Find the chance of getting at least X drops in N attempts.
Examples (gacha pulls):
Chance of at least drops
in attempts
Exactly
Expected drops
Chance by target count
Type the per-attempt drop chance as a percentage or 1-in-X.
Type the number of attempts and how many drops you want at least.
See the chance of reaching your target, plus the expected drop count.
When each attempt is independent, the number of drops follows a binomial distribution. This calculator sums the probability of every outcome from your target up to the maximum to give "at least X drops" — the number players actually care about.
Whether you need 5 copies of a character or 3 rare materials, asking "at least X" is the honest question. The binomial math handles it exactly, unlike the single-drop "at least 1" formula.
It sums the binomial probabilities of getting exactly X, X+1, …, up to the maximum possible drops. The formula is the standard binomial CDF.
The calculator also shows the probability of exactly the target count — for example exactly 3 copies in 100 pulls.
Yes. The drop rate calculator handles "at least one" for a single item. This one handles any target count, including multiple copies.
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