How the Effective HP Calculator works

Effective HP is the raw hit that would kill you. Here is how each layer is applied and which constants are still being verified for version 1.0.

checked against 0.5 · 2026-11-11 ← Back to the calculator

Formula

pool = life + energyShield
physical taken = hit × (1 − DR(hit)) × less DR = armour / (armour + K × hit), K = 10 (switchable to 12), cap 90%
elemental taken = hit × (1 − min(maxRes, res) / 100) × less default maxRes = 75%
chaos taken = as elemental, with energy shield counted at half (chaos removes ES at double rate)
EHP(per hit) = the hit such that taken = pool (physical: solved iteratively because DR depends on the hit)
evade = 0.95 × evasion / (evasion + 4 × accuracy) cap 95% (monster chance to hit never below 5%)
avoid = 1 − (1 − evade) × (1 − block) block default max 50%, hard cap 90%, a blocked hit deals no damage
EHP(average) = EHP(per hit) / (1 − avoid)

Why the physical figure is solved, not multiplied

Armour gives a percentage that falls as the hit grows: 20,000 armour removes 67% of a 1,000 hit but only 29% of a 5,000 hit. Quoting "EHP at 50% reduction" would overstate survival against the hit that actually matters. The calculator finds the hit size where damage taken equals your pool, which takes a few iterations of the armour formula.

Evasion

Since version 0.3.0 the game uses a dedicated monster-to-player formula: the monster's chance to hit is 1 − 0.95 × E / (E + 4 × A), so your chance to evade is 0.95 × E / (E + 4 × A), capped at 95%. It applies to attacks and spells alike, except boss skills with a red flash. It is not the player-to-monster accuracy formula (1.25 × A / (A + 0.3 × E)) that many guides still quote for defence. Evasion uses an entropy counter, so over many hits the long-run fraction is exactly this percentage, which is why the "average" column can use it directly. Example: 10,000 evasion against a level-80 monster (1,964 accuracy) evades 95 × 10,000 / 17,856 = 53.2% of hits.

Default monster accuracy by level

Level	Accuracy	Base hit
60	914	181
65	1,114	212
70	1,351	248
75	1,632	288
80	1,964	334
82	2,114	354
85	2,357	385

"Base hit" is the default monster damage per hit before skill multipliers; real hits are several times larger, which is why the calculator reports the hit size you survive rather than assuming one.

Energy shield and chaos

Energy shield is removed before life. Chaos damage does not bypass energy shield in Path of Exile 2; it removes twice as much energy shield per point, so the chaos pool counts energy shield at half. Bleeding and poison bypass energy shield by default, but they are damage over time and outside this calculator.

Block

Block works against all hits since 0.3.0 and a blocked hit deals no damage (stun still applies). The default maximum is 50%, raisable by specific items up to a hard cap of 90%. Red-flash boss skills cannot be blocked. Items that make you take a share of damage from blocked hits are not modelled.

Not included

Damage over time, degens and ailments (armour and evasion do not apply to them).
Recovery: regeneration, leech, recharge, flasks. EHP is a single-hit snapshot.
Conditional layers: guard skills, fortification-style buffs, "damage taken as" conversions. Fold them into "less damage taken" if they are up.
Mind over Matter and similar pool-sharing keystones.

Sources and version (checked 12 November 2026, version 0.5)

Evasion formula, armour ratio K = 10, block maximum 50% and cap 90%, chaos ×2 vs energy shield, evade cap 95%: Path of Building for PoE2 source (CalcDefence.lua, Data.lua, MIT licence), which implements the developer-posted 0.3.0 formulas.
Game constants (max evade 95%, max physical reduction 90%, max resistance 75%/90%), default monster accuracy and damage by level, "chaos removes twice as much Energy Shield", block fully prevents hit damage: poe2db.tw GameConstants, Monster, Energy Shield and Block pages.
0.3.0 patch notes (evasion formula adjusted, evasion and block against all hits) and 0.5.0 patch notes (armour applying to elemental damage via specific sources, no change to the chaos rule): pathofexile.com forum threads 3829081 and 3932540.
Dissenting secondary source: maxroll.gg defence guide lists the armour constant as 12; the calculator lets you switch.
Each constant is tagged VERIFY-1.0 in the code for the 11 December 2026 re-check.

Path of Exile 2 is a trademark of Grinding Gear Games. This site is an independent fan-made tool and is not affiliated with, endorsed by or sponsored by Grinding Gear Games. Game names are used only to describe what the calculators are for. No game art, icons or logos are used. Formulas are compiled from public sources and may lag behind patches — each tool shows the game version it was checked against.