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Blood Volume Calculator

Estimate your total blood volume with the Nadler formula

How it is calculated

The tool uses Nadler's equations, which estimate blood volume from body size. With height h in metres (you enter centimetres) and weight W in kilograms: for males V = 0.3669 × h³ + 0.03219 × W + 0.6041 and for females V = 0.3561 × h³ + 0.03308 × W + 0.1833, giving litres. Millilitres are litres × 1000. The height is cubed because volume scales with the cube of body size, and weight is added linearly. A sex must be chosen. This is a population-based estimate for adults of typical build: it can be off for very muscular or very obese people, children, pregnancy and certain medical conditions, and it is not a measurement.

Worked example

A man 175 cm tall weighing 70 kg. Height in metres: 1.75, and 1.75³ = 5.359. Terms: 0.3669 × 5.359 = 1.966, 0.03219 × 70 = 2.253, plus the constant 0.6041. Total = 1.966 + 2.253 + 0.604 = 4.82 L, which is 4,824 mL.

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Common mistakes

  • Entering height in metres or feet, when the field expects centimetres, which makes the cubed term nonsense.
  • Entering weight in pounds instead of kilograms.
  • Selecting the wrong sex; the two equations give noticeably different values for the same body size.
  • Treating the estimate as a measured value for clinical decisions such as transfusion planning.
  • Expecting accurate results for children, pregnant women or people at the extremes of body composition.

About this calculator

This calculator estimates total blood volume using the Nadler formula, which combines height, weight, and biological sex (separate equations for men and women, since body composition differs) into a volume in liters, since blood volume can't be measured directly without specialized tracer techniques.

Anesthesiologists and surgeons use estimated blood volume to judge how much blood loss a patient can tolerate during an operation, and nursing and medical students use the same formula to learn the concept. It's an estimate for reference and education, not a substitute for a clinical measurement.

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