Calculate perfect-IV breeding odds in Stardew Valley
Breeding for flawless stats is a numbers game: each offspring inherits some stats and rolls the rest. This calculator turns parent IVs and inheritance rules into the real probability of a perfect roll and the expected number of attempts, so you know what your breeding project will cost.
How it works
For a stat with maximum IV 31, the per-stat chance of being perfect is:
- Inherited stat: 1 if a parent’s IV in that stat is 31, otherwise 0.
- Random stat:
1 / 32, since values range 0 to 31 inclusive.
Because inheritance picks a fixed number of stats at random, the model blends these: each target stat’s perfect chance is a weighted mix of the inherited case and the random case. The chance an offspring is perfect across all your target stats is the product of their per-stat probabilities, and the expected attempts is the reciprocal:
attempts ≈ 1 / (p1 × p2 × ... × pk)Tips and example
If both parents have 31 in two target stats and inheritance passes 3 of 6 stats, those targets pass perfectly far more often than the random 1 in 32. Chasing four perfect random stats at once is brutal — (1/32)^4 is roughly 1 in a million — which is why breeders stack 31-IV parents to convert hard random rolls into guaranteed inherited ones.