The body contains approximately 6 quarts (5.6 liters) of blood. 6 quarts of blood means that about 7% of the average person's body weight is blood. This amount of blood circulates through the body completely three times each minute. During the average human lifetime, the heart pumps about 42 million gallons (158,987,295 liters) of blood.
More blood facts:
- An average human heart beats about 100,000 times per day or 35 million times per year.
- The most common blood type is O-positive. About 37% of the world's population has O-positive blood.
- The least common type is AB-negative — only about 0.45% of the world's population has this type.
- Salt is added to donated blood to keep it from clotting.