Quote Originally Posted by NotThatGuy View Post
Just figured I'd point out some errors in what is noted here. Neither of the people quoted seem to have taken the time to look up the actual formula used for the game, which are available on the official wiki.

Damage reduction is countered by armor pen. The relevant formula being the damage dealt formula which is:
Damage Dealt = Damage * [1 - EffectiveArmor - DamageReduction + Penetration] * (1 + CriticalMultiplier)
Note that the number in the [] cannot exceed 1, convert percents to decimals for variable. Also you only add the crit multiplier on a critical hit.
As can be seen by this formula, Penetration directly counters Damage reduction on a 1 to 1 basis. Effective armour I will cover below.

As for the bit about evasion being countered by +100 accuracy skills, this is generally accurate, as hit chance is determined by accuracy - evasion, and rarely will a tank won't come close to exceeding 100 evasion drop that result below 100 after the 100 is added unless said tank is using a skill that pumps evasion similarly high, but much the same could be said of damage reduction tending to be countered by skills that massively pump pen (of which there are a few, though admittedly not so many as there are ones that pump accuracy).

This comment is wrong, in that armour is a percentile reduction. The relevant formula here is the effective armor formula:
Effective Armor = 100 - (25900/((Armor/1.01) + 260))
Note that based on this formula, 0 armor provides about 0.4% effective armor, while 100 armour provides a little less than 28% effective armor. As can be seen in the formula for damage above, effective armour is the same as damage reduction in how it impacts damage, and is directly countered by penetration.
Interesting that the formula is like that.... I was told that armour was flat reduction and it seemed to be that way in game so I just believed what I was told. Even doing the math it seems that going for a pen emblem with at least 30% pen is actually better then crit damage for consistent damage if you have less than 30% crit chance. After 30% crit chance 100% crit damage (1 decent crit damage emblem) is stronger than pen in most situations.

To get these figures I used 100 armour as the amount because all but heavy tanks and a few TDs have just above or less than 100 armour at max level. Even tho higher pen is easy to get with 1 emblem it does not add as much as you might think because against most tanks higher than 30% is the same as 30% because you cannot do extra damage with pen only back up to 100% and 30% pen is 100% damage on 70-80% of the tanks in the game.

So I stick by my statement that crit / crit damage are better stats than pen, especially in high numbers since even 300 armour (which no tank has even with skills, 250 is about the highest) is only a 56% reduction to damage and 44% of a 150% crit damage crit is still 110% of normal damage. Since 200%+ crit damage is fairly easy to get that becomes 132% vs 300 armour and more vs everything else. This is the reason that arty does so much damage even to high defence tanks, my 300 armour HTs still take 1500 damage from a S51 skill hit and that is with their defence skills active.