Dihybrid Cross & Punnett Square Calculator

Predict Genotype and Phenotype Ratios for Two Traits

Enter the genotypes of two parents to calculate all possible offspring genotypes and phenotypes using a Punnett square. Supports any valid dihybrid cross (e.g., AaBb x AaBb, AABb x aabb).

Examples

Try these common dihybrid crosses:

Classic Mendel Cross (AaBb x AaBb)

Dihybrid Cross

Both parents are heterozygous for both traits. This produces the classic 9:3:3:1 phenotype ratio.

Parent 1: AaBb

Parent 2: AaBb

Allele A Desc: A: Yellow, a: Green

Allele B Desc: B: Round, b: Wrinkled

Homozygous Dominant x Homozygous Recessive (AABB x aabb)

Dihybrid Cross

All offspring will be heterozygous (AaBb) and show dominant phenotypes.

Parent 1: AABB

Parent 2: aabb

Allele A Desc: A: Tall, a: Short

Allele B Desc: B: Purple, b: White

Heterozygous x Homozygous Recessive (AaBb x aabb)

Dihybrid Cross

Shows a 1:1:1:1 ratio for each genotype and phenotype.

Parent 1: AaBb

Parent 2: aabb

Allele A Desc: A: Black, a: Brown

Allele B Desc: B: Long, b: Short

Homozygous Dominant x Heterozygous (AABB x AaBb)

Dihybrid Cross

All offspring will have at least one dominant allele for each gene.

Parent 1: AABB

Parent 2: AaBb

Allele A Desc: A: Red, a: Yellow

Allele B Desc: B: Smooth, b: Rough

Other Titles
Understanding Dihybrid Cross & Punnett Square Calculator: A Comprehensive Guide
Master dihybrid genetics with step-by-step explanations, real-world examples, and common pitfalls.

What is a Dihybrid Cross?

  • Definition and Historical Context
  • Mendelian Laws and Dihybrid Inheritance
  • Why Use a Punnett Square?
A dihybrid cross examines the inheritance of two different traits, each controlled by different genes. It helps predict the probability of offspring inheriting combinations of alleles.
Mendel's Experiments and the 9:3:3:1 Ratio

Classic Dihybrid Crosses

  • AaBb x AaBb produces 9:3:3:1 phenotype ratio.
  • AABB x aabb produces all AaBb offspring.

Step-by-Step Guide to Using the Calculator

  • Inputting Parent Genotypes
  • Understanding the Output Table
  • Interpreting Genotype and Phenotype Ratios
Enter the genotypes for both parents. The calculator generates all possible gametes, combines them, and displays the Punnett square with genotype and phenotype ratios.
How to Read the Results

How to Use

  • Input: AaBb x AaBb. Output: 16 squares, 9:3:3:1 ratio.
  • Input: AABB x aabb. Output: All AaBb.

Real-World Applications of Dihybrid Crosses

  • Agriculture and Plant Breeding
  • Animal Genetics and Breeding
  • Medical Genetics and Disease Prediction
Dihybrid crosses are used in plant and animal breeding to predict trait inheritance, and in medicine to understand genetic disorders involving multiple genes.
Practical Uses in Science and Industry

Applications

  • Breeding crops for disease resistance and yield.
  • Predicting coat color and fur length in animals.

Common Misconceptions and Correct Methods

  • Mixing Up Genotype and Phenotype
  • Incorrect Gamete Formation
  • Misreading the Punnett Square
Many students confuse genotype (gene combination) with phenotype (observable trait). It's also common to make mistakes in gamete formation or interpreting the Punnett square.
Tips for Accurate Calculations

Avoiding Mistakes

  • Always list all possible gametes.
  • Double-check dominant and recessive allele notation.

Mathematical Derivation and Examples

  • Gamete Formation and Combinations
  • Calculating Probabilities and Ratios
  • Worked Example: AaBb x AaBb
Each parent produces four types of gametes. The Punnett square is a 4x4 grid, and each cell represents a possible offspring genotype. Ratios are calculated by counting occurrences.
Example Calculation

Math in Action

  • AaBb x AaBb: Gametes = AB, Ab, aB, ab. 16 combinations.
  • Count each genotype and convert to percentage.