How Does Armor Work in League of Legends?

Armor in League of Legends is one of the many stats a Champion has. It is a base stat, meaning that every Champion gets a certain amount at the start. This amount then increases on a per-level basis. 

There are some Champions which are excepted from this. For example, Thresh gains no Armor per level but accumulates it through the souls he collects with his passive ability. 

Armor is the direct defensive tool against Physical Damage. Physical Damage scales from Attack Damage abbreviated as AD. 

So, how does it work, exactly?

Well, Armor reduces incoming Physical Damage by a flat percentage. This percentage is calculated from a formula Riot has devised that goes like this:

This means that at 25 Armor, there is a 20% reduction, meaning that the enemy will deal 80% of their initial damage.

On the contrary, we can see that having negative Armor actually increases the enemy’s damage. At -25 Armor, the enemy will deal 20% more damage. 

Armor (like other defensive stats) increases the effectiveness of your health. Ever 1 Armor equals 1% more effective health. The formula for calculating Effective health goes something like this: 

This means that a unit with 60 Armor has 60% more HP against Physical Attacks. If the unit, for example, has 1000 HP – it would take 1600 Physical Damage to kill them. Here we can clearly see just how important having high Armor is – it doesn’t only decrease the enemy’s damage but also increases the effectiveness and worth of your HP. 

Armor also has a gold value of 20 gold per point. 

Also read: Best Mobile ADCs in League of Legends

Can Armor be negated/mitigated?

Yes, there are countermeasures to Armor. 

Namely, there are three – Armor Penetration, Armor Reduction, and Lethality

Armor Penetration ignores a percentage of the target’s Armor. For example, if a target has 100 Armor and the attacker has 30% Armor Penetration – their Armor value will effectively be 70. 

The Armor Penetration stat stacks multiplicatively, meaning that the values are multiplied with each other rather than stacked all together.

 If you, for example, were playing as Darius, who has 30% Armor Penetration on his E and built Lord Dominik’s for an extra 35% – the result would be 51% Armor Penetration and not 65. 

Lethality ignores a flat amount of the enemy’s Armor. Lethality is unique in the fact that it scales with level. Here comes the math again.

Flat Armor penetration = Lethality x (0.6 + 0.4 x level / 18) 

At level 1, according to the formula, Lethality grants 60% of its amount as Armor Penetration that scales up to 100% by level 18. The Zed mains better learn this calculation by heart to better understand their power spikes. 

Lethality stacks additively, just like Armor itself does. It isn’t multiplied, and the values are not shifted like with the percentage-based Penetration. 

And, last but not least, there’s Armor Reduction. This one is pretty straightforward – the target’s Armor is reduced by either a percentage or a flat amount. The Flat reduction stacks additively, like Lethality, and the percentage one multiplicatively like Penetration. 

The difference between these two is that flat reduction goes beyond 0, taking the target’s Armor into the negatives – increasing damage dealt to them by Physical Attacks. 

Percentage-based reduction and, by extension, Penetration are not applied to targets with an Armor value higher than 0. 

You can see how powerful flat reduction and flat Penetration can be. Still, against very high Armor targets like Rammus, I advise combining both to get the best Penetration and Reduction results.

Finalizing Thoughts

Armor is your primary defense against Physical Damage in League of Legends. Having tons of Armor means that your HP immediately becomes more potent and is a lot more than it says. 

Of course, Armor does nothing against Magic Damage, and we will cover that in another guide. 

At this moment, make sure to study the Armor mechanic to understand better how to use it and go against it. 

These guides take a lot of time and effort to make, so leave feedback to help us improve them. Keep a keen eye out on our website for more League of Legends-related content such as guides, lists, and articles. 

Big thank you to for providing the formulae and statistics used in this guide. Without the League wiki, this community would undoubtedly be in a dark place – so make sure you check that site out as well. 

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