Find the real chance of getting that rare drop after N attempts.
Common examples:
Chance of at least one drop
in attempts
Expected drops
average over many attempts
Chance of zero drops
Attempts for certainty
Type the drop rate either as a percentage (e.g. 2%) or as 1-in-X (e.g. 1 in 50).
Type how many kills, chests or rolls you plan to do.
See the probability of at least one drop, expected drops, and attempts for 50/90/99% certainty.
A common mistake is assuming a 1% drop rate guarantees a drop in 100 attempts. In reality, after 100 attempts your chance of at least one drop is 1 − (0.99^100) ≈ 63%. After 200 it is about 87%, and only after roughly 459 attempts do you hit 99%.
The formula P = 1 − (1 − p)^n lets you plan exactly how long your grind will take. Use the certainty column to set realistic expectations and avoid burnout hunting that rare mount or weapon skin.
The probability of getting at least one drop in n attempts is 1 − (1 − p)^n, where p is the per-attempt drop chance. This calculator does it instantly.
Each attempt is independent. The chance of 100 straight failures is (0.99)^100 ≈ 37%, so the chance of at least one success is only about 63%.
Nothing is ever guaranteed, but to reach 99% certainty you need about 459 attempts, and 90% certainty takes about 230 attempts.
We use cookies to improve your experience and for analytics. By continuing, you agree to our use of cookies. Learn more
Play games offline & get instant access