Loot Drop Chance Calculator

Summary

Enter a drop rate and number of attempts to instantly see your cumulative probability of getting at least one drop.

How it works

1. Enter the per-attempt drop rate as a percentage (e.g., 1 for 1%).
2. Enter the number of attempts — kills, dungeon runs, spins, or chests opened.
3. The calculator applies P = 1 − (1 − p)^n to find the cumulative probability.
4. The result shows the chance of getting at least one drop, plus the expected attempts needed for 50% and 90% confidence.
5. A probability curve chart updates in real time so you can see how odds improve with more attempts.

Use cases

• Estimate how many boss kills are needed to obtain a rare weapon.
• Plan farming sessions in MMORPGs and ARPGs before spending time grinding.
• Calculate dungeon run counts needed for a specific drop in games like World of Warcraft or Path of Exile.
• Understand gacha pull probabilities across multiple rolls.
• Compare the efficiency of different farming spots with different drop rates.
• Determine when it becomes statistically likely (>50% or >90%) that a drop has occurred.
• Settle debates with friends about how unlucky or lucky a farming session was.

Frequently Asked Questions