Allele Frequency Calculator
Calculate allele and genotype frequencies in a population using the Hardy-Weinberg equilibrium model.
This free online allele frequency calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
Number of individuals with genotype AA.
Number of individuals with genotype Aa.
Number of individuals with genotype aa.
Results
Dominant Allele Frequency (p)
0.8
Recessive Allele Frequency (q)
0.2
Total Population
500
How to Use This Calculator
Enter your input values
Fill in all required input fields for the Allele Frequency Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The Allele Frequency Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the Allele Frequency Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About Allele Frequency Calculator
The allele frequency calculator determines how common each version of a gene (allele) is within a population. Allele frequencies are the foundation of population genetics and the Hardy-Weinberg equilibrium principle. By counting individuals of each genotype — homozygous dominant (AA), heterozygous (Aa), and homozygous recessive (aa) — you can compute p (the frequency of the dominant allele) and q (the frequency of the recessive allele). These frequencies are essential for predicting genotype ratios in the next generation, estimating carrier rates for genetic diseases, and detecting whether evolutionary forces such as selection, drift, or migration are acting on a population. The Hardy-Weinberg model predicts that in the absence of these forces, allele and genotype frequencies remain constant across generations, a state known as genetic equilibrium.
The Math Behind It
Formula Reference
Hardy-Weinberg Allele Frequencies
p = (2·AA + Aa) / 2N; q = 1 − p
Variables: p = frequency of dominant allele; q = frequency of recessive allele; AA = homozygous dominant count; Aa = heterozygote count; N = total individuals
Worked Examples
Example 1: MN blood group in a village
A population of 500 has 320 AA, 160 Aa, and 20 aa individuals.
The dominant allele frequency is 0.80 and the recessive allele frequency is 0.20.
Common Mistakes & Tips
- !Forgetting to multiply homozygote counts by 2 when counting alleles.
- !Assuming Hardy-Weinberg equilibrium holds without testing — always verify with a chi-squared test.
- !Applying the formula to loci with more than two alleles without adjusting for multiple allele frequencies.
- !Confusing allele frequency with genotype frequency.
Related Concepts
Used in These Calculators
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Frequently Asked Questions
What does it mean if a population is not in Hardy-Weinberg equilibrium?
It means one or more evolutionary forces (natural selection, genetic drift, mutation, migration, or non-random mating) are acting on the population, causing allele or genotype frequencies to deviate from the expected p², 2pq, q² distribution.
Can this calculator handle more than two alleles?
This version is designed for two-allele (biallelic) loci. For multiallelic loci (e.g., ABO blood group with three alleles), the allele-counting method still works but you need to track each allele separately.
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