Standard ABO and Rh blood type compatibility rules — the same chart used across blood banks and medical references.
How it works
Each of the eight blood types has a fixed, well-established list of types it can donate to and receive from, based on ABO and Rh compatibility rules.
What this does not include
This does not include a substitute for an actual clinical cross-match — real transfusions always require lab verification before use, regardless of blood type on record.
How to use this calculator
- Select your blood type.
A worked example
O− has no A, B, or Rh antigens for a recipient’s immune system to react against, which is why it’s compatible as a donor to all eight blood types in an emergency — the “universal donor.”
AB+ already carries A, B, and Rh antigens, so it doesn’t react to donor blood carrying any combination of those — making it the universal recipient, compatible with donations from all eight types.
What the terms mean
| Term | Meaning |
|---|---|
| ABO type (A, B, AB, O) | Which antigens (A, B, both, or neither) are present on red blood cells |
| Rh factor (+/−) | Presence or absence of the Rh(D) antigen |
Edge cases worth knowing
An Rh− recipient can only safely receive Rh− blood — exposure to the Rh antigen from Rh+ blood can trigger an immune response, even if the ABO type matches perfectly.
This chart is a reference, not a substitute for clinical cross-matching. Real transfusions always require laboratory verification before use, regardless of the blood type on record.
Frequently asked questions
Why is O− called the “universal donor”?
Because it lacks the A, B, and Rh antigens that could trigger an immune reaction, making it compatible with recipients of any blood type in an emergency.
Why is AB+ called the “universal recipient”?
Because it already carries A, B, and Rh antigens, so it doesn’t react to donor blood that also carries any combination of those antigens.
Can Rh+ blood be given to an Rh− recipient?
No — an Rh− recipient can only safely receive Rh− blood, since exposure to the Rh antigen can trigger an immune response.
This calculator is for general informational purposes only and does not constitute medical advice. Consult a qualified healthcare professional for guidance specific to your situation.
