Last updated: 2026-06-21

Blood Volume

Total blood volume is the combined volume of plasma and blood cells circulating in the body. This calculator estimates it from height, weight, and sex using Nadler's equations, the method most widely used in clinical practice to plan transfusions and apheresis and to judge the significance of blood loss.

Why blood volume is estimated

Blood volume does not scale neatly with weight alone — a tall, lean person and a shorter, heavier person of the same weight hold different amounts. Procedures that add or remove blood, such as exchange transfusions and therapeutic apheresis, need a reasonable estimate of the starting volume, and the same figure helps interpret how serious a given loss is. A typical adult holds about 4.5 to 5.5 litres, roughly 7 to 8 percent of body weight.

Nadler's equations

With height $h$ in metres and weight $w$ in kilograms, the volume in litres is:

$\mathrm{BV}_{\text{men}} = 0.3669\,h^3 + 0.03219\,w + 0.6041$

$\mathrm{BV}_{\text{women}} = 0.3561\,h^3 + 0.03308\,w + 0.1833$

The cube of height dominates, which is why stature matters so much. The coefficients differ by sex because men tend to have more lean tissue and a higher haematocrit, raising blood volume for the same body size.

Worked example

For a man 1.75 m tall weighing 75 kg:

Just under five litres is typical for an adult man of this size.

Limitations

Nadler's equations were fitted on healthy adults and lose accuracy at the extremes of body size, during pregnancy, and in children, for whom weight-based formulas are preferred. They estimate a starting point, not a measured value. For related body-size measures see the Body Surface Area (BSA) Calculator and the BMI Calculator.