World of Tanks - Penetration, Damage, Modules, and Ramming

An informative guide on World of Tanks game mechanics for all your destructive needs!

Practically everything surrounding damage is what we’re focusing on in this Battle Mechanics article – Penetration, Damage, Module Damage, and Ramming. Many players dismiss damage mechanics as a very obvious and straight-forward system that they don’t need to pay attention to, but there are actually some interesting interactions and formulas used that could give you the edge you need over your opponent.

Check out my View, Spotting, and Signal Range guide to fully understand how you can one-up your competition in the vision-based game.


Effective Armor Thickness

An example of various impact angles against a 100mm thick armor plate.
An example of various impact angles against a 100mm thick armor plate.

To understand penetration, you must understand how both nominal and effective armor values work in World of Tanks. The “nominal armor thickness” refers to the thickness of a plate at a 0 degree angle from the cosine or “normal”, i.e. absolutely perpendicular to the armor plate. “Effective armor thickness” refers to the increased amount of armor a shell has to penetrate based on the angle of impact against the normal. These values (displayed in intervals of 10°) are as follows:

Impact Angle (°) Effective Armor Thickness (%)
0 100
10 101.54
20 106.42
30 115.47
40 130.54
50 155.57
60 200
70 292.38
80 575.88
90 NA

As can be seen, there is an exponential increase in armor thickness as the impact angle increases. The 10° difference between 0 and 10 degrees barely increases the effective armor thickness over 1.5mm, whereas the 10° difference between 60 and 70 degrees is almost as great as the 60° difference between 0 to 60 degrees. It should be noted that AP and APCR rounds ricochet at angles greater than 70°, whereas HEAT rounds ricochet at 85°.

To calculate the effective armor thickness of a plate, use either a helpful tool like Panzer World’s Relative Armor Calculator or use the following formula:

nominalArmorThickness /cosine(impactAngle) = effectiveArmorThickness

If we take the Object 140, for example, we know its upper plate is 100mm thick and angled at around 64 degrees, giving it an effective armor thickness of around 228mm. We can check to confirm this.

Using this information, our calculation would be:

100 / 64cos = 228.1172…

Or 228mm when rounded down. Get out your scientific calculator and try it yourself, it’s like magic. The Penetration statistic then refers to how far a shell can penetrate the thickness of a plate’s effective armor at 100m, +/-25% as per the RNG effect placed on shell penetration. This means a shell with 100mm of penetration can roll as low as 75mm of penetration, meaning it can’t penetrate anything over 75mm in effective thickness, or it can roll as high as 125mm and can therefore penetrate anything 125mm in effective thickness or below. Simple.

Once you understand this, I’d strongly recommend reading my guide on Overmatch, Normalisation, and Ricochets for further penetration mechanics, including some very advantageous information that can allow you to dominate all types of opponents, namely Mediums and Heavies.

Penetration Loss over Distance

The ‘Penetration Nerf’ tested in the Sand Box
The ‘Penetration Nerf’ tested in the Sand Box

Yes, I specified at 100m in the previous section because Armor Piercing variant shells (AP and APCR) can lose penetration over distance past the range of 100m, where higher tier guns typically lose less penetration over distance, and APCR rounds more so than AP providing it’s Premium APCR rather than standard APCR found on many high-tier Medium Tanks, for example.

This may seem like a pretty big deal at first glance, as your Leichttraktor at Tier 1 can lose up 17.5% of its original penetration value with its stock gun by using AP, but 51.4% using APCR rounds. “Whoa!” you might be thinking. “APCR rounds are worse than AP rounds at long range!” you could be mistaken in assuming. Well, not really. The numbers certainly imply that, but when you read into it and do a little math you realise the Leichttraktor’s stock AP rounds have 40mm of penetration at 100m, and if they were to drop off by 17.5% they’d sit at 33mm of penetration, whereas its APCR rounds with over a 50% drop off would drop down to just shy of 36mm of penetration, making APCR around just as good as AP in the worst case scenario when accounting for the normalisation difference between the two ammo types

It’s the same case with higher tiers. The mighty Maus at Tier 10 loses up to around 2% of its penetration value with AP, and 15.4% with APCR. This translates to its AP dropping from 246mm to 242mm, and its APCR from 311mm to 263mm at the absolute maximum (and we’re talking distances beyond your render range even reaches). Basically, no matter what people may tell you, penetration drop off doesn’t particularly matter in most cases, and it’s not a reason to drop your Premium ammunition for standard unless you want to save some credits by doing so because it’s usually still better regardless.

When it comes to High Explosive variants (HE, HESH, HEAT), no penetration drop off occurs as these rounds deal damage by detonating upon impact, rather than through kinetic energy as is the case with Armor Piercing variants. In case you were interested, the Penetration RNG of +/-25% applies at the point of impact, i.e. after any penetration drop off may have occurred.

Double Penetration

Once a shell impacts a target, its flight path continues for a distance of its shell calibre * 10 (so a 100mm gun would continue for 1m, a 170mm gun would continue for 1.7m, etc.). This is important because a shell must penetrate its target and continue on in order to damage internal modules and crew members – more on that later. Not only this, but if a round ricochets the enemy’s armor it can continue travelling into another enemy – or, hopefully not, a friendly – within close proximity.

There’s also the matter of penetrating spaced armor vs hull armor – with something like the cheese wedge, I mean Strv 103B, it has a ‘HEAT shield’ or strip of spaced armor along the upper hull to detonate explosive rounds before they reach the main hull. Due to the sheer angling and therefore distance between parts of the hull and spaced armor, however, it’s entirely possible that an AP-variant round simply wouldn’t be able to reach the Stridsvagn’s hull armor. The distance between the top part of the spaced armor shield and the part of the hull connecting the UFP and roof is around 5m.

When calculating Overmatch, the nominal armor thickness of the spaced armor is ignored and only the nominal thickness of the hull is used in the formula.

Damage Mechanics – Armor Damage

There are two types of damage in World of Tanks; Armor Damage, and Module (and crew) Damage. In this section we’ll focus on the former.

Armor Damage refers to the type of damage most players are familiar with – the damage you deal to an enemy Tank’s health pool upon a successful penetration. In the case of AP, APCR, HEAT, and penetrating HE or HESH rounds it’s as simple as that – if you penetrate an enemy you deal your average shell damage +/-25% as per the Shell Damage RNG applied to every damage-dealing shot, similar to how Penetration has its own RNG. If you don’t penetrate, you don’t.

In the case of a non-penetrating HE or HESH round, however, things can be a little different and knowing exactly how it’s calculated can be useful. As we all know, not penetrating an HE round will cause some splash damage to the target based on your shell damage, but how it’s actually calculated is a mystery to most. There’s actually a set formula in place when a non-penetration with HE occurs:

actualDamage = 0.5 * nominalDamage * (1 - ImpactDistance/SplashRadius) - 1.1 * nominalArmorThickness * SpallCoefficient

Now what does any of that mean? Well, let’s create a scenario. We have two IS-3s duking out against each other, and one has decided to load HE rounds against the other’s thin roof armor (not something I’d recommend if you understand Overmatch mechanics, but let’s use it for the example). The IS-3’s BL-9 has 530 alpha damage upon penetrating, with 68mm of penetration. The IS-3’s roof is 20mm thick angled at 85 degrees, resulting in 230mm effect armor against rounds without normalization such as HE. Because of this, the HE round will never penetrate the IS-3’s roof armor, and will instead calculate a value for splash damage using the above formula. The formula tells us that our actual damage depends on half of our average damage upon penetrating, multiplied by 1 * your impact distance divided by your shell’s splash radius (due to the fact that our HE rounds are hitting directly onto the weak spot and don’t have to travel, this is irrelevant)), minus 1.1 * the 20mm nominal thickness of the IS-3’s roof, * whether the IS-3 was using a spall liner or not (in this scenario he wasn’t). Our total calculation would look like:

0.5 * nominalDamage - (1.1 * nominalArmorThickness) = Average Splash Damage


0.5 * 530 - (1.1 * 20) = 243

So our average damage dealt with an HE splash is 243, +/-25% as per the Shell Damage RNG applied makes the minimum roll 182, and the maximum roll 304 – as can be seen by the image below.

Every damage roll is between our calculated minimum and maximum damage rolls.
Every damage roll is between our calculated minimum and maximum damage rolls.

If the HE round impacts spaced armor, a second calculation (identical to the formula above) occurs for the underlying hull armor, however it uses the post-reduction damage as the nominalDamage, meaning the resulting damage is typically non-existent or very low.

Now, if you didn’t understand all of that, don’t worry. You don’t need to remember this exact formula in game (I would guess that nobody does), or do the math in the heat of the moment, it’s just nice to understand how everything works together. What should be noted is whether or not you’re hitting the target, the distance between your shell’s explosion and the weakest part of the armor, your HE alpha damage, and the enemy’s nominal armor values. It’s not uncommon to deal maximum possible damage by shooting underneath a heavily armored Tank like a Super Heavy with high calibre HE rounds to splash their “belly” armor, or by shooting their turret face to splash into their soft hull roof.

Module and Crew Damage

This is the other form of damage shells are capable of dealing. Each module has a specific health pool, and shells have their own specific module damage. Damaging a module doesn’t have any relation to damaging the tank’s health pool, and damaging the tank’s health pool doesn’t have any relation to a module’s health pool.

However, as stated in the Double Penetration section, a shell’s flight path does not end after initial impact so it’s entirely possible to damage both a module and penetrate a tank’s hull armor (such as shooting at the frontal drive wheel of a tank to de-track and damage the tank at the same time), and likewise it’s entirely possible to penetrate the hull armor of a tank and also damage internal modules or crew members. Crew and modules have no armor value, so if a shell connects with them they will take damage. While tracks act as spaced armor for the hull, the module itself doesn’t have any armor.

Every gun in the game has a set damage value for module damage based on their shell calibre. 75mm guns, for example, have a module damage value of 100, regardless of their Armor Damage value (typically around 135 damage). 105mm guns, however, have a module damage value of 150, separate from their Armor Damage value of 320 in the case of the Tiger 2 and Löwe, or 390 in the case of many Tier 10 Medium Tanks. This module damage value is not effected by shell type, such as AP vs HE.

Every crew member has a flat 33% chance to get knocked out upon contact with an AP, APCR, or HEAT round. When it comes to explosions from rounds like HE, things change a little. The chance to knock out a crew member with HE drops to 10%, but a greater number of modules and crew members are able to be effected by an explosion. If the shell exploded upon a vehicle, a 45° cone originating from the point of impact simulates the blast wave entering the tank, and will potentially effect any crew members and modules that it encounters. Should the explosion occur off of the tank, such as when firing an HE round underneath the tank, or artillery landing a shot nearby, no such blast wave simulation is created, and the area affected is based on the original splash radius. In the event that every crew member in your tank gets knocked out, your vehicle is disabled and you effectively get destroyed.

“Yellow” Module Damage

A module turning “yellow” means that a module has been hit and has lost 50% of their health or more, often referred to as “critically damaged” or simply “damaged”. Crew members cannot turn “yellow”, and instead act immediately as though they’re knocked out. Effects of a critically damaged module can be:

  • Fuel Tank – Subsequent hits are more likely to start a fire. The Fuel Tank’s base chance to start a fire upon taking damage is 50%, and fires can even start without the module’s health dropping below 50% and technically becoming critically damaged.
  • Turret – 50% reduction is turret traverse speed.
  • Gun – 50% increase in dispersion and decrease to accuracy.
  • Engine – 50% Engine Horsepower.
  • Ammo Rack – 50% Reload speed.

Other modules, like your tracks or range finder, have no negative effects upon being damaged other than having fewer hit points remaining and therefore being easier to destroy in subsequent shots.

“Red” Module and Crew Damage

A module turning red means it’s destroyed. As previously mentioned, a Crew member can only become “destroyed” or more accurately injured/knocked out, and don’t have multiple stages of effectiveness based on health like modules do. Effects of a destroyed module are mostly obvious:

  • Tracks: Vehicle is immobilised.
  • Rangefinder: Spotting range is reduced by 85%, or less with the Recon skill.
  • Fuel Tank: A fire is guaranteed to start.
  • Turret: Turret traverse is disabled.
  • Gun: Unable to fire, unable to change elevation.
  • Engine: Horsepower reduced to 0. This means you can’t accelerate in either direction, or traverse without assistance, though you will still move if on an incline/if you already had momentum built.
  • Ammo Rack: Vehicle is destroyed providing there are rounds remaining inside the tank. Turreted Tanks will have their turrets blown off.

Injured crew members will stay in such a state until healed by the use of a First Aid Kit. Destroyed modules will repair over time to the “yellow” state based on their repair speed.

Saving Throw

Saving Throw is a mechanic known to practically nobody, but has silently protected them against losing their ammo rack many a time regardless (or, depending on whether you’re a glass half empty kind of guy, denied them many ammo rack destructions).

Saving Throw refers to the chance a module will actually take damage upon being hit. Each module has a set value for this, where 100% is guaranteed to do damage and 0% is impossible to deal damage:

  • Suspension: 100%
  • Engine: 45%
  • Fuel Tank: 45%
  • Observation Device: 45%
  • Radio: 45%
  • Turret Ring: 45%
  • Gun: 33%
  • Ammunition Rack: 27%

Crew members are also affected by saving throw, though that was detailed at the start of the “Module and Crew Damage” segment. The short of it is all crew members have a flat 33% chance to be knocked out upon getting hit by an AP, APCR, or HEAT round, and a flat 10% chance upon getting hit by an HE explosion.

Fire Damage

Fire! Nothing quite like it to start a panic in the poor heart of a pubbie who forget their Automatic Extinguisher. Fire damage causes Armor and Module/Crew damage in constant game ticks, the amount is tied to your specific tank but the specifics aren’t listed in game. The duration of the fire is based on your tank, the Firefighting and Preventative Maintenance Crew Skills, and whether you’re running an Automatic Fire Extinguisher or not (you should be).

Ramming Damage

Get your E 50 M’s ready, it’s ramming time. Ramming tanks is incredibly fun, and you should always do it unless you’re French and not called the “AMX 50 B”. Well, that wraps it up for this guide… what? You want to know how ramming works? Fine, I guess.

Read: 5 Best Tanks for Ramming

Ramming actually causes an explosion upon the point of impact, and damages both tanks involved in the ram as a result. The amount of damage created is based on the following formula:

0.5 * combinedWeight * relativeSpeed^2

Or simply both tanks’ weights put together, multiplied by how fast you were smashing into eachother. Once the damage has been calculated, the damage distribution is affected by the following formula:

1 – individualWeight/combinedWeight

For example, if your combined weight is 100 tonnes and you weigh 60 tonnes, you’ll only take 40% of the damage. The actual damage calculation then follows the same formula used for HE rounds mentioned previously, hence the reason that Light Tank you squished with your overweight bundle of Kruppstahl lost almost all of its health whereas you took practically none. Similarly to with HE explosions, a spall liner reduces the amount of damage you take from ramming, as does the Controlled Impact Crew Skill.

To get maximum efficiency out of your E 50 M rams, squish puny small tanks rather than trying to pick on a Maus (I know, the name is misleading, sneaky Krauts). To avoid angry E 50 M drivers, I’ll first ask you to politely accept it, but other than that I guess you could try to move in the same direction as the incoming bundle of fun (away from it, rather than sitting still or driving towards it) to reduce your relative speed. But come on, just let me ram you.

That actually is the end of this Battle Mechanics Guide. Another long one, but I hope you found it useful and informative. What would you like to see next in the Battle Mechanics series, and more importantly, what’s your favorite vehicle to ram in?


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