Blood Volume Calculator (Nadler formula)

Understanding the blood volume calculator — concept and principle

This calculator estimates total blood volume with Nadler's formula from sex, height and weight, and splits it into plasma and red cell volume if you enter the haematocrit. It also shows the blood volume per kilogram. Anaesthesia and surgery teams, students and people curious about physiology use it.

Nadler: height³ + weight — with the default inputs: 4.72 L.

How it is calculated

Men: BV (L) = 0.3669 × H³ + 0.03219 × W + 0.6041
Women: BV (L) = 0.3561 × H³ + 0.03308 × W + 0.1833
H = height in metres; W = weight in kg
Plasma volume ≈ BV × (1 − haematocrit); red cell volume ≈ BV × haematocrit
Blood volume per kg = BV × 1,000 ÷ W

The principle

Nadler and colleagues (1962) measured blood volume with radioactive tracers in healthy adults and fitted equations to height and weight. Height enters as a cube because body volume scales roughly with the cube of linear size; weight adds a further term. The split into plasma and red cells is simple and ignores the slightly lower haematocrit of the whole body compared with a vein sample. The formula is widely used before surgery and in blood-loss estimates.

Worked example

Defaults: man, 172 cm, 70 kg, haematocrit 44%.

H³ = 1.72³ = 5.088; 0.3669 × 5.088 = 1.867.
0.03219 × 70 = 2.253.
BV = 1.867 + 2.253 + 0.604 = 4.72 L = 4,724 mL; 67 mL/kg.
Plasma = 4.724 × 0.56 = 2.65 L; red cells = 4.724 × 0.44 = 2.08 L.

Each point is the calculator re-run with only “Your height (cm)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

Your height (cm)	Total blood volume (L)
43	2.89
86	3.09
129	3.65
172	4.72
215	6.5
258	9.16
344	17.79

How to read the result

Typical adult blood volume is around 4.5–5.5 L for men and less for women, depending on size. The per-kilogram figure is lower in people with more body fat, because fat tissue has relatively little blood. Results are less accurate for children, pregnancy, very high body fat and severe illness.

Common mistakes

Entering height in centimetres in the cube term; the formula uses metres.
Using a haematocrit from a different day or condition.
Applying the adult formula to children.
Treating the estimate as a measured value.

Keep in mind: Not medical advice. Clinical decisions about fluids and transfusion are made by the care team using measurements and monitoring.

Frequently asked questions

How much blood does an adult have?

Roughly 4.5–5.5 litres for an average adult man; the formula estimates it from height and weight.

What is Nadler's formula?

A 1962 equation estimating blood volume from height cubed and weight, separately for men and women.

Why is blood volume per kg lower in obesity?

Fat tissue contains less blood than lean tissue.

Sources: Nadler SB, Hidalgo JU, Bloch T, "Prediction of blood volume in normal human adults", Surgery 1962;51(2):224–232

Checked 9 Nov 2026. Nadler SB, Hidalgo JU, Bloch T, “Prediction of blood volume in normal human adults”, Surgery 1962;51(2):224–232; coefficients as listed in AmSECT/AACP “Goal Directed Perfusion Equations” (2021).

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