Gacha drop rate and pity calculator

From the drop rate, how many pulls until you get it?

Enter the drop rate (%). You get how many pulls it takes: the average, and the numbers within which 50%, 90% and 99% of people succeed. It also supports how many you want and a pity (guaranteed on the N-th pull).

Drop rate (%) Number you want Pity (guaranteed on pull N, optional) Price per pull (any currency, optional) Planned number of pulls (optional)

How it works

Without a pity, the number of pulls until the first success follows a geometric distribution with probability p; for k copies the average is k ÷ p. With a pity at N, the N-th pull is guaranteed and the count restarts after a hit. A drop rate of 3% does not mean “guaranteed within 33 pulls”: after 100 pulls about 5% of people still have nothing.

When this does not apply

• Use the published rate as it is. The calculator cannot know whether the published rate is accurate.
• It assumes each pull is independent. Games whose rate rises as you pull (soft pity) are not supported.
• Pity here means “guaranteed on pull N, then the count restarts.” Exchange systems and carry-over pity are not included.

To collect every type, use the completion calculator.