Blood Type Calculator

Calculate the possible blood types of a child from the parents blood types.

Parents

Mother's blood type

Rh factor

Father's blood type

Rh factor

Child's possible blood types

Choose blood types above - the possible blood types of the child update instantly.

Probabilities assume each compatible genotype is equally likely and are estimates, not a guarantee. A child's blood type can only be confirmed by a blood test - this tool is for education and interest only.

How inheritance works

Pick parents' blood types to see the Punnett square for each possible genotype pairing.

Tool Introduction

The ABO blood group is inherited from both parents. Each parent passes on one allele: A or B are dominant, while O is recessive - so a person with type A can carry AA or AO, type B can carry BB or BO, type AB always carries AB, and type O carries OO.

This calculator works out every compatible genotype pairing for the parents' blood types and Rh factor, then builds the Punnett square for each pairing. Possible blood types of the child are shown with relative probabilities, plus a clear "can be / cannot be" summary.

Everything runs locally in your browser - nothing is sent anywhere.