Predicting trait inheritance is a critical step in any selective breeding project. Whether you are isolating a single mutation or mapping out complex, multi-generational crosses for specific fin shapes and/or color patterns, this Punnett Square Generator helps with predicting population genetics. Designed to dynamically handle up to four genes simultaneously, this tool makes it easy to visualize offspring probabilities quickly. It doesn’t replace standard tools for the most complicated breeding programs that include sex linkages or other correlations. But does a good job to help back of the envelope type calculations. NOTE: This application doesn’t currently support mobile use.

How to use the generator:

1. Select the number of genes: Choose between 1 and 4 genes to track from the dropdown menu.

2. Define your alleles: Assign your dominant and recessive letters (for example, tracking a recessive mutation like the blond base body color (b) alongside recessive European Blau (r) genetics).

3. Input parent genotypes: Enter the exact genetic makeup for your male (top) and female (left) breeders.

   • Example for base body color and European Blau could look like so:

     • Male: BbRr

     • Female: Bbrr

4. Generate & Analyze: Click 'Generate Punnett Square' to build the matrix. You can use the interactive highlighter tool to click and color-code specific squares, which instantly calculates the exact percentage of offspring carrying your target phenotypes.