Attempts for a Given Chance Calculator
Works backwards from the chance you want to the attempts it takes.
Attempts needed
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Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
Chance at that many attempts — %
Average attempts per drop —
Other chances
Reading this —
The formula
attempts = ln(1 − chance) ÷ ln(1 − rate), rounded up
Each extra attempt adds less, because the chance only ever approaches 100%.
What to watch out for
These are chances, not promises: at 90%, one player in ten still has nothing after that many attempts.
Frequently Asked Questions
How many tries for 90% at a 1% drop rate?
230 attempts.
How many for a coin-flip chance at 1%?
69 attempts.