Dota 2 Armor & EHP Calculator
Calculate your Effective Health Pool (EHP), physical damage mitigation, and see exactly how armor corruption impacts survivability.
Hero Attributes
Combat Analytics
Decoding the Dota 2 Armor Formula
Unlike many modern MOBAs that use flat linear scaling, Dota 2 employs a very specific mathematical formula to calculate armor effectiveness. Understanding this formula is the key to surviving physical burst damage from carries like Phantom Assassin or Templar Assassin.
The 0.06 Armor Multiplier
Every point of armor in Dota 2 provides exactly 6% of your Maximum Health as Effective Health (EHP) against physical damage. This means armor scaling is linear in terms of survivability. 10 armor gives you +60% EHP. 20 armor gives you +120% EHP. The actual formula the game engine uses to calculate the damage reduction percentage is:
For example, if you have 10 armor, the reduction is (0.06 * 10) / (1 + 0.6) = 0.6 / 1.6 = 0.375. You take 37.5% less physical damage.
What is EHP (Effective Health Pool)?
EHP is the most critical metric for tankiness. If you have 1,000 HP and 50% damage reduction from armor, an enemy must deal 2,000 raw physical damage to kill you. Your EHP is 2,000. Building raw HP (like a Heart of Tarrasque) makes your existing armor more valuable, and building armor (like an Assault Cuirass) makes your existing HP more valuable.
The Danger of Negative Armor
When items like Desolator or spells like Slardar's Corrosive Haze drop your armor below zero, the formula creates a Damage Amplification effect. If your armor is -10, you take roughly 37.5% more physical damage. In our calculator, you will see your EHP drop below your raw Maximum HP when armor turns negative.
Does armor suffer from diminishing returns?
In terms of Damage Reduction %, yes. Going from 0 to 10 armor gives 37.5% reduction. Going from 10 to 20 armor only gives an additional 18% reduction. However, in terms of EHP, there are NO diminishing returns. Every point of armor always adds 6% of your max HP to your physical effective health.
Does armor protect against magic damage?
No. Armor exclusively mitigates Physical damage (from basic attacks and certain physical spells like Bristleback's Slithereen Crush). To survive magic damage, you need Magic Resistance items like Pipe of Insight or BKB.
Should I buy HP or Armor?
It depends on your current stats. As a general rule of thumb, if you have very high health but low armor (like Centaur or Pudge), buying a Platemail provides massive EHP. If you have high agility/armor but low health (like Terrorblade), buying raw HP provides a better survivability boost.
Read Also: