Gacha Pity Calculator Guide

What you enter

The pull rate is the chance per pull of the top tier or the featured one, as posted in the game's notice. The app doesn't fill it in. Rates differ by game and change, and a wrong one would be false.

If the game has pity, enter the pull where it's guaranteed. Leave it blank if not. If you've already built some up, enter that too.

Copies you want and pulls to do are required. Cost per pull is only for the expected cost.

How the chance is counted

With no pity and a rate p, the chance of none in n pulls is (1 - p) to the power n. The chance of at least one is 1 minus that.

Example: 10 pulls at 1%. 0.99 to the power 10 is about 90.4%, so at least one comes to about 9.6%.

The pulls to reach 50%, 90% and 99% are the first counts where the chance passes each level. At 1% that's 69, 230 and 459.

How pity changes it

With pity at h, the pull h after your last hit is a sure hit. Every hit resets the count to 0.

At 1% with pity at 100, the expected pulls are about 63.4, lower than the no-pity case. The worst case is the pity itself, 100 pulls. In the example above, 50% comes at 69 pulls and 90% and 99% both at 100.

If you've already built some up, it counts from what's left. If it's at or above the pity, it's set to just before the pity.

50/50 and multiple copies

With a 50/50, a top-tier pull may not be the featured one, and a miss guarantees the next one is. Enter the chance it's the featured one from the game's notice.

For example, with pity at 90 and a 50/50, the worst case for one featured copy is 90 plus 90, or 180 pulls.

With two or more copies, the count resets after each one and the math carries on.

This app never tells you to pull or not to pull. Odds are not a guarantee.

When it may not fit

Some games raise the rate in steps or have separate pity per tier. This app only counts a flat rate with a guaranteed hit at the pity.

If a number you enter is wrong, the result is wrong. Check the rate in the game's notice. Odds are not a guarantee.

Saving and sharing links

What you enter is saved in this browser only and never sent to a server. If browser storage is blocked, saving is skipped and the math still works.

Copy link puts your numbers in the address. Whoever opens it sees the same run. The address has no names, accounts or other personal data.