Blood Type Calculator

How Blood Type Works

Blood type is determined by two genetic systems:

• ABO System: Controlled by three alleles (A, B, O). A and B are codominant, both dominant over O.
• Rh Factor: Positive (+) is dominant over negative (-).

Your blood type is written as ABO type followed by Rh (e.g., A+, O-, AB+).

ABO Blood Types

• Type A: Genotype AA or AO
• Type B: Genotype BB or BO
• Type AB: Genotype AB (codominant)
• Type O: Genotype OO (recessive)

There are 4 blood types and 6 possible genotypes in the ABO system.

Rh Factor

• Rh Positive (+): Genotype ++ or +-
• Rh Negative (-): Genotype --

About 85% of people are Rh positive. Rh negative is recessive and requires two negative alleles.

Inheritance Examples

Example 1: Parent 1 (A+) × Parent 2 (B+)

If both are AO and +-, possible children:

• AB+, AB-, A+, A-, B+, B-, O+, O-
• This couple could have children with any blood type!

Blood Type Distribution

Global average distribution:

• O+ : 38%
• A+ : 34%
• B+ : 9%
• O- : 7%
• A- : 6%
• AB+ : 3%
• B- : 2%
• AB- : 1%

Important Notes