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Estimated Blood Volume Calculator

Enter height, weight and sex to estimate total blood volume by Nadler's method.

How it is calculated

Nadler's regression estimates total blood volume in litres from height h (entered in centimetres, converted to metres inside the tool), body weight W in kilograms and sex:

Men: BV = 0.3669·h³ + 0.03219·W + 0.6041
Women: BV = 0.3561·h³ + 0.03308·W + 0.1833

The tool also shows the volume in millilitres (litres × 1,000) and per kilogram of body weight, BV in mL ÷ W. Any sex value other than female uses the male equation. Height and weight must be above 0. The equations are population averages for adults, so the result is an estimate that does not account for age, body fat, pregnancy or illness.

Worked example

A woman 165 cm tall and 60 kg. Height in metres: h = 1.65, so h³ = 4.4921. Height term: 0.3561 × 4.4921 = 1.5996. Weight term: 0.03308 × 60 = 1.9848. Add the constant: 1.5996 + 1.9848 + 0.1833 = 3.7677 L, shown as 3.77 L. In millilitres that is 3,768 mL, and dividing by her 60 kg gives 62.8 mL/kg. A man of the same height and weight comes out higher, at 4.18 L.

Try this example →

Common mistakes

  • Entering height in metres, such as 1.65. The field expects centimetres, and 1.65 cm produces a volume of about 2.2 L, far too low. Use 165.
  • Entering weight in pounds. The equation is calibrated in kilograms, so a 132 lb person typed as 132 gives an inflated blood volume.
  • Choosing the wrong sex. The two equations have different constants and give about 0.4 L difference at 165 cm and 60 kg.
  • Using the result as a measured value for dosing or transfusion decisions. It is a population-based estimate and must be interpreted by a clinician.
  • Applying it to children, very obese patients or pregnant women. The formulas were not built to cover those groups, and the result there is less reliable.

Sources

About this calculator

Nadler's equations, published in 1962, estimate a person's total blood volume from their height, weight, and sex using separate regression formulas for men and women (blood volume correlates with lean body mass more than with weight alone, which is why the formulas differ by sex and include height). This calculator takes those three inputs and returns the estimated total blood volume in liters.

Estimated blood volume is used clinically to guide transfusion planning, calculate allowable blood loss during surgery, dose certain medications, and manage severe blood loss or shock in trauma and critical care. Anesthesiologists, surgeons, and blood bank staff commonly reference Nadler-derived estimates because directly measuring blood volume (via dye or radioisotope dilution) is impractical for routine care.

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Comments (1)

  • Editorial team

    Use the per-kilogram line as a plausibility check on the typed inputs: the default adult man of 180 cm and 75 kg comes out at 5.16 L, which is 68.8 mL per kg. A number far outside that range usually means height was typed in metres or weight in pounds. The equation is an average for adults, so it is not for children or for pregnancy, and a clinician decides what a measured value means. Which setting do you use this in?

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