Armor and Effective HP in Dota 2 | Calculator

What is Effective HP in DOTA 2?

Effective HP(EHP) is the total amount of physical damage a unit can withstand based on its armor. It’s a measure of how much damage a unit can take before being defeated.

Armor and Effective HP

For every 1 armor, you get an EHP of 6% added to your initial HP. This is a linear increase, so the EHP increase is just a constant 6% per armor. This happens because armor provides physical damage resistance before dealing with actual damage. To compute your armor use the formula below:

Armor = ( (Base Armor + (Σ Current AGI stat)/6) × (1 – Armor Negation) ) + Bonus Armor

Σ Current AGI stat = Base Agility + AGI gain

Armor Negation is an ability or item that will ignore armor, this is usually removed in percentages.

Unlike some systems where each point of a stat provides diminishing returns, here, each point of armor has the same impact on both health and survivability. Gaining 1 armor always increases the EHP by 6%. Armor is less effective when it’s in negative values. As armor becomes negative, the total EHP decreases. However, it never goes below 50%. This means even with very low or negative armor, a unit can still withstand a significant amount of damage.
Source: https://dota2.fandom.com/wiki/Armor#Effective_HP

Reducing the armor of a Hero from 10 to 0 is more effective than reducing the armor of a Hero from 0 to -10.

Formula to get Effective HP

The first step to getting the Effective HP of a Hero is knowing the damage multiplier that will affect the HP of your Hero like damage reduction and damage amplification.

Damage reduction (DR) = (0.06*Armor)/(1+0.06*Armor)

Damage Amplification (DA) = (0.06*|Armor|)/(1+0.06*|Armor|)

To get the damage multiplier, we need to combine the two formulas:

Damage Multiplier(DM) = 1 – ( (0.06*Armor)/(1+0.06*|Armor|) )

To get the Effective HP the formula is:

Effective HP(EHP) = Current HP / Damage Multiplier

Source of the formulas: https://liquipedia.net/dota2/Armor