How to use this calculator
Choose your per-attempt success rate and your target probability. The answer rounds up to a whole attempt because a fraction of an attempt cannot meet the target. Without a guarantee, a rate below 100% can never reach mathematical certainty in a finite number of attempts. A high confidence target is a planning measure, not a spending recommendation.
The formula
ceil(log(1 − c) / log(1 − p))
Here p is a probability from 0 to 1, n is a whole number of attempts, C(a,b) counts combinations, and ∏ means multiply all the factors. The input labels define the other symbols.
A worked example
At 1% per attempt you need 299 attempts to reach at least a 95% chance.
Does this predict what I will get?
No. It describes a probability under the rules you enter. A single run can differ from the average. A displayed rounded 100% may still be slightly below certainty unless the model includes a guarantee.
Where do the rates come from?
You enter them. Check the rules and rate disclosure for your exact outcome. We do not supply odds for real products, collect account details or fetch rates from a game or seller.