Blood Type Calculator
Find out which blood types your baby could inherit, based on the ABO and Rh blood groups of both parents. Free, instant, and grounded in standard genetic inheritance rules.
Calculate Your Baby’s Blood Type
Select both parents’ blood types below to see every blood group your child could inherit, plus which types are genetically impossible for this pairing.
Parent Blood Types
Enter both parents’ blood groups to calculate possible outcomes
Possible Blood Types
Calculated from standard ABO and Rh inheritance
Parent Blood Type Combinations
Standard ABO inheritance outcomes for every possible pair of parent blood types, showing which child blood types are possible and which are genetically impossible.
| Parent 1 | Parent 2 | Possible Child Types | Impossible Types |
|---|---|---|---|
| O | O | O | A, B, AB |
| O | A | O, A | B, AB |
| O | B | O, B | A, AB |
| O | AB | A, B | O, AB |
| A | A | O, A | B, AB |
| A | B | O, A, B, AB | — |
| A | AB | A, B, AB | O |
| B | B | O, B | A, AB |
| B | AB | A, B, AB | O |
| AB | AB | A, B, AB | O |
Blood Type Calculator FAQ
Everything you need to know about ABO groups, the Rh factor, and how blood type is inherited.
A baby’s ABO blood type is determined by one allele inherited from each parent. The A and B alleles are co-dominant, while O is recessive, so the specific combination of alleles a child receives decides whether they are type A, B, AB, or O. The Rh factor is inherited separately, with Rh-positive dominant over Rh-negative.
Yes. Two parents with type A blood can have a type O child if both carry a hidden recessive O allele (genotype AO), and the same applies to two type B parents. The reference chart above shows exactly which combinations are possible for each pairing.
The Rh factor is a protein that may be present (Rh-positive) or absent (Rh-negative) on red blood cells. Rh-positive is dominant, so a child only ends up Rh-negative if they inherit the recessive Rh-negative allele from both parents. Two Rh-negative parents will always have an Rh-negative child.
A blood type calculator can only rule out paternity in some cases, for instance if a child’s blood type is genetically impossible given the parents’ types. It cannot confirm paternity, since many different people could share the required blood type. DNA testing is the only reliable way to confirm biological parentage.