Blood donation is usually between 200-400ml. The amount of blood to be donated depends on the weight of the donor. For lighter weight people, such as those around 60kg, a blood donation of 200-300ml is usually sufficient. For people with high body weight, such as those around 80kg, the amount of blood donated can reach 400ml, because the amount of blood in the human body is proportional to the body weight, generally accounting for 7%-8% of the body weight. For a person weighing around 70kg, the body’s blood volume is between 4200-4500ml, and for a person weighing 80kg, the total blood volume can reach between 4500-4800ml. Therefore, people with high body weight can donate more blood, which can reach 400ml, and people with lower body weight, 200-300ml of blood can be donated.