What this calculator does
Dihybrid cross ratios works out genotype and phenotype ratios from a cross of two heterozygous two-gene parents. 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
FormulaAaBb × AaBb over a 4×4 Punnett square gives the classic 9:3:3:1 phenotypic ratio when both traits show full dominance
The inputs explained
| Field | What to enter |
|---|---|
| Parents (both AaBb, standard dominant/recessive) | A list of numbers, separated by commas or spaces. |