Calculating Genotype Frequency from Allele Frequency Calculator

Enter allele frequencies and population size for estimates. See genotype ratios, counts, and checks together. Download clean tables for study, review, records, and sharing.

Calculator Form

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Example Data Table

Allele 1 Allele 2 p q F Population AA Aa aa
A a 0.6000 0.4000 0.0000 500 0.3600 0.4800 0.1600
B b 0.7000 0.3000 0.1000 800 0.5110 0.3780 0.1110

Formula Used

The standard two allele model uses these relationships:

  • p + q = 1
  • AA frequency = p2
  • Aa frequency = 2pq
  • aa frequency = q2

If you use an inbreeding coefficient F, the adjusted model becomes:

  • AA = p2 + Fpq
  • Aa = 2pq(1 - F)
  • aa = q2 + Fpq

Expected count for each genotype = genotype frequency × population size.

How to Use This Calculator

  1. Enter labels for the two alleles.
  2. Enter p, q, or just one of them.
  3. Set the population size for expected counts.
  4. Enter F if you want an adjusted model.
  5. Choose decimal places for the output.
  6. Use normalization if rounded p and q do not sum to 1.
  7. Press Calculate to display the result above the form.
  8. Download CSV or PDF after the result appears.

Article

What This Calculator Does

This calculator converts allele frequency into expected genotype frequency. It uses the Hardy Weinberg model. You can also enter an inbreeding coefficient. That adds a more advanced option. The tool returns genotype ratios, totals, and expected counts. It is useful for teaching, revision, and quick analysis.

Why Allele Frequency Matters

Allele frequency shows how common an allele is in a population. If the first allele has frequency p, the second allele has frequency q. Under equilibrium, p plus q equals 1. Genotype frequencies then follow stable rules. The homozygous first genotype is p squared. The heterozygous genotype is 2pq. The homozygous second genotype is q squared. These relationships are central in population genetics work.

How To Read The Output

The result block lists allele frequencies first. It then shows genotype frequencies. If you add an inbreeding coefficient, the heterozygous value falls as F rises. Homozygous values increase by Fpq each. This helps you compare equilibrium with nonrandom mating. The expected counts section multiplies each genotype frequency by population size. That makes the output easier to interpret in practical settings.

Why Validation Helps

The form checks whether allele frequencies stay within valid limits. If you enter only one allele frequency, the calculator finds the other automatically. If you enter both, their sum should equal 1. You may also normalize them when needed. This helps when rounded values do not sum perfectly. The calculator also checks that adjusted genotype frequencies remain valid before showing the result.

Where This Tool Helps

You can use this calculator in classroom examples, exam practice, and simple research notes. It is also helpful for checking spreadsheets or lecture slides. The export options support record keeping. The example table shows the layout before you test your own values. Overall, the tool gives fast, readable results with minimal setup. That saves time and reduces manual mistakes during routine population calculations.

Practical Notes

This calculator is built for two allele systems. It assumes allele labels are descriptive only. The model works best when frequencies describe the same population. Always review sampling method, rounding, and biological assumptions. If the population is small or selected, real genotype frequencies may differ from the ideal expectation. Use the adjusted option for a closer comparison.

FAQs

1. What do p and q mean?

Use p for the first allele and q for the second. If you enter only one, the calculator finds the other by subtraction from 1.

2. Must p and q add to 1?

Yes. When both values are entered, they should sum to 1. The normalize option can rescale rounded inputs automatically.

3. Can this calculator handle more than two alleles?

No. It supports a two allele model. Multi allele systems need a different formula set and output structure.

4. What does F do?

F is the inbreeding coefficient. Positive values reduce heterozygotes and increase homozygotes. Zero keeps standard equilibrium frequencies.

5. Why enter population size?

Population size converts frequencies into expected counts. Leave it at 1000 or enter your own sample size.

6. Why offer CSV and PDF exports?

CSV is useful for spreadsheets. PDF is useful for sharing results, archiving, or printing summaries.

7. Are these outputs always exact for real populations?

It is most accurate when Hardy Weinberg assumptions are reasonable. Selection, migration, mutation, and small populations can change real outcomes.

8. Can I replace the sample values?

Yes. The example table is only a guide. Replace those values with your own frequencies and sample size.

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