LOOT & ECONOMY
Drop Rate Calculator
See at-least-one-drop odds, expected drops, and the attempts needed to reach 50%, 90%, or 99% chance.
PROBABILITY MATH
Calculate drop odds
Minimum whole attempts for at least one drop at each chance, assuming the same independent rate every time. No pity or soft-pity system is modeled.
1 − (1 − p)ⁿ — the probability of seeing at least one drop in n attempts.
Drop rate guide
This calculator shows the chance of at least one drop, expected drops, and the minimum attempts to reach 50%, 90%, or 99% odds at a fixed per-attempt rate. All calculations run locally in your browser.
Chance of at least one drop
With a fixed, independent chance p on each attempt, the chance of one or more drops in n attempts is 1 − (1 − p)ⁿ. At a 5% rate and 20 attempts, that is 64.2%; it is not a guarantee.
Expected drops = n × p. This is a long-run average, not a promise about any one player’s result.
How many attempts for a target chance?
The minimum whole number of attempts for a target chance c is ceil(log(1 − c) ÷ log(1 − p)). At 5%, 14 attempts reaches at least 50%, 45 reaches at least 90%, and 90 reaches at least 99%.
These estimates assume every attempt has the same independent drop chance. A guarantee, rising rate, or pity counter changes the model and should be calculated from that game’s exact rules.
Tip: Use a higher confidence target when planning a budget, but remember that even 99% is not a guarantee.
Frequently asked questions
Does a 5% drop rate mean I get it in 20 tries?
No. At a constant 5% chance per independent attempt, 20 tries gives about a 64.2% chance of at least one drop and about a 35.8% chance of none.
How many attempts are needed for a 90% chance?
At a constant 5% drop rate, 45 attempts are the minimum for at least a 90% chance of one or more drops. The calculator updates this threshold for the selected rate.
Does this calculator include pity or soft pity?
No. It assumes an independent attempt with a fixed drop rate. A guaranteed drop, increasing rate, or game-specific pity reset needs a calculation based on those exact rules.
What does expected drops mean?
Expected drops = attempts × drop rate. At 5% over 100 attempts the expected count is 5, but this is an average across many runs, not a guaranteed result in one run.
Privacy note: drop-rate calculations happen in your browser. Nothing is uploaded.