Health Calculators

Blood Type Calculator

This tool will calculate the possible blood type for a child.

Blood Type Calculator

Parent 1


Parent 2


Table of contents

Antibodies, antigens
The ABO System
The Rh system
Blood group tests
Giving blood
What is the rarest blood type?
There are four major blood groups (types of blood types): A, B, ABC, and O. Your parents' genes determine which blood group you will be.
Each group can either be RhD positive (or RhD negative), eight blood groups total.

Antibodies, antigens

The blood is composed of red blood cells (white blood cells), platelets, and a liquid called plasma. The antibodies and antigens found in the blood identify your blood group.
Antibodies can be defined as proteins found in plasma. They are part of your body's natural defenses. They detect foreign substances like germs and alert the immune system, which destroys them.
Antigens can be described as protein molecules on red blood cells' surfaces.

The ABO System

The ABO system defines four main blood groups:
blood group A – has antigens A on red blood cells, with anti-B antibodies present in the plasma
Blood group B has anti-A antibodies present in plasma from blood groups B and A.
Blood group O has no antigens. However, plasma contains both anti–A and anti–B antibodies.
Blood group AB consists of both A- and B-antigens but no antibodies
Blood group O is the most prevalent. Forty-eight percent of the UK population has blood group O.
The wrong ABO group could cause severe complications if you receive blood. For example, group B blood will be given group A blood. Their anti-A antibodies would attack the group A cells.
This is why people with group B blood cannot be given group A blood.
Because group O red cells don't have A and B antigens, they can safely be given to any other group.
The NHS Blood and Transplant (NHSBT) website provides more information on the various blood groups.

The Rh system

Red blood cells may contain another antigen, known as the RhD antibody. Your blood group is RhD-positive if this is present. If it's not present, your blood type is RhD positive.
This means you could be in any one of the eight blood groups.
A positive RhD (A+).
An RhD negative (A-)
B RhD Positive (B+).
B RhD negative (B-)
O RhD positive, (O+).
O RhD negative (O-)
AB RhD Positive (AB+).
AB RhD negative (AB-)
About 85% are RhD positive. 36% have O+, the most frequent type.
O RhD positive blood (O+) can be safely given to anyone in most cases. When the blood type is not known immediately, it's commonly used.
It is safe for most recipients as it does not contain any A, B, or RhD antibodies on the cell surface. Furthermore, it is compatible and compatible with all ABO and Rh blood groups.
The Rh system is described on the NHS Blood and Transplant (NHSBT) website.

Blood group tests

Mixing red cells with different antibody solutions will help determine your blood type. For example, if you have anti-B antibodies on your red cells, they will clump together.
If the blood doesn't react with any anti-A or Anti-B antibodies, it's likely to be blood group O. You can identify your blood type by performing a series test with different antibodies.
A blood transfusion is taken from one individual and given to another. Your blood will then be tested against donor cells with ABO or RhD antigens. If you don't react, donor blood of the same ABO or RhD type may be used.

Giving blood

Although most people believe they can give blood, only 1 in 25 of those, who can do so will. If you're eligible, you may donate blood.
You are healthy and fit.
Weigh at least 50kg (7st 12lb).
You are between 17-66 and 70 years old (or 70 if your blood has been donated before).
I have given blood in the past two years to someone over 70


Pregnant women should always have their blood tested to see if they fall within the appropriate blood group. Complications could occur if the mother is RhD positive, but the child inherits RhD-positive blood.
RhD-negative RhD+-negative women of childbearing age should only ever receive RhD+ blood.

What is the rarest blood type?

AB-negative is the least common of the eight major blood types - it affects only 1%.
Despite it being rare, the demand for AB-positive blood remains low. We don't have any problems finding donors with AB negativity blood.
Some blood types are, however, rare or in high demand.
This includes the subtype that is used often to treat sickle cell.
While only 2% have it, demand rises by 10-15% annually.
People with rare blood types and high demand make them essential donors.

Parmis Kazemi
Article author
Parmis Kazemi
Parmis is a content creator who has a passion for writing and creating new things. She is also highly interested in tech and enjoys learning new things.

Blood Type Calculator English
Published: Thu Feb 03 2022
In category Health calculators
Add Blood Type Calculator to your own website