Crested Gecko morph calculator
Choose the genes each parent carries and see the full clutch odds — per gene and per combination. Covers 4 curated crested gecko genes, with the allelic, lethal and sex-linked cases handled properly.
Sire (male)
Which genes the father carries, and in what form.
No genes yet — this parent is treated as a normal animal.
Dam (female)
Which genes the mother carries. Sex matters only for sex-linked genes.
No genes yet — this parent is treated as a normal animal.
Add at least one gene to a parent to see the predicted offspring.
What to watch for in crested gecko pairings
Lilly White is the one every crested keeper needs to know: it is dominant, and two copies are not viable. Lilly White bred to Lilly White loses roughly a quarter of the clutch before hatching, and the surviving animals come out two-thirds Lilly White rather than the three-quarters a naive calculation gives. HerpSync models the lethal class and renormalises the survivors, so the odds it shows are the odds you will actually see in the incubator.
- Lilly White — lethal with two copies, so a quarter of the clutch never hatches and the surviving odds are renormalised.
- 13 polygenic traits are excluded from the picker entirely, because no honest percentage can be given for a line-bred trait.
Go deeper
The species page lists every curated crested gecko gene with its mode of inheritance, super form and flags, alongside breeding and incubation notes.
Common questions
Is the crested gecko morph calculator free?
Yes. No account, no sign-up, and no limit on how many pairings you try. Everything runs in your browser and nothing is stored.
What happens if I breed two Lilly White crested geckos?
Lilly White is homozygous-lethal. Around a quarter of the embryos inherit two copies and do not survive, so among the hatchlings you see roughly two-thirds are Lilly White and one-third are not. Many breeders avoid the pairing entirely for that reason.
Why can't the calculator predict a Harlequin?
Harlequin is polygenic — a pattern trait produced by many genes together and strengthened by selective breeding. There is no single gene to pass on, so no honest percentage can be given. HerpSync records it against the animal and tracks it down the line instead of inventing odds.
Run this against your own crested geckos
Record genotypes on each animal and every prediction comes from real records — with pedigrees, inbreeding coefficients and what each clutch actually produced.
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