The average volume of blood in a healthy adult human body is about 5 to 6 liters. Blood is a vital fluid that performs many important functions, such as carrying oxygen and nutrients to cells, removing waste products, and helping fight infections. Blood is made up of red blood cells, white blood cells, platelets, and plasma. The amount of blood varies based on factors like age, sex, and body size, but generally, adults have around 7% to 8% of their total body weight as blood. Maintaining the right blood volume is essential for the heart to pump blood properly and keep all the body organs working well. Losing too much blood can cause serious health problems, which is why blood donation and transfusion are carefully managed.