300 mL to 400 mL
According to a Circular prepared jointly by AABB, the American Red Cross, America’s Blood Centers, and the Armed Services Blood Program:
Depending upon the collection system used, a single whole blood donation typically contains either 450 mL (+/- 10%) or 500 mL (+/- 10%) of blood collected from allogeneic blood donors. After plasma is removed, the resulting component is RBCs, which has a hematocrit between 65% to 80% and a usual volume between 225 mL and 350 mL. Red Blood Cells additive solutions (AS) may be mixed with the red cells remaining after removal of nearly all of the plasma to extend the shelf life (see Table 2). The typical hematocrit of AS RBCs is 55% to 65%, and the volume is approximately 300 to 400 mL.