RPG Damage Calculator: Armor, Crits and Average DPS

Enter base damage, armor, penetration and crit rate to get the real damage per hit and the expected average.

RPG damage formula: armour, penetration and critical hits

The tool applies a diminishing-returns armour reduction: reduction = effective armour / (effective armour + 500), after removing the penetration percentage. The average damage per hit weights the normal hit and the critical hit by the crit rate. With 1,500 attack, a 250% skill ratio and 400 armour with 25% penetration, a normal hit deals 2,344 points.

The formulas used

  1. Effective armour = armour × (1 − penetration %), never below 0. Only percentage penetration is modelled, not flat penetration.
  2. Damage reduction = effective armour / (effective armour + 500).
  3. Normal hit = ATK × skill ratio × (1 − reduction).
  4. Critical hit = normal hit × crit damage %. The value you enter is the total multiplier: 180% makes a crit 1.8 times the normal hit, not 2.8 times.
  5. Average damage = normal hit × (1 − crit rate) + critical hit × crit rate, with the rate clamped between 0 and 100%.
  6. Effective HP multiplier = 1 / (1 − reduction) = 1 + effective armour / 500.

Worked example (default values)

ATK 1,500, ratio 250%, crit rate 65%, crit damage 180%, armour 400, penetration 25%. Effective armour: 300. Reduction: 300 / 800 = 37.5%. Raw damage 3,750, so 2,344 per normal hit (rounded). Crit: 2,343.75 × 1.8 = 4,219. Average: 2,343.75 × 0.35 + 4,218.75 × 0.65 = 3,563. The target takes hits as if its HP were multiplied by 1.60.

Limits

The constant 500 is the tool’s own choice; each game sets its own value or uses a different formula, so the results are for comparing builds, not for reproducing a specific game. Flat defence, shields, elemental bonuses and attack speed are ignored, and the “DPS” figure is an average per hit, not per second.

Frequently Asked Questions

How does armour reduce damage in this calculator?

Reduction = effective armour / (effective armour + 500). So 500 effective armour blocks 50% of damage and 1,000 blocks 66.7%: each extra point of armour is worth slightly less than the one before.

Should I raise crit rate or crit damage?

Average damage = normal hit × (1 + rate × (crit damage − 1)). At 65% rate and 180% crit damage the average gain is 52%; going to 75% rate gives 60%, going to 200% crit damage gives 65%. The better choice depends on your starting values, which the tool lets you compare.

What does armour penetration do?

It removes a percentage of the target’s armour before the reduction is calculated. On 400 armour, 25% penetration leaves 300 effective armour and lowers the reduction from 44.4% to 37.5%.

What is the effective HP multiplier?

It is 1 / (1 − reduction), which equals 1 + effective armour / 500. At 300 effective armour the target survives as if it had 1.6 times its hit points.

Is this tool really free?

Yes, all tools on Kristools are 100% free and accessible without registration.

Is my data protected?

Yes. All processing is performed directly and securely inside your browser. No personal data is sent to our servers.