Drop rate calculator

Find your real chance of getting that rare drop — and how many tries it takes for a 50%, 90% or 99% chance.

Free, no sign-up

Before you use it

Works well for

  • Chance of getting a rare drop in N tries
  • Gacha and loot box odds, including pity
  • Tuning drop rates in game design

Not the right tool for

  • Drops whose chance changes after each try (other than a hard pity)
  • Predicting your personal luck — it shows probabilities, not outcomes

Why a 1% drop isn't guaranteed in 100 tries

Each try is independent, so the chance of getting at least one drop in n tries is 1 − (1 − p)n. For a 1% drop, 100 tries gives about 63%, not 100%. You need 69 tries for a coin-flip chance, 230 for 90% and 459 for 99%.

Pity systems

Many games guarantee the item after a fixed number of tries. Enter that number and the calculator includes it: the chance jumps to 100% at the pity limit, and the average number of tries falls.

For game designers

Use it to tune drop rates: pick how many tries feels fair for most players, look at what the unlucky 10% will experience, and decide whether you need a pity limit to protect them.

Frequently asked questions

Does bad luck make the next drop more likely?

Not unless the game says so. Without pity, every try has the same chance — this is the gambler's fallacy.

What does "copies you want" do?

It calculates the chance of getting at least that many drops, using the binomial distribution.

Is the math exact?

Yes. The formulas are exact, and they were checked against simulations of millions of tries.