Last updated October 10, 2026 · Report an error
Blood transfusion compatibility follows fixed ABO/Rh rules: O− is the universal donor (compatible with all 8 types), and AB+ is the universal recipient (can receive from all 8 types). This tool checks compatibility between any donor and recipient blood type pairing.
How it works
Select a donor and recipient blood type. The tool checks standard ABO/Rh compatibility rules and reports whether that specific donation would be compatible, along with the full list of compatible recipients for that donor type.
- Enter donor blood type.
- Enter recipient blood type.
- Click Calculate to see your results.
Examples
Universal donor
O− blood can be given to any of the 8 blood types — it's the universal donor type used in emergencies when a patient's blood type isn't yet known.
Who should use it
- Learning ABO/Rh compatibility rules.
- Quick reference before a blood drive or donation.
Industry applications
- Healthcare and medical education
- Blood bank and transfusion services
Advantages
- Covers all 8 standard ABO/Rh blood types.
- Shows the full compatible-recipient list for a donor, not just one pairing.
Limitations
- Reference information only — not a substitute for real cross-match testing.
Common mistakes to avoid
- Assuming Rh factor doesn't matter — an Rh-negative recipient generally shouldn't receive Rh-positive blood, even if the ABO type matches.
Best practices
- Use this as a quick reference, but always defer to an actual blood bank's testing before any real donation or transfusion.
Tips
- Remember AB+ is the universal RECIPIENT (can receive from anyone) while O− is the universal DONOR (can give to anyone) — these are opposite ends of the compatibility chart.
Frequently asked questions
No — this is standard published reference information. Any real transfusion requires an actual blood bank's cross-match testing regardless of what ABO/Rh type is on record.
O− red blood cells carry neither A nor B surface antigens nor the Rh(D) antigen, so they don't trigger an immune reaction in a recipient of any other type.