Blood Type Compatibility Calculator
Which blood types you can donate red blood cells to and receive them from.
Covers standard red blood cell (whole blood) transfusion compatibility only — plasma and platelet donation follow different, roughly reversed rules. Not medical advice; real transfusions always require lab cross-matching regardless of known blood type.
Can donate red blood cells to
Can receive red blood cells from
For informational and educational purposes only — not medical advice, and not a substitute for consulting a qualified professional about your specific situation. TrueMeasureKit is not liable for decisions made based on these results. See our Terms of Service.
Why O- and AB+ sit at opposite extremes
Red blood cells carry A, B, and Rh surface markers that a recipient's immune system can react to if they don't recognize them as "self." O- cells carry none of those markers, so any immune system can accept them — making O- the universal donor. AB+ cells carry all of them, which means an AB+ person's immune system already recognizes every marker as familiar, letting them safely receive from any type — the universal recipient.
Frequently asked questions
What makes O-negative a 'universal donor'?
O-negative red blood cells lack the A, B, and Rh(D) antigens that trigger immune reactions, so they can generally be given to any blood type in an emergency — which is why O-negative is in especially high demand at blood banks.
Does blood type compatibility apply the same way to plasma?
No — plasma compatibility is actually the reverse of red blood cell compatibility. This calculator covers red blood cell donation and receiving, which is the far more common clinical scenario.