About the Blood Volume Calculator
An average adult carries somewhere around 4.5 to 6 liters of blood, but the exact amount depends on body size and sex. This calculator estimates your total blood volume with Nadler’s equation, the formula most often used in medicine and blood banking, which combines height and weight rather than weight alone.
It is useful for students learning physiology, blood donors curious about what share of their blood a donation removes, and clinicians who want a quick estimate before thinking about allowable blood loss or transfusion volumes. Results are shown in liters, millilitres per kilogram and US pints, alongside a simple weight-based estimate (about 70 mL/kg for men and 65 mL/kg for women) for comparison.
Nadler’s formula was derived from healthy adults, so it is less accurate for children, pregnancy, extreme obesity or athletes with unusual body composition. It is an estimate, not a measurement — actual blood volume can only be measured with specialised tracer tests.
With the default inputs, the estimated blood volume is 5.15 L. Change any value above to recalculate instantly.
How to use the blood volume calculator
- 1Choose US or metric units.
- 2Select your sex.
- 3Enter your height and weight.
- 4Read your estimated blood volume in liters, mL/kg and pints.
Formula and method
Nadler, Hidalgo and Bloch (1962) fitted these equations to measured blood volumes in healthy adults. Height H is in metres and weight W in kilograms, and the result BV is in liters. Cubing height captures how blood volume scales with overall body size, while the weight term adds the contribution of body mass.
In US mode your height and weight are converted to metres and kilograms first. The comparison figure uses a simple rule of thumb of about 70 mL per kg for men and 65 mL per kg for women with average build; lean, muscular people tend to be higher and people with more body fat lower, because fat tissue holds relatively little blood.
- BV
- Estimated total blood volume (L)
- H
- Height (m)
- W
- Body weight (kg)
Worked examples
Man, 5 ft 10 in, 170 lb
Height is 1.778 m and weight 77.1 kg. Nadler gives 0.3669 × 1.778³ + 0.03219 × 77.1 + 0.6041 ≈ 5.15 L, or about 67 mL/kg — close to the 5.4 L from the 70 mL/kg rule of thumb.
Woman, 165 cm, 60 kg
With the female equation, 0.3561 × 1.65³ + 0.03308 × 60 + 0.1833 ≈ 3.77 L, about 63 mL/kg. The simple 65 mL/kg rule gives 3.9 L.
Tall man, 190 cm, 95 kg
A larger frame means more blood: 0.3669 × 1.9³ + 0.03219 × 95 + 0.6041 ≈ 6.18 L, or about 65 mL/kg.
Frequently asked questions
How much blood is in the human body?+
Most adults have roughly 4.5 to 6 liters of blood, about 7% of body weight. Men usually have more than women of the same size, and larger people have more than smaller people.
What is Nadler’s formula?+
Nadler’s formula estimates blood volume from height, weight and sex using separate equations for men and women. It was published in 1962 and remains the standard estimate in many hospitals and blood banks.
How much blood can you lose safely?+
Healthy adults usually tolerate losing up to about 15% of blood volume with few symptoms. Losses beyond roughly 30% can cause shock and need urgent treatment. A standard one-pint (about 470–500 mL) donation removes roughly 8–12%, depending on body size.
How long does it take to replace donated blood?+
Plasma volume is typically restored within about 24–48 hours, while red blood cells take several weeks to fully replace, which is why donors must wait between whole-blood donations.
Is this accurate for children?+
No. Nadler’s equations were developed in adults. Children are usually estimated by weight — roughly 75–80 mL/kg for children and higher for newborns — so ask a clinician for paediatric estimates.
This tool gives general estimates and is not medical advice. Talk to a doctor or qualified professional about your health, diet or training.