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Punnett Square Calculator

Calculate genotype ratios for a monohybrid cross. Free online Punnett Square Calculator. Calculate punnett square online — fast, accurate, mobile-friendly, no s

P(dominant phenotype)
75%

Derivation

  1. ├── 01Givenp1 = 1, p2 = 1
  2. ├── 02Formula100 × (1-(2-e.p1) / 2 × ((2-e.p2) / 2))
  3. ├── 03Substitute100 × (1-(2-e.1) / 2 × ((2-e.1) / 2))
  4. └── 04Compute P(dominant phenotype)75
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§01What is

Understanding the Punnett Square Calculator

The Punnett Square Calculator computes P(dominant phenotype) from 2 inputs: parent 1 dominant alleles (0-2), parent 2 dominant alleles (0-2). Calculate genotype ratios for a monohybrid cross.

Health metrics give us objective checkpoints against a body that can feel unreliable. Used alongside professional guidance — not in place of it — these numbers help you track progress and spot trends that matter. The Punnett Square Calculator sits in that toolkit — it calculate genotype ratios for a monohybrid cross. Enter your numbers above and the result updates instantly; every step of the math is shown in the Derivation panel so you can see exactly how the answer was reached.

§02The Formula

How it’s calculated

100 × (1-(2-e.p1) / 2 × ((2-e.p2) / 2))

Where

p1
Parent 1 dominant alleles (0-2)
p2
Parent 2 dominant alleles (0-2)
§03Practical Example

Step-by-step walkthrough

Scenario

Apply the formula to a realistic set of inputs: Parent 1 dominant alleles (0-2) = 1, Parent 2 dominant alleles (0-2) = 1.

  1. 01Start by noting the input — Parent 1 dominant alleles (0-2): 1.
  2. 02Start by noting the input — Parent 2 dominant alleles (0-2): 1.
  3. 03Substitute these values into the formula: 100 × (1-(2-e.p1) / 2 × ((2-e.p2) / 2))
  4. 04Compute P(dominant phenotype): the calculator returns 75.
  5. 05Cross-check the answer by opening the Derivation panel above — every line of math is shown so you can follow the computation end-to-end.
§04Variants

Common Punnett Square Problems

The formula gets rearranged depending on which variable you need. Here are the patterns you’ll run into in the real world — find the one that matches your problem and follow the worked steps.

01 · PATTERN

Parent 1 dominant alleles (0-2) halved

p1 = 0.5 (from 1)

Keep every other input at its default and halve the parent 1 dominant alleles (0-2). See how p(dominant phenotype) responds.

  1. 01New Parent 1 dominant alleles (0-2): 0.5
  2. 02Baseline P(dominant phenotype): 75
  3. 03New P(dominant phenotype): 62.5
  4. 04P(dominant phenotype) decreases by 16.7% → use this sensitivity to plan for real-world variation.
02 · PATTERN

Parent 1 dominant alleles (0-2) doubled

p1 = 2 (from 1)

Keep every other input at its default and double the parent 1 dominant alleles (0-2). See how p(dominant phenotype) responds.

  1. 01New Parent 1 dominant alleles (0-2): 2
  2. 02Baseline P(dominant phenotype): 75
  3. 03New P(dominant phenotype): 100
  4. 04P(dominant phenotype) increases by 33.3% → use this sensitivity to plan for real-world variation.
03 · PATTERN

Parent 2 dominant alleles (0-2) halved

p2 = 0.5 (from 1)

Keep every other input at its default and halve the parent 2 dominant alleles (0-2). See how p(dominant phenotype) responds.

  1. 01New Parent 2 dominant alleles (0-2): 0.5
  2. 02Baseline P(dominant phenotype): 75
  3. 03New P(dominant phenotype): 62.5
  4. 04P(dominant phenotype) decreases by 16.7% → use this sensitivity to plan for real-world variation.
04 · PATTERN

Parent 2 dominant alleles (0-2) doubled

p2 = 2 (from 1)

Keep every other input at its default and double the parent 2 dominant alleles (0-2). See how p(dominant phenotype) responds.

  1. 01New Parent 2 dominant alleles (0-2): 2
  2. 02Baseline P(dominant phenotype): 75
  3. 03New P(dominant phenotype): 100
  4. 04P(dominant phenotype) increases by 33.3% → use this sensitivity to plan for real-world variation.
§05FAQ

Frequently asked questions

Yes. The calculator implements the standard formula as documented and returns exact floating-point results. No approximations are used unless noted in the formula.
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