What formula is used for "at least one crit"?

The complement rule: P(at least 1) = 1 - (1 - p)^N, where p is the per-hit crit probability and N is the number of attacks. This is exact, not an approximation.

How is expected crits calculated?

Expected crits = N × p. For example, 10 attacks at 25% crit rate yields an expected value of 2.5 crits. This is the long-run average over many sessions.

Does this account for crit damage multipliers?

No — this tool calculates crit hit probability only. Multiply your expected crits by your crit damage multiplier separately to estimate expected bonus damage.

My game uses pseudo-random distribution (PRD). Is this accurate?

No. PRD (used in Dota 2 and some other games) artificially reduces early-hit streaks and catches up over time. The results here assume true independent random rolls per attack.

What is a good crit rate to aim for?

At 25% crit rate over 10 attacks, you have about a 94% chance of landing at least one crit. At 50% over 5 attacks, that rises to ~97%. The right target depends on your rotation length and build synergies.

Crit Chance Calculator

Name: Crit Chance Calculator
Availability: InStock
Author: Nham Vu

Enter your crit rate and number of attacks to instantly see the probability of landing at least one crit and the expected number of crits.

Crit Chance Parameters

Critical Hit Rate (%)

Enter a value between 0.01 and 100

Number of Attacks

How many hits in your rotation (1 – 10,000)

Quick Presets

Results

At Least 1 Crit

—

probability

Expected Crits

—

average per rotation

Zero Crits Chance

—

probability of no crits

Expected Crit DMG

—

% of attacks are crits

At Least 1 Crit — Visual

—

0% 50% 100%

Cumulative Crit Distribution

Crits	Exact Prob.	At Least N Crits
Enter values above to see breakdown

Summary

Enter your crit rate and number of attacks to instantly see the probability of landing at least one crit and the expected number of crits.

How it works

Enter your base critical hit rate as a percentage (e.g. 25 for 25%).
Enter the number of attacks you plan to make in a burst or rotation.
The calculator applies the formula P(at least 1 crit) = 1 - (1 - p)^N.
Expected crits is calculated as N * p.
Results update instantly — no submit button needed.
Use the breakdown table to see cumulative crit probabilities for 1, 2, 3 or more crits.

Use cases

Evaluating whether increasing crit rate is worthwhile for your build.
Comparing two weapons with different crit stats in RPGs like Genshin Impact or Path of Exile.
Estimating burst damage reliability over a skill rotation in MMORPGs.
Planning ability cooldowns around expected crit windows.
Understanding crit variance in card games or tabletop RPGs.
Teaching probability concepts with an intuitive gaming context.

Frequently Asked Questions

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Last updated: 2026-05-29 · Reviewed by Nham Vu