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Returns the at-least-once chance, the pulls needed for a target percent, and the expected pulls to land one, from any rate between 0.001 and 100 percent.

📘 How to Use

  1. Enter the drop rate as a percent
  2. Enter the number of pulls and your target probability
  3. Read the at-least-once chance, pulls for target, and expected pulls

Gacha Pull Probability Calculator

Chance of at least one pull
— %

—

Pulls needed for target
— pulls
Expected pulls (mean)
— pulls

Theoretical average pulls required to obtain one drop

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※ Formula for at-least-once chance: 1 - (1 - p)^N (p = drop rate, N = pulls)

※ Each pull is treated as an independent event. Pity and guaranteed drops are not modeled

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Gacha Pull Probability Calculator | Real Odds From Any Drop Rate

Get three numbers at once from a drop rate and pull count: the chance of at least one pull, the pulls needed for a target percent, and the expected pulls to land one. Handles rates from 0.001% to 100%.

💡 About this tool

A 1% banner over 100 pulls feels like a sure thing, but the real number is 63.4% — better than one in three players walks away empty-handed. Every pull is an independent trial, so stacking pulls never drives the "all misses" chance to zero. This calculator does the math players consistently get wrong.

It works from the complement rule: the chance of zero hits is (1 − rate)^pulls, and one minus that gives the chance of at least one. It also inverts the formula to answer "how many pulls for a 90% chance?" and reports the expected pulls to obtain one copy (1 / rate). Use it to budget before a rate-up banner, sanity-check whether to keep pulling toward pity, or size a multi before you spend.

🧐 Frequently Asked Questions

If the rate is 1%, do 100 pulls guarantee a hit? No. The chance of at least one hit is about 63.4%. The remaining 36.6% miss entirely, so 100 pulls is not 100%.

What should I set as my target probability? 50% is the median — a coin-flip outcome — while 90% is a practical safety line. If you want comfort, check the pull count needed for 90% to 95%.

Does this account for pity or guaranteed drops? No. It treats each pull as an independent event with a fixed rate. If your game has a pity ceiling, your real odds are better than this baseline model.

What does expected pulls mean? It is the theoretical average pulls to land one copy, equal to 1 / rate. At a 1% rate that is 100 pulls on average — a long-run mean, not a promise that pull 100 succeeds.

📚 Why 100 Pulls at 1% Isn't a Lock

Many modern gacha titles set a base rate near 0.6% to 1% but layer on a pity ceiling that guarantees a rare after a set count, plus a soft-pity zone where rates spike past a threshold. That is why the base rate alone reads scarier than the experience feels. When you read a banner's odds, look at both the published base rate and the safety net behind it — the baseline math here is the floor, and pity only moves your real odds upward.