Critical Hit Calculator
Calculates average effective damage factoring in your critical hit chance and multiplier. Use it to evaluate gear choices and optimize damage output in RPGs and action games.
About this calculator
When attacks can critically hit for bonus damage, the true average damage per hit is higher than the base damage alone. The formula for average effective damage is: effectiveDamage = baseDamage × (1 + (critChance ÷ 100) × (critMultiplier − 1)). Here, critChance is expressed as a percentage (e.g., 30 for 30%), and critMultiplier is the factor applied on a crit (e.g., 2.0 for double damage). The term (critMultiplier − 1) represents the bonus damage above normal on a crit, and (critChance ÷ 100) weights that bonus by how often it occurs. This gives the statistically expected damage averaged over many hits, which is the figure that matters for comparing builds and theory-crafting in games like Diablo, Path of Exile, or any RPG with crit mechanics.
How to use
Suppose your character deals 500 base damage, has a 35% crit chance, and a 2.5× crit multiplier. Enter 500 as Base Damage, 35 as Crit Chance, and 2.5 as Crit Multiplier. The calculator computes: effectiveDamage = 500 × (1 + (35 ÷ 100) × (2.5 − 1)) = 500 × (1 + 0.35 × 1.5) = 500 × (1 + 0.525) = 500 × 1.525 = 762.5 damage per hit on average. This means your crit stats are increasing your average hit damage by 52.5% above your base figure.
Frequently asked questions
How does increasing crit chance versus crit multiplier affect my average damage output?
Both stats multiply your effective damage, but their relative value depends on your current totals. Early in a build when crit chance is low, each percentage point of crit chance provides a larger proportional gain. Once crit chance is high (above 70–80%), investing in crit multiplier typically gives a better return because you are already critting most of the time. The formula shows that both scale multiplicatively, so the optimal balance requires running the numbers at your specific values rather than following a general rule.
What does a crit multiplier of 2x mean and how is it applied to damage?
A crit multiplier of 2.0x means a critical hit deals exactly twice your base damage. In the formula, this contributes a bonus of (2.0 − 1) = 1.0 times your base damage per crit, which is then weighted by your crit chance. Some games use a different convention where crit multiplier is expressed as the bonus damage only (e.g., '+100% damage') rather than the total multiplier, so always confirm which system your game uses before entering values. Using the wrong convention will produce an inflated or deflated result.
Why should I calculate effective damage instead of just looking at my base damage stat?
Base damage only tells you what happens on a normal, non-critical hit, which may be a minority of your actual hits if crit chance is high. Effective damage gives you the statistically expected average damage per hit, which is the true metric for comparing two builds or two pieces of gear. For example, a weapon with 400 base damage and 50% crit chance at 2× multiplier has an effective damage of 600, which beats a weapon with 550 base damage and no crit. Without the formula, the 550-damage weapon looks better when it is actually worse.