• Blood Facts

  • Blood contains four main components:

    • Red Cells - that help carry oxygen to tissues
    • White Cells - that help the body fight disease and infection
    • Platelets - that help prevent bleeding
    • Plasma - that carries proteins and other clotting factors.

    There are four major blood types: "O", "A", "B", and "AB". Also, a certain substance, the "Rh- factor, is either present on the red cells or absent.

    Approximately 85% of the population has "Rh" factor on their red cells. These people are categorized as "Rh" positive. About 15% of the population lack the "Rh" factor making them "Rh" negative. The blood type breakdown in the United States is as follows:


    Blood Type Number of People % of Population
    O pos 1 in 3 37.4%
    O neg 1 in 15 6.6%
    A pos 1 in 3 35.7%
    A neg 1 in 16 6.3%
    B pos 1 in 12 8.5%
    B neg 1 in 67 1.5%
    AB pos 1 in 29 3.4%
    AB neg 1 in 167 0.6%


    The rarest type of blood is the type that is not available when a patient needs it.

    It takes 24 to 72 hours to type and test blood after a donation and BEFORE it can be used for patient.

    In a crisis, the blood that saves lives is the blood that was donated BEFORE the crisis!

    How Much Blood Does a Person Have?

    • A unit of blood is equal to one pint or two cups.
    • For every 25 lbs. of body weight, you have two pints.
    • A person weighing 125 lbs. has 10 pints of blood in circulation.
    • A person weighing 150 lbs. has 12 pints of blood.