COMBAT
Damage Formula Calculator
Use this game damage formula calculator to tune one hit at a time. Adjust base damage, attack scaling, armor, mitigation, and crit settings; compare normal, critical, and expected damage per hit.
COMBAT BALANCE
Tune your damage formula
Enter a non-negative base damage value; decimal inputs are allowed.
Damage formula guide
Start with the base hit, then change one modifier at a time. The live normal, critical, and expected damage-per-hit results make it easier to compare balance changes before applying your game’s own rounding and damage rules.
The formula
This calculator uses a common action-RPG model: base damage × (1 + attack bonus / 100) × 100 / (100 + defense) × (1 − flat mitigation / 100). A critical hit multiplies that result; expected damage per hit is the normal result × [1 + (crit chance / 100) × (crit multiplier − 1)].
The exact numbers are yours to tune — the point of the tool is seeing how sensitive the output is to each knob. Small defense changes matter less at high values; crit chance and multiplier compound together.
Reading the results
Normal hit is the modeled non-critical result. Critical hit is the modeled critical result. Expected DPH is the long-run average per hit when each hit has the same independent crit chance.
With the defaults, the unrounded values are 92.3 normal, 138.5 critical, and 96.9 expected damage per hit.
Normal and critical hits are displayed to the nearest whole unit; Expected DPH keeps one decimal.
The model does not apply your game’s per-hit rounding, resistance types, or skill-specific order.
Tip: Balance around expected damage, not max damage. A 10% crit chance at 2× adds 10% to the average damage per hit before any game-specific rounding.
Frequently asked questions
What is a good armor curve?
A common starting point is 100/(100+armor): 50 armor removes about 33.3% of incoming damage, and 100 armor removes 50%. It is one model, not a universal rule; match the formula and scale your game uses.
Should I use flat mitigation or armor?
Armor reduces damage by a fraction that depends on the armor curve; flat mitigation applies a separate percentage multiplier. Use the rule your game actually implements, and avoid applying both twice to the same defense layer.
How do I balance crit?
Compare expected damage per hit with and without crit. If one weapon has higher crit chance but lower base damage, the average helps compare them over many independent hits.
Privacy note: damage calculations happen in your browser. Nothing is uploaded.