How this calculator works
For red cells, donor A and B antigens must be compatible with the recipient, and routine RhD matching allows RhD-negative cells for either RhD type while RhD-positive cells are generally for RhD-positive recipients. Plasma compatibility follows the opposite ABO direction because donor plasma antibodies matter. RhD does not restrict plasma compatibility in this model. These are component rules, not whole-blood rules. Blood banks also assess other antigens, antibodies, crossmatches and special requirements. The result is an estimate for information only and is not medical advice.
Formula
Red cells: donor ABO antigens are a subset of recipient ABO antigens, with routine RhD compatibility. Plasma: recipient ABO antigens are a subset of donor ABO antigens; RhD is not a plasma restriction.
Worked example
O-negative red cells are ABO/RhD compatible with all eight listed types. AB plasma is ABO compatible with all groups, while an AB plasma recipient needs AB plasma; either RhD label can be used for plasma.
Frequently asked questions
Does universal donor mean safe for everyone?
No. The phrase refers to the ABO/RhD component model; other antibodies and clinical requirements still matter.
Why does plasma reverse the ABO pattern?
Plasma transfers donor antibodies rather than a large mass of donor red cells.
Can this decide a transfusion at home?
No. A transfusion service must perform the required compatibility checks and select the component.