Loot probability.
Turn reward weights into chances you can reason about.
Reward pool
Weights are relative; they do not need to add up to 100.
| Target | Reward | Weight | Per roll |
|---|
Across multiple attempts
Select one or more target rewards in the pool.
How many attempts?
How the calculation works
Each outcome’s probability is its weight divided by the total weight. For several selected targets, their weights are added: success means receiving any one of them, not collecting all of them.
For per-roll probability p and n attempts, the chance of at least one success is 1 − (1 − p)ⁿ. Expected successes are n × p. The average wait for the first success is 1 ÷ p; this is an average, not a guarantee.
Zero-weight outcomes cannot drop. All-zero pools are invalid. The calculator does not model pity systems, changing weights, rolls without replacement, or multiple rewards per roll. A chance below 100% never becomes a guarantee in a finite number of attempts.
Your pool saves in this browser. The initial rewards are example data, not your game’s actual loot table.