how many different blood types are there

February 21, 2026

There are 8 main blood types most people are referring to, but scientifically there are actually hundreds of different blood types when all known blood group systems are included.

The simple everyday answer

When people ask “how many different blood types are there?” , they almost always mean the common combination of:

The ABO system: A, B, AB, O

The Rh factor: positive (+) or negative (−)

Put together, this gives 8 common blood types :

A+, A−
B+, B−
AB+, AB−
O+, O−

These 8 are what blood banks, hospitals, and most medical forms use day to day.

The deeper scientific answer

Behind the scenes, red blood cells carry many different antigens (molecules) on their surface, not just A, B, and Rh.

Experts have identified more than 300 different blood group antigens beyond ABO and Rh.

As of 2024, the International Society of Blood Transfusion recognizes 47 separate blood group systems , each with its own set of possible types.

Because each person has a unique combination of these antigens, there are potentially hundreds of distinct blood types , and the list keeps growing as new rare types are discovered.

How this plays out in real life

For everyday purposes like routine transfusions:

Knowing your ABO + Rh type (the 8 common types) is usually enough for safe matching.

For people with certain conditions, multiple transfusions, or rare reactions, doctors may look at other blood group systems to find very closely matched donors.

So:

Short, practical answer: 8 main blood types.

Full scientific answer: dozens of systems and hundreds of possible blood types when all antigens are considered.

Information gathered from public forums or data available on the internet and portrayed here.