Gacha Probability Calculator
Enter a drop rate (%) and a number of pulls to see the chance of getting at least one. Add a pity cap (the pull where a drop is guaranteed) and the gem cost per pull, and you also get the expected pulls, the gems you need, and your odds with the gems you currently own. Everything runs in your browser, and nothing you type is sent to a server. For percentages and discounts, try the Consumption Tax & Discount Calculator.
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Notes
- Every pull is treated as independent with the same probability. Games with guaranteed slots, step-up banners, or changing rates will differ from the real odds.
- The pity cap is treated as "a drop is guaranteed on exactly that pull". Carry-over or reset rules after pity are not modeled.
- Probabilities are theoretical. A high chance is not a guarantee, so use the numbers to plan your spending and gem savings.
Glossary
Drop rate
The chance of getting the target character or item on a single pull. If a banner lists a combined rate such as "3% total for featured units", enter the rate for the one you are after.
Pity (spark)
A safety net that guarantees the target after a set number of pulls without it. With pity, both the pulls and the gems you need have a hard upper limit.
Expected pulls
The average number of pulls until the first drop. Without pity it is 1 divided by the drop rate; with pity it is lower because the run is cut off at the cap.
FAQ
Will 100 pulls at a 3% rate guarantee a drop?
No. The chance of at least one drop is 1 - 0.97^100, about 95.2%, so roughly 4.8% of players still get nothing. Only a pity cap guarantees a drop at that pull.
How do I enter a combined featured rate?
Enter the rate for the single unit you want. If two featured units share 1.5% and either is fine, use 1.5%; for one specific unit it is usually 0.75%. Rules differ per game, so check the official rates.
Am I sure to win if I pull the expected number of times?
The expected pulls is just an average. Without pity, your chance of having a drop by then is only about 63%. See "Pulls needed to reach a target chance" for the pulls to reach 50%, 90%, and 99%.
What does entering a pity cap change?
At the pity pull the chance becomes 100%, and the expected pulls and gems are capped there too. The gems to reach pity are shown as gems per pull times the pity count.
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