How to use (3 steps)
- Select an example or enter genotypes for Parent 1 and Parent 2.
- Choose 1 gene (2×2) or 2 genes (4×4).
- The Punnett square and ratios appear. You can copy a Markdown table or export CSV/LaTeX.
Two-gene mode assumes independent assortment. Phenotype ratios are guides assuming complete dominance.
Inputs (parent genotypes)
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Display options
Assumptions (independent assortment & complete dominance)
Two-gene mode assumes independent assortment. Phenotype ratios are guides based on complete dominance.
Results (Punnett square)
Selecting a cell highlights it in the summary.
How it’s calculated
- Generate parental gametes and combine them in a grid.
- Count occurrences to compute genotype proportions (%/ratio).
- Phenotype ratios are shown as guides assuming complete dominance and independent assortment.
This is a basic learning tool. Phase 1 does not handle linkage or special inheritance patterns.
When to use a Punnett square
Use this page before you have observed counts and want to predict the genotype or phenotype ratios that a planned cross should produce. It is most useful for classroom genetics, quick cross design checks, and explaining why a ratio such as 3:1 or 9:3:3:1 appears in the first place.
Best sequence
- Enter parent genotypes in one-gene or two-gene mode.
- Check the gametes and the grid to confirm the cross setup is what you intended.
- Review genotype ratios first, then phenotype ratios if complete dominance is a reasonable guide.
- If you later collect offspring counts, move to Mendelian chi-square to test fit.
How this genetics page differs from the others
- Punnett square predicts the ratio you expect before you collect offspring counts.
- Mendelian chi-square takes over once you want to test observed counts against that expected ratio.
- Hardy-Weinberg is for population equilibrium, where expected frequencies come from p and q.
- Wright-Fisher is for allele-frequency change across generations, not a single classroom cross.
FAQ
Does 9:3:3:1 always appear?
It is a classic case for AaBb parents with independent assortment and complete dominance. Different conditions yield different ratios.
Can I input Aa or aA?
Either is fine. The display is normalized to Aa.
Does it handle linkage or recombination?
Not in Phase 1 (independent assortment is assumed).
I want to paste the table into a report.
You can copy it as a Markdown table and paste directly (CSV/LaTeX also available).
When should I switch to Mendelian chi-square?
Switch once you have observed offspring counts and want to test whether the data still fit the expected ratio from the cross.
What this page does not cover
This is a simple inheritance teaching tool. It does not model linkage, recombination frequency, penetrance, or population drift. Use the output as a clean expected-ratio reference, then move to a family-specific follow-up tool when your question changes.
Related tools
- Mendelian ratio chi-square test calculatorTest whether observed offspring counts still fit the ratio predicted by your Punnett square.
- Hardy-Weinberg equilibrium calculatorMove from a single planned cross to population-level genotype expectations based on allele frequencies.
- Genetic drift simulator (Wright-Fisher)Explore how allele frequencies can drift over generations once you leave the single-cross classroom model.
Comments
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