Blood Type Calculator
Predict possible blood types of offspring based on the blood types of both parents using ABO and Rh factor genetics. See Punnett square analysis and probability breakdown.
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About Blood Type Calculator
What Is a Blood Type?
A blood type (also called a blood group) is a classification of blood based on the presence or absence of specific antigens on the surface of red blood cells. The two most important blood group systems are the ABO system and the Rh system. Together, they determine your full blood type, such as A+, B−, AB+, or O−.
Blood types are inherited from your parents through genes located on chromosome 9 (ABO) and chromosome 1 (Rh). Understanding how blood types are passed down is essential for predicting a child's blood type and for managing pregnancy-related Rh incompatibility.
How Blood Type Inheritance Works
Blood type inheritance follows Mendelian genetics. Each person inherits two alleles for their ABO blood type (one from each parent) and two alleles for their Rh factor. The combination of these alleles determines the blood type.
ABO Blood Group System
The ABO system has three alleles: IA, IB, and i. The IA and IB alleles are codominant (both expressed when present together), while the i allele is recessive.
| Blood Type (Phenotype) | Possible Genotypes | Alleles Passed to Child |
|---|---|---|
| Type A | IAIA or IAi | IA or i |
| Type B | IBIB or IBi | IB or i |
| Type AB | IAIB | IA or IB |
| Type O | ii | i only |
Rh Factor (Rh Blood Group System)
The Rh system is determined by the presence (Rh+) or absence (Rh−) of the D antigen. The D allele is dominant over the d allele:
| Rh Type | Possible Genotypes | Notes |
|---|---|---|
| Rh+ (Positive) | DD or Dd | D is dominant; only one D allele is needed |
| Rh− (Negative) | dd | Must inherit d from both parents |
Blood Type Compatibility Chart
Blood type determines who you can safely donate blood to and receive blood from:
| Blood Type | Can Donate To | Can Receive From |
|---|---|---|
| O− | All types (Universal Donor) | O− |
| O+ | O+, A+, B+, AB+ | O−, O+ |
| A− | A−, A+, AB−, AB+ | O−, A− |
| A+ | A+, AB+ | O−, O+, A−, A+ |
| B− | B−, B+, AB−, AB+ | O−, B− |
| B+ | B+, AB+ | O−, O+, B−, B+ |
| AB− | AB−, AB+ | O−, A−, B−, AB− |
| AB+ | AB+ | All types (Universal Recipient) |
Blood Type Distribution (US Population)
| Blood Type | Percentage |
|---|---|
| O+ | 37.4% |
| A+ | 35.7% |
| B+ | 8.5% |
| O− | 6.6% |
| A− | 6.3% |
| AB+ | 3.4% |
| B− | 1.5% |
| AB− | 0.6% |
How to Use the Blood Type Calculator
- Select the mother's blood type — Choose her ABO type (A, B, AB, or O) and Rh factor (positive or negative) from the dropdowns.
- Select the father's blood type — Choose his ABO type and Rh factor.
- Click "Calculate Blood Type" — The calculator will process all possible genetic combinations.
- Review the probability breakdown — See each possible blood type with its likelihood shown as animated bars.
- Explore the Punnett squares — Scroll down for detailed genetic diagrams showing how each allele crosses from parent to child.
Frequently Asked Questions
What blood type will my child have?
Your child's blood type depends on the alleles inherited from both parents. Each parent passes one ABO allele and one Rh allele. This calculator shows all possible blood types and their probabilities based on both parents' blood types.
Can two parents with type O blood have a child with type A or B?
No. Two type O parents both have the genotype OO, so they can only pass O alleles to their children. All children will be type O. However, in extremely rare cases, mutations or the Bombay phenotype can cause unexpected results.
What is Rh incompatibility and why does it matter?
Rh incompatibility occurs when an Rh-negative mother carries an Rh-positive baby. The mother's immune system may produce antibodies against the baby's Rh-positive blood cells, potentially causing hemolytic disease of the newborn in subsequent pregnancies. This is preventable with RhoGAM injections.
Why are the probabilities shown as ranges rather than exact numbers?
Blood types A and B can each have two possible genotypes (AA or AO for type A, BB or BO for type B), and Rh-positive can be DD or Dd. Since we cannot determine the exact genotype from the blood type alone, the calculator considers all possible genotype combinations with equal probability.
Can two Rh-positive parents have an Rh-negative child?
Yes. If both Rh-positive parents carry the recessive d allele (genotype Dd), there is a 25% chance in each pregnancy that the child will inherit dd and be Rh-negative. The calculator accounts for this possibility.
Reference this content, page, or tool as:
"Blood Type Calculator" at https://MiniWebtool.com/blood-type-calculator/ from MiniWebtool, https://MiniWebtool.com/
by miniwebtool team. Updated: 2026-03-03
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