Blood Type Calculator
Free Blood Type Calculator based on ABO genetics. Predict possible blood types of a child from parents' blood types with probability analysis.
About This Calculator
Predict possible blood types of a child based on the parents' blood types using ABO genetic inheritance patterns.
Frequently Asked Questions
How is blood type inherited?
Blood type is determined by the ABO gene with three alleles: A, B, and O. A and B are dominant, O is recessive. Each parent passes one allele. Type A can be AA or AO, Type B can be BB or BO, Type AB is AB, Type O is OO.
Can two O parents have an A child?
No, two type O parents (both OO) can only have type O children. Since O is recessive and neither parent carries A or B alleles, the child can only inherit OO combination.
Can two A parents have an O child?
Yes, if both parents are AO (heterozygous), they have a 25% chance of having a type O child (OO). Each parent has a 50% chance of passing O, and the child needs O from both parents.
What is the rarest blood type?
AB negative is the rarest blood type, found in about 1% of the population. O positive is the most common (37-53% depending on ethnicity). Rh-negative types are less common overall.