Drop Rate Calculator

The Drop Rate Calculator accurately computes the actual probability of obtaining an item from its drop rate in RPGs and online games. For example, an item with a 5% drop rate has a 1-(1-0.05)^10 ≈ 40.1% chance of being obtained within 10 attempts. The complement formula precisely calculates the 'probability of obtaining within N attempts' that is difficult to grasp from individual trial probabilities alone. Additionally, the tool features reverse calculation: the number of attempts needed for 50% probability (median), 90%, 95%, and 99% using the formula n = log(1-P) / log(1-p). The cumulative probability table shows gradual probability changes at a glance, useful for evaluating farming efficiency and setting psychological benchmarks.

If you want gacha odds, at-least-one-hit probability, or ceiling-aware attempts rather than a simple drop rate, use the [Gacha Probability Calculator](/en/calc/gacha-probability/). To estimate how many pulls it takes to complete every item, use the [Complete Gacha Calculator](/en/calc/complete-gacha/). For repeated success or failure streaks, use the [Consecutive Probability Calculator](/en/calc/consecutive-probability/) as well.