Dihybrid Cross Calculator

Work out dihybrid cross instantly with clear inputs, formula shown and shareable results.

About Dihybrid Cross Calculator

Applies the classical dihybrid expectations for independently assorting genes, including the 9:3:3:1 self and 1:1:1:1 test cross ratios.

Formula

Dihybrid ratios

AaBb x AaBb gives 9:3:3:1 by phenotype; AaBb x aabb gives 1:1:1:1, which is why the test cross reveals gamete frequencies

Worked example

With the default values below, Dihybrid Cross Calculator returns Offspring showing both dominant traits of 56.25%. Change any input above and every figure here is recalculated in your browser.

Inputs used

Crossone of AaBb x AaBb (dihybrid self), AaBb x aabb (test cross), AaBb x AABB: AaBb x AaBb (dihybrid self)
Offspring expectedaccepts 1–100,000: 320

Results

Offspring showing both dominant traits: 56.25%
Offspring showing both recessive traits: 6.25%
Expected phenotype ratio: 9 : 3 : 3 : 1
Expected offspring with both dominant traits: 180.00

Step by step

1Values used
2Dihybrid ratios
3Offspring showing both dominant traits= 56.25
4Offspring showing both recessive traits= 6.25
5Expected phenotype ratio= 9 : 3 : 3 : 1
6Expected offspring with both dominant traits= 180.00

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

What breaks the 9:3:3:1 ratio?

Linkage, epistasis, lethal genotypes and gene interaction all distort it.

Why is the test cross useful?

Its phenotype ratio equals the gamete ratio of the heterozygous parent, so it measures recombination directly.