Gaming calculator
Drop Chance Calculator
See how repeated attempts change the chance of receiving at least one drop.
Assumes independent attempts with the same drop chance each time.
Chance of at least one drop
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How it works
The formula assumes every attempt is independent and uses the same probability. Pity systems and changing rates require a different model.
P(at least one) = 1 − (1 − p)ⁿ
Worked example
A 5% drop chance across 20 attempts gives about a 64.15% chance of at least one drop.
How to use this tool
- Enter the known values and choose units where available.
- Check the primary result and supporting details.
- Clear or replace an input to calculate another case.
Frequently asked questions
What happens with invalid or incomplete inputs?
The result remains blank until the required inputs form a finite, meaningful calculation. Zero denominators and physically impossible negative quantities are not calculated.
Can I use decimal values?
Yes. The tool accepts decimals and keeps full precision for the calculation while rounding the displayed result for readability.