A simple ABO & Rh Punnett square for educational use.
A simple Punnett-square tool for the classic ABO and Rh blood-type inheritance model. Pick what's known about each parent's genotype to see the possible outcomes for a child.
Why genotype, not just blood type? A and B are dominant over O, so a person with Type A blood could genetically be AA or AO — you can't always tell from a blood type alone. If you don't know which, "carrier" (AO/BO) is the more common assumption unless you've had genetic testing.
ABO Punnett square
Rh factor Punnett square
Educational tool only. This models the classic Mendelian ABO/Rh pattern — it is not a paternity test, a medical device, or a substitute for genetic counseling or clinical blood typing. Rare variants (e.g. the Bombay phenotype, cis-AB) exist outside this simple model. See Terms.
Acronyms on this page: ABO — the ABO blood group system: the classification system behind the A, B, AB and O blood types.
FAQ
Can this determine a child's exact blood type?
No — it shows probabilities based on classic Mendelian inheritance of the ABO and Rh genes. The actual outcome for any specific child depends on which allele each parent happens to pass on, which is random each time.
Why does Type A or B have two genotype options?
A and B are both dominant over O, so a person with Type A blood could be genetically AA or AO, and a Type B person could be BB or BO. Only DNA testing can tell you which one you actually have.
Is Rh positive or negative dominant?
Rh positive (D) is dominant over Rh negative (d). A person who is Rh positive could be DD or Dd; only someone with two recessive (dd) copies is Rh negative.
Why might my child's actual blood type differ from this chart?
This tool models the standard, well-known ABO/Rh pattern. Rare biological exceptions (such as the Bombay phenotype) fall outside this model, and any concern about parentage should go to a doctor or accredited testing service, not a calculator.
