Humans are usually described as having 8 common blood types, but scientifically there are many more possible types when all known blood group systems are included.

Quick scoop

  • In everyday medicine, blood is classified into:
    • 4 main ABO groups: A, B, AB, O.
* Each can be RhD positive or RhD negative, giving **8 standard blood types** : A+, A−, B+, B−, AB+, AB−, O+, O−.
  • These 8 are the ones talked about for blood donation, transfusions, and most hospital use.

Beyond the basic 8

  • Red blood cells carry many more surface markers (antigens) than just ABO and Rh. At least 350+ antigens beyond A, B and Rh are known.
  • As of 2024, the International Society of Blood Transfusion recognizes 47 blood group systems , each with its own set of possible blood types.

So how many blood types really?

  • If the question is “how many blood types are there in humans” for everyday use?
    • Answer: 8 main blood types (A, B, AB, O × Rh+ or Rh−).
  • If the question is “how many can exist biologically?”
    • Answer: hundreds of distinct blood types when all blood group systems and their antigen combinations are considered, and the list is still growing as new variants are discovered.

Fun (and important) details

  • Some extremely rare types exist, such as Rh-null (“golden blood”) , with fewer than about 50 known people worldwide, plus other rare systems like Duffy, Kell, Lutheran and Kidd.
  • These rare blood types can make transfusions very challenging, which is why detailed blood typing and specialized donor registries matter for certain patients.

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