Calculadora de Quadrado de Punnett (Diíbrido)
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
AaBb × AaBb → 9 A_B_ : 3 A_bb : 3 aaB_ : 1 aabb
About this calculator
The Dihybrid Punnett Square Calculator is an educational tool that simulates the cross between two organisms heterozygous for two genes (AaBb × AaBb). It automatically generates all 16 possible genotypic combinations and calculates the expected phenotypic ratios, such as the classic 9:3:3:1 ratio. Ideal for genetics students who want to visualize Mendel's law of independent assortment.
How it works: simply enter the parental genotypes (default AaBb), and the calculator builds a 4x4 table with the possible gametes (AB, Ab, aB, ab) from each parent. It then combines each gamete to form offspring, counting how many show each dominant/recessive phenotype. The result displays probabilities for each genotype and phenotype, making dihybrid inheritance easier to understand.
Use this calculator in biology classes, exam preparation, or review of Mendelian concepts. It is particularly useful for quickly checking dihybrid crosses, avoiding manual errors. For example, when studying seed color and texture in peas, you can confirm the expected ratio of 9 yellow smooth, 3 yellow wrinkled, 3 green smooth, and 1 green wrinkled.
Caution: the tool assumes independent assortment and complete dominance. It does not apply to linked genes or gene interactions like epistasis. Also, the 9:3:3:1 ratio is expected only for crosses between double heterozygotes. For other parental genotypes, the proportions change. Always interpret results within the classical Mendelian model.
Frequently asked questions
What does the 9:3:3:1 ratio mean?
It indicates the expected phenotypic proportions in the dihybrid cross AaBb × AaBb: 9 offspring with both dominant phenotypes, 3 with dominant first and recessive second, 3 with recessive first and dominant second, and 1 with both recessive.
Can I use the calculator for other parental genotypes, like AABb × AaBB?
Yes, but the tool currently only offers the default AaBb × AaBb. For other crosses, the proportions will differ. You can modify the genotypes manually if the calculator allows custom input.
Does the calculator account for genetic linkage?
No. It assumes genes are on different chromosomes (independent assortment). For linked genes, phenotypic ratios deviate from 9:3:3:1.
How do I interpret the results as percentages?
Probabilities are given as fractions (e.g., 9/16) and can be converted to percentages (9/16 = 56.25%). The calculator shows both fraction and percentage if available.
What is the difference between genotype and phenotype in the results?
Genotype is the allele combination (e.g., AaBb), while phenotype is the observable trait (e.g., yellow smooth seed). The calculator displays both: the complete genotypic distribution and the phenotypic summary with the 9:3:3:1 ratio.