Generally speaking, the total amount of blood in the body of an adult is closely related to his or her own body weight. The weight of blood in the body of an adult accounts for about 7%-8% of his or her own body weight, and the greater the body weight, the more the total amount of blood in the body, and conversely, the lighter the body weight, the total amount of blood in the body will decrease accordingly. An adult weighing about 70kg has about 5.0kg of total blood in the peripheral blood, which translates into a volume of about 5000ml. On the contrary, for an adult weighing about 60kg, the weight of blood is about 4.2-4.5kg, which translates into a volume of about 4200-4500ml. Therefore, the total amount of blood in an adult’s body is closely related to his or her own weight, and because of this, clinical blood donation is generally not required for lighter weight people, such as adult males weighing less than 50kg and adult females weighing less than 45kg.