Understand your blood type and discover who you can help. Learn the science behind blood compatibility and why it matters.
Your blood type is determined by proteins called antigens on the surface of your red blood cells. The main system is called ABO, which gives you four possible types:
Has A antigens on red blood cells
Has B antigens on red blood cells
Has both A and B antigens
Has neither A nor B antigens
In addition to ABO, your blood has another important marker called the Rh factor. You're either Rh-positive (has the D antigen) or Rh-negative (doesn't have it).
Has the D antigen. About 85% of people are Rh positive.
Lacks the D antigen. About 15% of people are Rh negative.
Combining ABO and Rh gives you 8 possible blood types: A+, A-, B+, B-, AB+, AB-, O+, and O-.
Mixing incompatible blood types can cause a life-threatening reaction where the immune system attacks the transfused blood cells.
Can be given to anyone in emergencies because it has no A, B, or Rh antigens.
Can receive any blood type because they have all antigens.
Explore the relationships between key blood banking concepts. Hover over nodes to highlight connections.
Hover over nodes to highlight relationships, or click any node to navigate to its glossary definition
💡 Tip: Click any node to navigate to its glossary term definition
It could save your life or someone else's. Get tested today and consider donating blood.