Blood Volume Calculator NHS
This independent calculator estimates total blood volume in adults using the published Nadler equation. It uses height, weight and the sex-specific coefficients in the original adult formula. The result is an estimate, not a direct measurement of circulating blood volume.
Adult estimated blood volume calculator
Nadler blood volume formula
For adult men: BV (L) = 0.3669 × height(m)³ + 0.03219 × weight(kg) + 0.6041. For adult women: BV (L) = 0.3561 × height(m)³ + 0.03308 × weight(kg) + 0.1833. These equations estimate blood volume from body size; they do not measure it directly.
Worked example
For a man who is 180 cm tall and weighs 80 kg, the Nadler equation gives approximately 5.32 litres (about 5,319 mL) of estimated blood volume.
What can change actual blood volume?
Actual circulating volume can differ from an anthropometric estimate because of hydration, bleeding, fluid shifts, illness, pregnancy and other physiological or clinical factors. Pregnancy in particular changes blood volume substantially, so this adult reference equation should not be treated as a pregnancy-specific estimate.
Children and infants
This calculator is deliberately limited to adults. Paediatric practice commonly uses age-specific mL/kg estimates rather than the adult Nadler equation. For example, an NHS Lanarkshire paediatric major-haemorrhage protocol uses estimated total blood volume of 90 mL/kg for infants under 1 year and 80 mL/kg for children aged 1 year and over. Those values belong in paediatric clinical protocols and are not mixed into this adult tool.
Clinical limitations
Do not use this estimate alone to determine blood loss, transfusion, fluid replacement or emergency treatment. Formula performance can also vary at extremes of body size; alternative methods such as the Lemmens equation have been developed for higher BMI ranges.
Authoritative and scientific sources
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FAQs
How is adult blood volume estimated?
This calculator uses the Nadler equation, which combines height and weight with sex-specific coefficients.
Is the result my exact blood volume?
No. It is a formula-based estimate rather than a direct physiological measurement.
Can I use this calculator for a child?
No. Children and infants use different age-specific clinical estimates and should be assessed using appropriate paediatric guidance.
Can this tell me how much blood I can safely lose?
No. It must not be used by itself to make decisions about bleeding, transfusion or fluid treatment.
Disclaimer: Educational adult blood-volume estimate only. It does not diagnose blood loss or provide transfusion, fluid or emergency-treatment instructions.