Morph Outcome Probability Calculator

Q: How does recessive inheritance work in ball pythons?

Recessive traits require two copies of the gene to be visible. Breeding two het (heterozygous) animals gives 25% visual, 50% het, and 25% normal offspring. Breeding a visual to a het gives 50% visual and 50% het offspring.

Q: What is the difference between dominant and co-dominant morphs?

Dominant morphs show the trait with one copy of the gene, and the super (homozygous) form looks the same as the single-copy form. Co-dominant morphs show the trait with one copy but display a different "super" form when homozygous, like Spider vs Super Spider.

Q: Can I predict exact numbers of each morph in a clutch?

Probabilities predict the likelihood for each individual egg, not exact counts. A 25% probability means each egg has a 1-in-4 chance, but a clutch of 8 eggs will not always produce exactly 2 of that morph. Actual results vary from statistical expectations.

Q: What does "66% possible het" mean?

When breeding a het animal to a normal, each normal-appearing offspring has a 66% chance of carrying the recessive gene (being het). This is because we know 50% are het statistically, but we cannot visually distinguish them from normals, so each individual is labeled "66% pos het."

The Morph Outcome Probability Calculator uses Punnett square genetics logic to predict offspring outcomes from any reptile pairing. Select the sire and dam genetic traits including visual morphs and het status. The calculator shows all possible offspring outcomes with percentage probabilities for each combination, helping you plan pairings strategically.

Disclaimer: Genetic calculations assume standard Mendelian inheritance. Actual results may vary. Some morphs have complex or polygenic inheritance that this calculator does not model. Always research specific morph genetics before making breeding decisions.

Define the Pairing Genetics

Gene Name

Inheritance

Sire Status

Dam Status

Gene Name

Inheritance

Sire Status

Dam Status

Try it with your real data in HatchLedger

This tool is a preview. Get the full experience with saved records, alerts, and integrations inside HatchLedger.

How to use this tool

1Add each gene involved in the pairing using the "Add Gene" button.
2For each gene, select the inheritance mode (recessive, co-dominant, or dominant).
3Set the sire (male) status: none, het, or visual for each gene.
4Set the dam (female) status: none, het, or visual for each gene.
5Click "Calculate Probabilities" to see all possible offspring outcomes.

Frequently Asked Questions

How does recessive inheritance work in ball pythons?

What is the difference between dominant and co-dominant morphs?

Can I predict exact numbers of each morph in a clutch?

What does "66% possible het" mean?

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