Blood Donor Compatibility Calculator — Who Can Donate to Whom
Enter your blood type and instantly see which donors are compatible for red blood cell transfusion, which recipients you can donate to, and roughly what share of the population that covers — based on ABO group and Rh factor.
Your blood type
Blood types whose red cells you can safely receive
How does this calculator work?
For red blood cell transfusions: donors must share the same or narrower ABO antigens than the recipient, and Rh-negative blood is safe for both Rh+ and Rh- recipients. O- is the universal donor (no antigens); AB+ is the universal recipient (no ABO antibodies). Population-weighted, around 44% of people can donate to an O+ recipient.
Formula
How this is calculated
Blood type compatibility for red blood cell transfusions is governed by two main systems: the ABO group (A, B, AB, or O antigens on red cells) and the Rh factor (positive or negative). Receiving incompatible ABO blood causes a severe immune reaction because the recipient already has antibodies against the foreign antigens. Rh incompatibility causes problems mainly in Rh-negative people who have been sensitised — so Rh-negative donors are universally safe, while Rh-positive donors should only go to Rh-positive recipients.
The rules produce a cascade: type O cells have no ABO antigens, so O- is the universal red-cell donor (safe for everyone). AB+ individuals have both A and B antigens and are Rh-positive, so they have no antibodies against any ABO or Rh type and are universal recipients. Between those extremes, each type can safely accept only the subtypes that carry antigens it already tolerates.
Note: this calculator covers whole blood and packed red blood cell compatibility only. Plasma compatibility follows the reverse ABO rule (AB plasma is universal for plasma donation), and platelet compatibility has additional HLA considerations. Always defer to a licensed blood bank for clinical decisions.
Frequently asked questions
O- red cells carry no ABO antigens and no Rh antigen, so any recipient can safely receive them. However, an O- person has anti-A and anti-B antibodies and, having never been exposed to Rh antigen, would mount an immune response to Rh-positive cells — so they can only receive O- blood themselves.
No — plasma compatibility follows the reverse rule. AB plasma contains no anti-A or anti-B antibodies, making AB the universal plasma donor (usable by any blood type). This calculator covers red blood cells only.
Most blood banks recommend a gap of at least 56 days (8 weeks) between whole blood donations. Requirements vary by country and blood bank — always check with your local donation centre.
TG we-Calculate Editorial Team. (2026). Blood Donor Compatibility Calculator — Who Can Donate to Whom [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/blood-donor-calculator
TG we-Calculate Editorial Team. "Blood Donor Compatibility Calculator — Who Can Donate to Whom." TG we-Calculate. 2026. https://we-calculate.com/calculator/blood-donor-calculator.
TG we-Calculate Editorial Team, "Blood Donor Compatibility Calculator — Who Can Donate to Whom," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/blood-donor-calculator
@misc{wecalculate_blood_donor_calculator, title = {Blood Donor Compatibility Calculator — Who Can Donate to Whom}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/blood-donor-calculator}}, year = {2026}, note = {TG we-Calculate} }
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