Ball Python morph calculator
Choose the genes each parent carries and see the full clutch odds — per gene and per combination. Covers 49 curated ball python 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 ball python pairings
Ball pythons are where the simple textbook model breaks down, in four separate ways at once, and all four are modelled here: allelic complexes where two named morphs sit at the same locus and can never be inherited independently, super forms that are lethal, a gene whose inheritance depends on the offspring's sex, and compound hets that look like a morph rather than a carrier.
- Toffee and Candy; Lesser and Butter; Cinnamon and Black Pastel and Mocha; Phantom and Mystic — allelic, so they share a locus and cannot be inherited independently or stacked as separate supers.
- Spider and Champagne — lethal with two copies, so a quarter of the clutch never hatches and the surviving odds are renormalised.
- Banana — sex-linked, so results split into sons and daughters and it matters which parent carries it.
Go deeper
The species page lists every curated ball python gene with its mode of inheritance, super form and flags, alongside breeding and incubation notes.
Common questions
Is the ball python 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 is the difference between a ball python morph and a gene?
A gene is a single inherited mutation, like Pastel or Clown. A morph name sold at an expo is usually a combination of several genes — a Bumblebee is Pastel plus Spider. Only the genes are inherited; the combination name is just what breeders call that particular set.
Why can't I breed a Super Spider?
Spider is lethal in its homozygous form — an embryo that inherits two copies is not viable. Spider bred to Spider therefore produces roughly two-thirds Spider and one-third normal among the animals that hatch, not the 25/50/25 a Punnett square predicts. Champagne behaves the same way.
Why does Banana produce mostly males from some pairings?
Banana is sex-linked. Depending on which parent carries it, a pairing can throw predominantly male or predominantly female Bananas — the well-known male-maker and female-maker lines. A calculator that treats it as an ordinary co-dominant gene gets the sex ratio wrong.
Run this against your own ball pythons
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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