How to use the punnett square calculator
Prepare the values for this calculation
Calculate monohybrid offspring genotype probabilities from two diploid parent genotypes using alleles A/a. Use the formula below to check that it answers your question. Read the input units before transferring figures from a statement, measurement or dataset.
Enter and check each input
- Parent 1 genotype: choose AA, Aa, aa. Match this selection to the data you enter.
- Parent 2 genotype: choose AA, Aa, aa. Match this selection to the data you enter.
The input table gives a complete example. Keep units and time periods consistent across related fields.
Calculate and resolve any input error
Choose Calculate after entering the values. Changes also update the answer after a short pause. If an error appears, follow its message, correct the field and calculate again. Reset restores the example values.
Interpret the answer
Check Offspring genotype probabilities first. With the unchanged example inputs, it is AA 25%, Aa 50%, aa 25%. Interpret it using the formula and assumptions on this page.
Compare and keep a useful result
The result diagram shows the inputs, method and output. A numeric chart is shown only when the calculation supports a meaningful numeric relationship.
Use Copy result or Download CSV to keep the answer. Share tool shares the page address without placing your input values in the URL. Recheck inputs and assumptions before using the result for a decision.
Punnett Square Calculator formula
Each parent contributes one allele with equal probability; the four gamete combinations are counted.
Inputs and units
| Input | Format / range | Example |
|---|---|---|
| Parent 1 genotype | Select an option | Aa |
| Parent 2 genotype | Select an option | Aa |
Worked example
Using the example inputs above, the offspring genotype probabilities is AA 25%, Aa 50%, aa 25%.
- Offspring genotype probabilities
- AA 25%, Aa 50%, aa 25%
Results and assumptions
The output uses the offspring genotype probabilities convention and formula shown above. Match the entered units and source assumptions when comparing results.
Fix an input or unexpected result
If your answer differs from the example, choose Reset and compare every field, including selected units and options. Check percentage versus decimal entry and whether values describe the same period. Round only the final displayed answer when reproducing the formula.
If a discrepancy remains, report the calculator issue with the page address, non-sensitive example inputs, actual result, expected result and a reference for your calculation.