What Is a Blood Type Compatibility Checker?
A blood type compatibility checker predicts the possible blood types a child may inherit based on the parents' ABO blood types. Using the principles of Mendelian genetics and the ABO allele system, this tool calculates the probability of each blood type appearing in offspring.
How to Use This Tool
- Select the blood type of Parent 1 from the dropdown (A, B, O, or AB).
- Select the blood type of Parent 2.
- Click Check Compatibility to see all possible child blood types with their probability percentages.
How ABO Blood Type Inheritance Works
The ABO blood group is determined by three alleles: IA, IB, and i. Each person carries two alleles — one from each parent. IA and IB are co-dominant, while i is recessive. This means a person with blood type A can have genotype IAIA or IAi, and similarly for type B.
Type A = IAIA or IAi
Type B = IBIB or IBi
Type O = ii
Type AB = IAIB
Common Parent Combinations
Some combinations always produce a single possible blood type, while others can produce up to three different types. For example, two parents with type O will always have type O children, while an A × B cross can produce children of any blood type (A, B, AB, or O).
Frequently Asked Questions
Can two type O parents have a child with type A or B?
No. Both type O parents carry only the i allele (genotype ii), so all children will inherit ii and have blood type O. This is one of the most predictable combinations.
Does this tool account for the Rh factor (+ or −)?
This tool focuses on the ABO blood group system only. The Rh factor (positive/negative) is inherited independently through a separate gene. A full prediction would require Rh information from both parents as well.
Are these probabilities exact?
The probabilities assume standard Mendelian inheritance and account for the fact that type A and type B individuals may be homozygous or heterozygous. The actual ratios are weighted averages across all possible parental genotype combinations.