What this calculator does
Multi-gene cross probability works out probability of a given number of recessive traits among offspring of a multi-gene cross. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
The inputs explained
| Field | What to enter |
|---|---|
| Heterozygous gene pairs (Aa × Aa) | A number. Starts at 2. |
| Number showing recessive phenotype | A number. Starts at 1. |
| Offspring to project onto | A number. Starts at 16. |
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the answer changes with heterozygous gene pairs (aa × aa)
Every other input is held at the calculator’s starting values while heterozygous gene pairs (aa × aa) varies. Select any row to load that scenario into the calculator.