Estimated Blood Volume Calculator (Nadler)
Estimated Blood Volume Calculator (Nadler)
Estimate total blood volume from height, weight and sex using Nadler's equations — the standard for apheresis and exchange transfusion planning.
Estimated Blood Volume (Nadler)
Nadler equationMale, height 170 cm, weight 70 kg
Formula (Nadler equations)
Women: BV = 0.3561 × height(m)³ + 0.03308 × weight(kg) + 0.1833
- height
- metres, cubed — captures body frame size
- weight
- kg
- result
- litres of whole blood; multiply by 1000 for mL
Worked example
Male, height 170 cm, weight 70 kg
height = 1.70 m, so height³ = 4.913
0.3669 × 4.913 = 1.803
0.03219 × 70 = 2.253
1.803 + 2.253 + 0.6041 = 4.66 L
Nadler compared with weight-based rules of thumb
| Method | Estimate for this patient |
|---|---|
| Nadler equation | 4.66 L |
| 70 mL/kg rule (adult male) | 4.90 L |
Estimating whole blood volume, and when it matters
Nadler’s equations, published in 1962 from measurements of body volume and haematocrit in healthy adults, remain the standard method for estimating total blood volume from height, weight and sex. They are used to plan apheresis procedures, to calculate exchange transfusion volumes in neonates, and to set the maximum allowable blood loss before transfusion is likely to be needed during major surgery — calculations that need an absolute volume, not a per-kilogram estimate.
The result is in litres; multiply by 1000 for millilitres. Separate equations are used for men and women because, at the same height and weight, women have a higher proportion of body fat and a lower proportion of blood-rich lean tissue, which the different coefficients in the female equation reflect.
Simpler weight-based rules — roughly 70 mL/kg in adult men, 65 mL/kg in adult women, 80 mL/kg in children, and 85 to 90 mL/kg in neonates — are adequate for quick bedside estimation and avoid the cubic height term entirely. They diverge from Nadler’s estimate as weight rises, because adipose tissue is relatively poorly perfused and blood volume per kilogram actually falls in obesity; a flat per-kilogram rule overestimates blood volume in a heavier patient, while Nadler’s equation, built from height as well as weight, does not.
Frequently asked questions
What is Nadler's equation used for?
Estimating total blood volume for apheresis planning, exchange transfusion in neonates, and calculating the maximum allowable blood loss before transfusion is likely to be needed in surgery.
Why are there separate equations for men and women?
At the same height and weight, women carry proportionally more fat and less blood-rich lean tissue, and the different coefficients in the equations account for that.
How do I convert the result to millilitres?
Multiply the litre result by 1000. A result of 4.66 L is 4660 mL.
Why not just use a mL/kg rule?
Flat per-kilogram rules are fine for bedside estimation but overestimate blood volume in obesity, where blood volume per kilogram falls because fat tissue is relatively poorly perfused; Nadler’s height-based equation accounts for this better.
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References
- Nadler SB, Hidalgo JU, Bloch T. Prediction of blood volume in normal human adults. Surgery. 1962;51(2):224–32.
- Pearson TC et al. Interpretation of measured red cell mass and plasma volume in adults: Expert Panel on Radionuclides of the International Council for Standardization in Haematology. Br J Haematol. 1995;89(4):748–56.