Model parental crosses with flexible dominance settings. Get simplified ratios, probabilities, and projected counts quickly. Visualize every phenotype outcome with neat tables and graphs.
Total offspring combinations = Number of Parent 1 gametes × Number of Parent 2 gametes
Phenotype probability = Phenotype count ÷ Total offspring combinations
Projected expected count = Phenotype probability × Chosen sample size
Simplified ratio = Divide all phenotype counts by their greatest common divisor
Chi-square = Σ ((Observed − Expected)² ÷ Expected)
For complete dominance, both homozygous dominant and heterozygous offspring share the dominant phenotype. Homozygous recessive offspring show the recessive phenotype.
For incomplete or co-dominance, each genotype class can produce a distinct phenotype, so one gene may create a 1:2:1 phenotype pattern instead of 3:1.
1. Select one, two, or three traits.
2. Enter a clear name for each trait.
3. Choose complete dominance or incomplete/co-dominance for every trait.
4. Enter both parent genotypes using only the shown allele letters.
5. Add a sample size if you want projected expected counts.
6. Optionally enter observed counts to compare real data.
7. Click the calculate button to see ratios above the form.
8. Use the graph, CSV, and PDF tools for reporting.
| Example | Parents | Model | Expected Phenotype Ratio | Notes |
|---|---|---|---|---|
| Seed color | Aa × Aa | Complete dominance | 3:1 | Classic monohybrid dominant versus recessive outcome. |
| Flower color | Aa × Aa | Incomplete / Co-dominance | 1:2:1 | Three phenotype classes can appear from one trait. |
| Seed color + shape | AaBb × AaBb | Complete dominance | 9:3:3:1 | Common dihybrid ratio with independent assortment. |
| Three traits | AaBbCc × AaBbCc | Complete dominance | 27:9:9:9:3:3:3:1 | Trihybrid cross with eight phenotype groups. |
A phenotype ratio shows how often visible trait outcomes are expected among offspring. It groups offspring by expressed characteristics rather than by exact genotype combinations.
Genotype ratio tracks allele combinations such as AA, Aa, and aa. Phenotype ratio combines genotypes that produce the same visible result under the selected inheritance model.
Yes. Choose the incomplete/co-dominance option for any trait. Heterozygous offspring will then be counted as a separate phenotype rather than being merged with the dominant class.
Each added trait multiplies the number of possible gamete and offspring combinations. More traits create more phenotype groupings, especially when traits use incomplete dominance.
Projected sample size scales calculated probabilities into expected counts for a chosen number of offspring, plants, or laboratory observations. It helps convert ratios into practical estimates.
Observed counts let you compare actual data with theoretical expectations. The calculator uses those values to compute a chi-square statistic for a quick goodness-of-fit check.
You can either enter observed counts in the same order as the results table or use exact labels followed by a number. Exact labels help avoid category mismatches.
It can speed up most ratio calculations and provide summaries, but Punnett squares remain useful for teaching, visual checking, and understanding how each allele combination forms.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.