To estimate blood volume in an adult, calculate 8% of the body weight; adult males average 5-6 liters of blood and females 4-5 liters. An adult weighing 70 kg would have an estimated 5.6 liters of blood.
Estimating the total blood volume in a healthy adult is primarily based on average body weight percentages. Blood makes up about 8 percent of an adult's body weight. For example, adult males average about 5 to 6 liters of blood, and females average about 4 to 5 liters. While individual variations such as body composition and health status can affect total blood volume, for those without obesity, a rough estimate can be made using these figures.
One method to estimate blood volume is to use the person's body weight and multiply it by the percentage that blood contributes to body weight, which is 8%. Therefore, an adult weighing 70 kilograms would have an estimated blood volume of 5.6 liters, as 70 kg x 8% (or 0.08) equals 5.6 liters.
So, while this method provides a gross estimation and may not account for all individual differences, it is often sufficient for general purposes where a precise measurement of blood volume is not necessary.