There are several ways to determine your blood type. One of the easiest and most effective ways is to have your doctor perform a test. A professional will draw blood and then perform two tests on the blood sample: forward typing and reverse typing. During forward typing, the blood sample is mixed with antibodies against type A and B blood. If the blood cells clump together, it means the person has type A or B blood. If there is no clumping, it means the person has type O blood. During reverse typing, the plasma in the blood sample is mixed with red blood cells that have type A and B antigens. If the plasma contains antibodies against either of these antigens, it means the person has a different blood type than the red blood cells.

Another way to determine your blood type is by donating blood. Blood banks test all donated blood for certain diseases and infections before they use it. They also test for blood type. After you donate blood, you can ask for your blood type.

You can also find out your blood type by taking an at-home blood test. The test requires a person to prick a finger with a needle. The kit comes with a card that contains chemicals known as reagents. These test for the presence of antibodies and the Rh factor.