Blood Type Calculator

Explore possible offspring blood types from both parents’ blood types with MiniWebtool’s Blood Type Calculator, using ABO and Rh factor genetics with Punnett square analysis and a probability breakdown.

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Help me understand MiniWebtool's Blood Type Calculator: https://miniwebtool.com/blood-type-calculator/. What can I use it for, what inputs or settings do I need, and how do I use it and understand the output? Walk me through one simple example. Use this page as your source and answer in English.

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Blood Type CalculatorTry it now — free ▼

A+ and O+ parents: child A+ 70.3%, O+ 23.4%, A- 4.7%, O- 1.6%

Pick each parent's ABO group and Rh factor.

Embed Blood Type Calculator Widget

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.

At a Glance

The Blood Type Calculator shows the possible blood types of a child from both parents' ABO types and Rh factors. Results include a probability breakdown, Punnett squares and an Rh incompatibility check.

Blood Type Calculator: features at a glance
Feature	What you get	Good for
Parent inputs	Choose each parent's ABO type (A, B, AB or O) and Rh factor (positive or negative). Example buttons such as A+ x O+ fill the form.	Expectant parents and genetics students
ABO inheritance	Works through the IA, IB and i alleles, where IA and IB are codominant and i is recessive.	Seeing how A, B, AB and O types are passed on
Rh inheritance	Treats Rh+ as dominant (DD or Dd) and Rh- as dd, so two Rh+ parents can have an Rh- child.	Understanding Rh results in a family
Probability breakdown	Lists every possible blood type with its likelihood as an animated bar. A and B types count all possible genotypes with equal probability.	Comparing how likely each child blood type is
Punnett squares	Diagrams show how each allele crosses from parent to child.	Teaching or learning Mendelian genetics
Rh incompatibility	Includes an assessment of Rh incompatibility risk when an Rh-negative mother carries an Rh-positive baby.	Knowing when Rh factors differ between mother and child

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: I^A, I^B, and i. The I^A and I^B alleles are codominant (both expressed when present together), while the i allele is recessive.

Blood Type Calculator: ABO Blood Group System
Blood Type (Phenotype)	Possible Genotypes	Alleles Passed to Child
Type A	I^AI^A or I^Ai	I^A or i
Type B	I^BI^B or I^Bi	I^B or i
Type AB	I^AI^B	I^A or I^B
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:

Blood Type Calculator: Rh Factor (Rh Blood Group System)
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 Calculator: Blood Type Compatibility Chart
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 Calculator: 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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