How many tries before one success
Enter the success rate p for a single try and a number of tries n, and the tool returns the cumulative chance of at least one success as 1 − (1 − p)^n. The expected number of tries until the first success is 1/p, and the tries needed to reach a target cumulative probability q is ln(1 − q) / ln(1 − p) rounded up. At a 3% rate, 30 tries give 59.8993% cumulative odds, the expected count is 33.33 tries, and passing 95% cumulative odds takes 99 tries.
Every try is assumed independent with the same probability. Rising rates after failures, protection items, and guaranteed successes after a fixed count are not modeled. A long streak of failures does not raise the chance on the next try.
This tool works from the formula only; it does not roll random draws to simulate hits and misses, and it does not calculate upgrade costs or material use. Treat it as study material for probability; written as of October 2026.
Frequently asked questions
It is 1 − 0.97^30 = 59.8993%. Even after all 30 tries, failure is still more than a 40% outcome.
No. The expected count 1/p is an average, and because every try is independent, past failures never raise the next chance.
No. This calculator only covers independent tries with the same probability every time.