I'd like to ask, what is the max armor penetration I can get? By that I mean, not what is the max I can get from items, runes and masteries but what is the max available. I heard that the max is 40% and no matter how much more armor penetration you have it won't matter. I'm not totally sure about that though.

I have 19 armor penetration from runes and 6 from masteries, so in total I have 25 from the start of the game. If I take Last Whisper (which gives me 35% more), Black Cleaver (10% more) and Youmuu's Ghostblade (20%) I will have 90% armor penetration. Will all of it count or only 40% of it while the rest won't even matter?

  • The second question there is different enough from your first question that you really should remove it and ask it as a separate question entirely. May 14, 2014 at 18:57
  • I will do that then.
    – zETO
    May 14, 2014 at 19:03

4 Answers 4


Let's get some things clear: There is no cap on Armor penetration and there are not too many Items that provide it.

So let's start off with the runes and masteries. From runes you can get a total of 19.2 ArPen while from masteries you have 6% Armor Pen. Now if you pick darius (Champ with most armor penetration) You can start the game at level 1 with 19.2 and 11% ArPen.

If you continue your ArPen journey you will have to buy A Black Cleaver(10Flat), A Yomuus Ghostblade(20Flat), a Brutalizer(10Flat) and a Last Whisper(35%). With darius and his E maxed (25%) + all the runes this gives you a total of 69.2 Flat and 48.6% since percentage armor penetration stacks multiplicatively like Soulcreeper has pointed out in his answer.

That's a pretty huge amount but I wouldn't consider it viable because it's purely glasscannon and has no real use to the team. It's usually better to either go for some crit or survivability depending on the champion you're playing.

  • I would add that this answer doesn't show any limit either, which is a good wrap up of existing ones. May 14, 2014 at 19:44
  • Pretty satisfying explanation on what I asked. Would you mind explaining me a little what I see when I press "c" in game, on the Armor penetration? I see something like 28/40% ( The numbers are completely random ). What does this first 28 means? I get that I have 40 armor penetration so far, but I don't get the 28.
    – zETO
    May 14, 2014 at 20:05
  • @zETO usually you should see a flat amount and a percentage which resemble ... well ... flat and percentual penetration
    – Jutschge
    May 14, 2014 at 20:07
  • I don't really understand what that flat amount is. Let's say that my flat armor penetration is 60. Does this mean that I'm reducing the armor of the enemy by 60 + the percentage of armor penetration that I have? Or I got something completely wrong?
    – zETO
    May 14, 2014 at 20:19
  • 2
    If the enemy has 140 armor, and you have a flat 40 armor pen, they will have 100 armor left for your damage to fight through. If you have 40% armor pen, they will have 84 armor left. If you have 40% armor pen and 40 flat armor, it will be (140 * .6) - 40 = 44.
    – dphil
    May 14, 2014 at 20:25

Armor reduction (which is provided in percentiles and usually stacks on hit) is vastly different than penetration. What makes reduction unique is that it is required for penetration to truly have a noticeable effect. You apply X% of armor reduction before applying X-Value of armor penetration. The math can be a bit confusing for some people to figure out because it's exponential. Honestly the exponential part doesn't matter, what matters is that it IS exponential which means there is a chance for multiplicities, there in armor penetration and reduction are dependent on each other to see a vast difference from seeing them at work separately. Also keep in mind, any damage over the enemies armor (obtained through the mix of penetration and reduction, which together is known as peeling) is true damage. Some people mistake what true damage is. Some think that true damage can only happen when using an item or an active that says true damage specifically. All that true damage means is that the specified damage is ignoring all resistances, unless prevented. (I.E. Barrier/Regenerative Healing/Block/Dodge etc. Now that I have explained what true damage is typically associated with, I will explain the correlation between armor pen, reduction, and true damage. Reduction enables armor penetration to multiply itself and eventually with enough reduction to "pierce" through armor. So the equation is basically this. Reduction + Armor Penetration = X -Armor Value + X True Damage, the True damage is obviously Attackers Damage - Defenders Remaining HP. This may seem op, and it can be in the right team comp because it allows for the strongest initiation possible in a team fight, however, it can be countered by building items that negate attacks, slows attacks, reflects damage, or creates a barrier. This may not seem like much of a counter because all it takes is time for the attacker to break though, however it provides a window for burst and dps to melt the glass cannon. To be able to counter this you would need your tanks to avoid damage until after the enemy is burst down and come in for the clean up before the enemy can peel and finish off the tank/fighter/bruiser. I personally have had no problems steamrolling with an armor penetration and reduction focused build,but it does make you a glass cannon, similar to an ap carry that only builds offensive items.

I know I rambled some, but there are distinct differences between the two features and also a huge difference when not using them along side each other. if you're not building reduction, don't bother building armor pen because it will be negated by stacking armor.

Champions that I have found work well with armor pen include: Vi/Darius/Xin/Renekton/Talon/Sivir (plus several other adc's ofc)/Noct/Olaf....Many others as well but I don't feel like going through a list. lol You can figure it out after playing around with it a little. Vi/Darius are top pics because of their natural peeling abilities, Talon not too far behind but less opportunistic than Vi and Darius because of thelowe rchances of aplifying the peeling effect. He is however a great burst/peel combo. :)


Definams answer is wrong because the max flat armor Pen is 59.2 and flat armor pen is getting applied after the % armor pen and if you also have 5 cleaver stacks the way you calculate is:

a = Armor
p = Flat Pen
b = Black Cleaver
i = Ignored Armor (% armor Pen)

We search for X = Armor after all pen

[a * (100% - b) * (100% - i)] - p = x

For example with these stats:

a = 200    p = 40    b = 25%    i = 35%

we'd have:

(200 * 75% * 65%) - 40 = 97.5

97.5-40 = 47.5

If I now take the maximum Armor Penetration possible

a = 200     p = 59.2    b = 25%    i = 48.6%

the actual armor of the target would be:

(200 * 75% * 51.4%) - 59.2 = 77.1

77.1-59.2 = 17.9

So with maximum Armor Pen on Darius you do nearly True DMG to Enemies with 200 Armor since they technically only have 17.9 armor left. And Enemies with under 154 armor recieve True dmg.

Armor Pen doesn't stack, it's being multiplied so the maximum amount you can have there is

0.35*1.06*1.25 = 0.486

The other two answers are completely wrong because the brutalizer armor pen is a passive and does not stack with Black Cleaver. In general, you should read up on items before going into a strategic route like armor pen. It's just like reading the directions on a map, not difficult just not many people look at them word for word.

So basically the max cap you could get with a champion like Darius would be 49 Flat with 56% pen.

Ex: 200 armor - 49 = 151*.56 = 84.56 armor.

The percentage of difference in this of actual damage dealt is good but not fantastic as 200 armor blocks about 77% damage and 84 would be around 55% or so.

  • The fact that it's a UNIQUE passive doesn't mean it can't stack with other items, but with another copy of the same.
    – Arkl1te
    Oct 25, 2014 at 22:18

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