Punnett Square Calculator

1. Define Parental Gametes

Click the '+' to add gametes. The number of traits will be detected automatically from the length of your gametes (e.g., 'Ab' is 2 traits).

How to Use the Visual Punnett Square Calculator

This tool offers a dynamic and interactive way to perform genetic crosses. Instead of typing full genotypes, you directly input the possible gametes from each parent.

  1. Input Gametes: Click into the dashed boxes at the top and left to type the gametes for Parent 1 (top) and Parent 2 (left). Use the + button to add more possible gametes for each parent. For example, for a parent with genotype 'Aa', the gametes would be 'A' and 'a'. For 'AaBb', the gametes would be 'AB', 'Ab', 'aB', and 'ab'.
  2. Define Traits: As soon as you type a gamete, a new section will appear below for you to define what each trait represents. The tool automatically detects the number of traits based on the length of your gamete (e.g., 'ab' = 2 traits).
  3. Set Dominance Rules: For each trait, specify the phenotype for the dominant and recessive alleles. You can also select "Incomplete Dominance" or "Codominance" to define a unique phenotype for the heterozygous state.
  4. Calculate: Once all gametes and traits are defined, click the "Calculate & Fill Square" button.
  5. Analyze Results: The tool will generate the completed Punnett square, along with detailed tables and charts for both genotype and phenotype ratios and percentages.

Understanding the Concepts

What is a Punnett Square?

A Punnett square is a diagram used by biologists to determine the probability of an offspring having a particular genotype. It illustrates how parental alleles might combine during fertilization. The square is named after Reginald C. Punnett, who devised the approach in the early 20th century.

Key Terms

  • Allele: One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome. Represented by letters (e.g., A, a).
  • Genotype: The genetic makeup of an organism, represented by the combination of alleles (e.g., AA, Aa, aa).
  • Phenotype: The set of observable physical characteristics of an individual resulting from the interaction of its genotype with the environment (e.g., tall, short, red flowers).
  • Gamete: A mature reproductive cell (like a sperm or egg) that unites with another to form a new organism. It contains half the genetic material of the parent.
  • Dominance: A relationship between alleles of one gene.
    • Complete Dominance: The dominant allele completely masks the effect of the recessive allele in heterozygous conditions.
    • Incomplete Dominance: The heterozygous phenotype is an intermediate blend between the two homozygous phenotypes (e.g., red and white flowers producing pink offspring).
    • Codominance: Both alleles are simultaneously expressed in the heterozygous phenotype (e.g., a flower with both red and white patches).