Mendel Punnett

Enter two alleles per locus: AA, Aa or aa. Uppercase and lowercase distinguish the two alleles; use the same gene symbols for both parents. For two loci, enter e.g. AaBb. Allele order and locus order are normalized: bBaA becomes AaBb.

Rows are gametes from parent 1 (P1), columns from parent 2 (P2). Their percentages are the gamete probabilities; a cell’s probability is the product of its row and column probabilities. Repeated offspring genotypes are combined in the distribution. CSV exports cell counts, total cells and exact probabilities.

The model assumes equal segregation, random fertilization and independent assortment of the two loci. Complete dominance is an optional additional assumption for phenotypes: A– means AA or Aa, aa is recessive. In a two-locus cross, A–B– means at least one uppercase allele at each locus. Turn off phenotypes if this assumption does not fit your example.

These are probabilities, not guaranteed counts in a small family. The classic Aa × Aa gives 1:2:1 genotypes and 3:1 phenotypes; AaBb × AaBb gives 9:3:3:1 phenotypes under the stated assumptions. No linkage, epistasis, multiple alleles, sex-linked inheritance or segregation distortion. Computation stays local without storage.