ARK Breeding Calculator
ARK rolls each stat independently: the baby takes the higher parent value with 55% probability, the lower with 45%. Enter your pair below to see the chance of the perfect combination - and how mutations stack the odds.
Baby odds
| Stat | Mother | Father | Baby target ≥ | Chance |
|---|
Baby wild level shown assumes no mutation: 1 + inherited points per stat.
Reading the odds
The documented inheritance & mutation model
When an egg hatches, ARK builds the baby stat-by-stat: for each of the six stats it compares both parents and gives the baby the higher value with 55% probability (45% the lower; certain when equal). Wild points and mutation points inherit together - the baby's wild level is 1 plus the points it took.
After inheritance, up to three mutation rolls happen. Each roll first picks a random parent; if that parent's combined mutation counter is 20 or higher the roll dies (the 20/20 rule), otherwise it succeeds with 2.5%. A success adds +2 wild levels to one of the six mutable stats and rerolls one color region - speed can never mutate. With both parents clean, at least one mutation lands with 1 − 0.975³ = 7.31% probability; with one parent blocked it roughly halves to ≈ 3.7%; with both blocked it is zero.
A fresh mutation is only useful if the baby then keeps the mutated stat - the same 55% inheritance bias - so a mutation landing on your single tracked stat survives at 7.31% × (1/6) × 0.55 ≈ 0.67%, or about 1 in 150 eggs. This is exactly the "useful mutation" figure above.
Stacking works because counters gate new mutations, not inheritance: breed clean-counter females to a high-counter male and his mutated stats keep passing at full 55/45 odds while the mother's side stays eligible for new rolls. This is the backbone of every serious mutation line.
Breeding FAQ
How do mutations work in ARK?
Each baby gets 3 independent mutation rolls at 2.5% each (7.31% chance of at least one when both parents' counters are under 20). A successful mutation adds +2 wild levels to one of the six mutable stats (Health, Stamina, Oxygen, Food, Weight, Melee) and rerolls a color region. The 20/20 rule blocks new mutations from a parent whose combined matrilineal + patrilineal counter is at 20 or higher - but its stats still pass on, which is how mutation stacking works: keep breeding clean females to a mutated male.
What are the odds the baby keeps the better stat?
55%. For every stat the baby independently picks one parent's value with a 55% bias toward the higher one (45% the lower; 100% when equal). That bias is also why a fresh stat mutation is only kept ~55% of the time - the mutated stat competes in the same inheritance roll.
How many eggs until I get my perfect baby?
Multiply the per-stat odds: a baby needing 4 different stats from the stronger parent lands at 0.55^4 ≈ 9.2% - about 11 eggs on average. Add a new mutation to a specific stat on top (7.31% × 1/6 × 55% ≈ 0.67% per stat) and you are looking at roughly 1 in 150 eggs. The calculator below combines all of this for your exact pair.
Do levels above 20 mutations still count?
The counters track ancestry totals on each side and only gate NEW mutations at 20. The stat levels themselves are unaffected - creatures with hundreds of mutation levels still pass them at the same 55/45 odds. Counters can even overflow to negative values (signed 32-bit) which still counts as "under 20" for eligibility.