CalculatorCast
Math Finance Health & Fitness Date & Time Unit Converters Computer Physics Chemistry Construction Engineering Statistics Education Everyday Life Biology Automotive Cooking & Food Sports & Fitness Real Estate Photography Electrical Agriculture Travel Business
All Calculators Favorites ()
English Español Français Deutsch Português Italiano Nederlands Polski Türkçe 日本語 한국어 Svenska Norsk Dansk Suomi עברית

Punnett Square Calculator

Classic Punnett square cross for a single gene.

Introduction

Punnett Square Calculator — Classic Punnett square cross for a single gene. Enter Parent 1 genotype, Parent 2 genotype to get an instant, accurate result.

Formula

Builds a 2×2 monohybrid Punnett square by pairing each of parent 1's two alleles with each of parent 2's two alleles (4 combinations total), producing the offspring genotypes and their ratios — e.g. Aa × Aa gives 1 AA : 2 Aa : 1 aa.

Step-by-step

  1. Enter the Parent 1 genotype.
  2. Enter the Parent 2 genotype.
  3. Click Calculate to see your result instantly.

Real-world example

Example: With Parent 1 genotype = Aa, Parent 2 genotype = Aa, the Punnett Square Calculator gives Genotypes: AA, Aa, Aa, aa, Ratios: 1, 2, 1.

Frequently Asked Questions

How is dominance shown in the offspring genotype?
The dominant (uppercase) allele is conventionally listed first in each offspring genotype, e.g. "Aa" rather than "aA", though both represent the same heterozygous genotype.
What does the classic 3:1 ratio mean?
Crossing two heterozygotes (Aa × Aa) produces genotypes in a 1 AA : 2 Aa : 1 aa ratio, which translates to a 3:1 dominant-to-recessive phenotype ratio if A is fully dominant.
What inputs does the Punnett Square Calculator need?
You'll need to provide: Parent 1 genotype, Parent 2 genotype. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Punnett Square Calculator?
The Punnett Square Calculator applies the formula exactly as calculated — Builds a 2×2 monohybrid Punnett square by pairing each of parent 1's two alleles with each of parent 2's two alleles (4 combinations total), producing the offspring genotypes and their ratios — e.g. Aa × Aa gives 1 AA : 2 Aa : 1 aa. — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Punnett Square Calculator free to use?
Yes, the Punnett Square Calculator is completely free, requires no signup, and runs instantly in your browser.

About the Punnett Square Calculator

The Punnett Square Calculator uses a real, verifiable formula — Builds a 2×2 monohybrid Punnett square by pairing each of parent 1's two alleles with each of parent 2's two alleles (4 combinations total), producing the offspring genotypes and their ratios — e.g. Aa × Aa gives 1 AA : 2 Aa : 1 aa. — so results are accurate every time, not an approximation.