Calculator Input
Formula Used
The calculator uses observed genotype counts and compares them with expected Hardy-Weinberg values.
- Total sample:
N = AA + Aa + aa - Genotype frequency:
Genotype count / N - Allele A frequency:
p = (2AA + Aa) / 2N - Allele a frequency:
q = (2aa + Aa) / 2N - Expected genotype frequencies:
p², 2pq, q² - Expected counts:
Expected frequency × N - Chi-square:
Σ((Observed - Expected)² / Expected) - Inbreeding coefficient:
F = (He - Ho) / He
How to Use This Calculator
- Enter the population name and trait name for reporting.
- Change genotype labels when your notation differs from AA, Aa, and aa.
- Enter observed counts for all three genotype groups.
- Select the decimal precision and alpha level.
- Press the calculate button.
- Review observed frequencies, allele frequencies, expected counts, and the HWE result.
- Use the CSV or PDF button to export your calculated table.
Example Data Table
| Population | Trait | AA Count | Aa Count | aa Count | Total | Use Case |
|---|---|---|---|---|---|---|
| Class Sample A | Marker 1 | 50 | 30 | 20 | 100 | Teaching example |
| Field Group B | Marker 2 | 68 | 44 | 18 | 130 | Population check |
| Lab Batch C | Marker 3 | 22 | 51 | 27 | 100 | Heterozygosity review |
Genotype Frequency Analysis Guide
Why Genotype Frequency Matters
Genotype frequency shows how often each genetic form appears in a sample. It is useful in population studies, laboratory teaching, breeding analysis, and quantitative biology. The method starts with simple counts. Those counts are then converted into ratios. Ratios make different sample sizes easier to compare. A group with one hundred subjects can then be compared with a group of one thousand subjects.
Connection With Hardy-Weinberg Balance
The calculator also estimates Hardy-Weinberg expected values. This model assumes random mating, no selection, no migration, no mutation, and a large population. Real samples rarely match every assumption. Still, the model gives a useful reference point. When observed and expected counts are close, the sample may fit equilibrium. When they are far apart, the sample may need deeper review. Possible causes include sampling error, selection, population mixing, or genotyping problems.
Allele Frequency and Heterozygosity
Allele frequency measures the share of each allele. For two alleles, the values are usually called p and q. Their sum should equal one. Heterozygosity shows how many mixed genotypes appear. High heterozygosity can suggest strong variation. Low heterozygosity can suggest limited variation or inbreeding. The inbreeding coefficient compares observed heterozygosity with expected heterozygosity. Positive values usually show fewer heterozygotes than expected.
Using the Result Carefully
A calculated result should support judgment, not replace it. Check data quality before drawing conclusions. Confirm that counts are from the same population. Avoid mixing unrelated groups unless that is the study goal. Use the chart to see large differences quickly. Use the table for exact reporting. Exported files help keep records clear. This makes the calculator useful for lessons, assignments, and early research checks.
FAQs
1. What is genotype frequency?
Genotype frequency is the proportion of one genotype in a population sample. It is calculated by dividing the genotype count by the total number of observed individuals.
2. What does AA mean?
AA usually represents a homozygous dominant genotype. You can rename this label in the form when your study uses different allele symbols.
3. What does Aa mean?
Aa usually represents a heterozygous genotype. It contains one copy of each allele and is used to calculate observed heterozygosity.
4. What does aa mean?
aa usually represents a homozygous recessive genotype. Its count contributes strongly to the frequency of the recessive allele.
5. What is Hardy-Weinberg equilibrium?
Hardy-Weinberg equilibrium is a reference model. It predicts genotype frequencies from allele frequencies when specific population assumptions are met.
6. What does the chi-square value show?
The chi-square value measures the difference between observed counts and expected counts. A larger value usually means a larger difference.
7. Can I export my results?
Yes. After calculation, use the CSV button for spreadsheet data or the PDF button for a simple report file.
8. Is this calculator only for biology?
No. It can support quantitative teaching in physics-style modeling, statistics, data analysis, and population genetics lessons.