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Blood Type Calculator

Predict possible blood types of a child from parents.

Last updated: June 13, 2026

Calculator

Parent 1 Blood Type

Parent 2 Blood Type

Results

Possible Blood TypesA, B, AB, O

Parent 1Type A

Parent 2Type B

Number of Possibilities4

How to Use This Calculator

1Select Parent 1's blood type.
2Select Parent 2's blood type.
3View all possible blood types for the child.

Formula Explanation

Blood type inheritance follows Mendelian genetics. A and B are codominant, O is recessive. Each parent contributes one allele.

Possible combinations depend on parental genotypes

Variables:

Parent TypesABO blood types of both parents

AllelesGenetic variants each parent can pass on

Worked Examples

Parent 1: Type A, Parent 2: Type B

1. A can be AA or AO
2. B can be BB or BO
3. Possible combinations: A, B, AB, O

Result: Child could be type A, B, AB, or O

Why Use This Calculator

Predict baby's possible blood types.
Understand blood type inheritance.
Educational genetics tool.
Prepare for medical situations.

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Tips & Best Practices

Type O negative is the universal red blood cell donor.
AB positive is the universal plasma donor.
Blood type can affect susceptibility to certain diseases.
Both parents must carry the O allele for a child to be type O.

Common Mistakes to Avoid

❌ Thinking blood type is determined by one parent.

✅ Both parents contribute one allele. The combination determines the child's blood type — neither parent alone decides it.

❌ Expecting an exact result instead of possibilities.

✅ Without knowing each parent's exact genotype (which requires testing), we can only predict possible types. A parent who is Type A could be AA or AO.

Frequently Asked Questions

Can two Type O parents have a non-O child?

No. Two Type O parents (both OO genotype) can only have Type O children. This is one of the only certain predictions in blood type genetics.

What is the rarest blood type?

AB negative is the rarest (about 1% of the US population). O positive is the most common (about 38%).

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Disclaimer: This calculator is provided for informational and educational purposes only. Results are estimates and should not be used as a substitute for professional advice. RediCalc.com makes no guarantees regarding the accuracy, completeness, or suitability of any calculations. Always consult a qualified professional before making financial, health, construction, or other important decisions.

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