The amount of blood in the human body generally corresponds to about 7% to 8% of a person's body weight, but this can vary based on age, sex, body size, and other factors such as altitude or pregnancy. Typical blood volumes by group:

• Adults: An average adult weighing between 150 to 180 pounds (approximately 65 to 80 kg) has about 4.5 to 5.7 liters (1.2 to 1.5 gallons) of blood, which is roughly 10.5 pints or about 7-8% of body weight

• Men vs. Women: Adult males typically have more blood volume than females due to larger body size and muscle mass. For example, a 200-pound male may have about 5.7 liters, while a 165-pound female may have about 4.3 liters

• Pregnant women: Blood volume increases by 30 to 50% during pregnancy to support fetal development

• Children: Children have about 70 to 75 milliliters of blood per kilogram of body weight. For instance, an 80-pound child may have approximately 2.65 liters of blood

• Infants: Full-term babies have about 75 to 85 milliliters of blood per kilogram. A baby weighing about 8 pounds (3.6 kg) will have roughly 270 mL of blood

Blood volume can also be influenced by environmental factors such as living at high altitudes, where the body produces more blood to compensate for lower oxygen levels

. In summary, the average adult human body contains about 4.5 to 5.7 liters of blood, which is about 7-8% of body weight, with variations depending on age, sex, pregnancy status, and environmental factors.