Genetics Calculators
Genetics and heredity calculators model Mendelian phenotypic ratios, multi-locus recombination frequencies, and Hardy-Weinberg population equilibrium dynamics.
The genetics calculators answer two kinds of questions: what proportions a cross is expected to produce, and what a population's allele data implies. Punnett-based tools handle single and multi-trait crosses, while the allele frequency and Hardy-Weinberg calculators move from individual matings to population-level arithmetic. If you are working through an introductory course, start with the Punnett square calculator and let the dihybrid and trihybrid tools extend the same logic to more genes. Conversions such as DNA to mRNA and DNA copy number serve a different need: checking molecular arithmetic rather than predicting offspring.
Every prediction here assumes simple Mendelian inheritance with full penetrance. Real traits often involve codominance, incomplete dominance, or several genes acting at once, so treat an expected ratio as a starting point rather than a guarantee; the codominance calculator covers the cases where a straight dominant-recessive model breaks down. Hardy-Weinberg output assumes a population in equilibrium, with no selection, migration, or genetic drift, which makes departures from the expected frequencies the interesting result. Students use these tools to check course answers, and researchers reach for them as quick arithmetic checks before committing to deeper analysis.
Start here
Three picks, one per job: start with the one that matches what you came to calculate.
- Cross one trait, two parents: Punnett Square Calculator: the standard grid for a 3:1 or test-cross expectation
- Score a two-gene litter: Dihybrid Cross Calculator: sixteen cells plus expected counts for the batch you entered
- Work backwards from counts: Allele Frequency Calculator: turns raw tallies into p, q and carrier risk
Calculators
Mendelian crosses
Trait-specific crosses
Population genetics
Sequence and lab arithmetic
Guides & explainers
Each guide goes deep on the science behind one or two calculators and links straight into them.
- Tri-Allelic Inheritance & ABO Blood Groups Guide
- Genetic Linkage & Recombination Frequency Guide
- What Is a Punnett Square, and How Do You Read One?
- Dominant vs Recessive Traits: A Quick Reference
- Hardy-Weinberg Equilibrium Explained in Plain English
- Can Two Brown-Eyed Parents Have a Blue-Eyed Baby?
- Understanding Allele Frequency and Population Genetics
Which tool do I need?
| If you need to… | Use | Why this one |
|---|---|---|
| predict ratios for a single gene | Punnett Square Calculator | fastest grid, textbook 3:1 output |
| check two or three traits at once | Dihybrid Cross Calculator | independent assortment in one grid with expected counts |
| handle ABO blood types for an unborn child | Blood Type (Child) Calculator | models codominance and the Rh system together |
| test genotype counts against random mating | Hardy-Weinberg Equilibrium Calculator | expected numbers plus a chi-square comparison |
| convert nanograms of DNA into molecule counts | DNA Copy Number Calculator | length-aware moles, copies per microliter and nM |
| turn mutants out of a screen into a rate | Mutation Frequency Calculator | per-base, per-gene and per-genome units side by side |
Genetics: common questions
Which calculator fits a two-gene cross?
The dihybrid calculator expands both four-letter parent genotypes into sixteen cells and scales the 9:3:3:1 ratio to your progeny count. Drop to the Punnett page for one gene, or move up to the trihybrid page when a third locus is involved.
Can these pages handle codominance and blood types?
Yes. The codominance page works roan, snapdragon and ABO-style examples where the heterozygote keeps its own phenotype, and the blood type child calculator covers the full three-allele ABO system with Rh probabilities.
How do I move from one cross to a whole population?
Start with the allele frequency page to get p and q from your counts, then hand those frequencies to the Hardy-Weinberg page, which prints expected genotype counts and compares them with what you observed.
My counts do not match the expected ratio. What now?
Check the sample size first, since small litters scatter widely. Beyond that, look for linkage, epistasis or lethal genotypes in crosses, and for inbreeding or population structure when the Hardy-Weinberg test flags a deviation.
Where do DNA mass and sequence questions belong?
Use the copy number page to turn nanograms into molecules using fragment length, and the DNA to mRNA page to transcribe and translate a sequence. Both feed the same molecular arithmetic the mutation rate page relies on.
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