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Blood Type Inheritance Calculator

Work out blood type inheritance instantly with clear inputs, formula shown and shareable results.

About Blood Type Inheritance Calculator

Combines parental ABO genotypes allele by allele, treating A and B as codominant and O as recessive.

Formula

ABO inheritance

A and B are codominant and O is recessive, so AO expresses group A and only OO expresses group O

Worked example

With the default values below, Blood Type Inheritance Calculator returns Possible child blood groups of A, B, AB, O. Change any input above and every figure here is recalculated in your browser.

Inputs used

First parent genotypeone of AA, AO, BB, BO, AB, OO
AO
Second parent genotypeone of AA, AO, BB, BO, AB, OO
BO

Results

Possible child blood groups
A, B, AB, O
Chance of group A
25.00%
Chance of group O
25.00%
Chance of group AB
25.00%

Step by step

  1. 1Values used
  2. 2ABO inheritance
  3. 3Possible child blood groups= A, B, AB, O
  4. 4Chance of group A= 25.00
  5. 5Chance of group O= 25.00
  6. 6Chance of group AB= 25.00

Assumptions and limits

  • The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Can two group A parents have a group O child?

Yes, if both are AO heterozygotes, giving a one in four chance.

What about the Bombay phenotype?

Rare hh individuals type as O regardless of their ABO genotype, which is why serology can surprise.

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