the game's data
No recharge. Charges come back only by resupply. From the game's code

The shooter's choice. The game's AI loads a weapon's best guided round over its best unguided one only when the guided round's expected damage is at least 1.4 times higher, or 5 times while the target's APS has a charge. From the game's code So a tank facing Arena fires its sabot, and a launcher with only missiles fires into the APS until the charges run out. From the game's code

APS is usually a paid loadout option. From the game's data The T-90M's "Arena APS" option, for example, adds 70 to its cost and fits four Arena charges. From the game's data See loadouts for how options change a unit.

Each system's charges and cooldown in the current data:

System	Charges	Seconds between stops	Box size
APS Trophy NoModel	4	6 s	×2
APS Drozd2	2	6 s	×2
APS Arena	4	6 s	×2
APS Afghanit	2	6 s	×2
Abilities T14 Armata	4	6 s	×2
Smoke x2 APS Default	4	6 s	×2
APS IronFist NoModel	2	6 s	×2
APS US Light	2	6 s	×2
APS US Heavy Model Trophy	4	6 s	×2
Abilities T15 Barbaris	4	6 s	×2

Units with active protection, including those that get it only through an optional loadout:

Units with an active protection system (30)

Shtora and Hardhat

Some tanks and fighting vehicles carry a different defence against guided missiles: Shtora or Hardhat. From the game's data It multiplies an incoming guided missile's hit chance by its ECM value, 0.7 in the data, so a missile hits directly 70% of the time unless a stressed shooter lowers it further. From the game's code From the game's data It appears to work against every kind of missile seeker, because no such system in the data names one. That is our reading of a missing field. Not known: our best reading See missile hit chance for the full hit roll.

Units with Hardhat:

Top attack

A weapon marked Top attack has its hit measured against the target's top facing. From the game's code That is usually the thinnest armour: in the data, the top is the thinnest facing, or tied for it, on every armour row but four. From the game's data The duel does not model this: every shot in it strikes the front. Worked out by this site