What is effective HP and how is it calculated?

Effective HP (eHP) is the total raw damage you can absorb before dying, accounting for your damage mitigation. The formula is: eHP = HP / (1 - Mitigation%). For example, a character with 5,000 HP and 60% mitigation has an eHP of 5,000 / (1 - 0.60) = 12,500. Effective HP is the most accurate measure of true survivability.

How does armor mitigation work in Diablo IV?

In Diablo IV, armor reduces physical damage using the formula: Mitigation% = Armor / (Armor + 10 × Enemy Level × 5). The cap is 85% damage reduction. Additional multiplicative damage reduction sources — like the Damage Reduction affix — stack multiplicatively with armor mitigation, meaning each source reduces the remaining damage rather than the base damage.

How does armor work in Path of Exile?

In Path of Exile, armor reduces physical damage using the formula: Reduction% = Armor / (Armor + 10 × Hit Damage). This means armor is most effective against small, frequent hits and less effective against large single hits. Against a hit equal to your armor value, you receive 50% reduction. Stacking armor with evasion, energy shield, and block creates layered defenses.

Do damage reduction sources stack additively or multiplicatively?

It depends on the game. In most ARPGs, different damage reduction sources — such as armor, resistances, and flat damage reduction — stack multiplicatively, each reducing the damage remaining after previous reductions. Sources of the same type often stack additively. Multiplicative stacking makes each additional source less efficient but avoids hard caps and makes builds more flexible.

What is the resistance cap in Path of Exile?

The default resistance cap in Path of Exile is 75% for all elemental resistances (fire, cold, lightning) and 75% for chaos resistance. The cap can be raised to a maximum of 90% through certain passives, items, and the Brass Dome chest. Completing the campaign applies -30% resistance penalties per difficulty, so most end-game builds need 105%+ total resistance to reach the 75% cap.

Home / Calculators / Damage Mitigation Calculator

🛡️ Defense Optimizer

Damage Mitigation Calculator

Calculate your effective health pool and damage reduction across multiple games

🎮 Select Game

Enter Your Stats

Base Health/Life: 1,000

Armor: 5,000 (35.1% reduction)

All Resistance: 70%

Damage Reduction: 40%

From skills, passives, and items

Fortify/Shield: 0

Temporary health from fortify/shields

Barrier/Absorb: 0

Damage absorption shields

Your Results

Effective Health Pool

8,565

Squishy

Needs improvement

Total Mitigation

88.3%

All sources combined

Damage Taken (from 1000)

117

12% of incoming damage

One-Shot Threshold

8,565

Raw damage needed to kill you

EHP Breakdown

Base EHP: 8,565

+ Fortify: +0

+ Barrier: +0

💡 TIP

All defensive layers multiply together. Stacking different types (armor + resistance + DR) is more effective than focusing on one.

Damage Scenarios

Incoming: 1,000

117

You take 11.7%

11.7% of your HP

Incoming: 5,000

584

You take 11.7%

58.4% of your HP

Incoming: 10,000

1,168

You take 11.7%

116.8% of your HP

Incoming: 25,000

2,919

You take 11.7%

291.9% of your HP

Understanding Damage Mitigation

Effective Health Pool (EHP)

EHP = Base Health / (1 - Total Mitigation)

EHP represents how much raw damage you can take before dying. A character with 1000 HP and 50% mitigation has 2000 EHP.

Multiplicative Mitigation

Total = 1 - (1 - Armor) × (1 - Resistance) × (1 - DR)

Defense layers multiply together. 50% armor + 50% resistance = 75% total mitigation, not 100%. This prevents becoming invincible.

Armor Diminishing Returns

Each game has different armor formulas and caps

Armor effectiveness follows diminishing returns. The first 5000 armor gives more protection than the next 5000. Most games cap armor mitigation at 75-90%.

Optimal Defense Strategy

Balance all defensive layers instead of stacking one. For example, 50% armor, 75% resistance, and 30% DR is better than 90% armor with no resistance. Diversification is key to maximum survivability.