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Body Surface Area Calculator

Calculate your body surface area using the DuBois formula.

Units

Result

Body Surface Area
1.86 m²

Uses the DuBois & DuBois formula, the most widely used BSA estimate - clinicians sometimes reference it for medication dosing, but any dosing decision should come from a healthcare provider, not this calculator.

About the BSA Calculator

Doctors sometimes need a single number that reflects both your height and weight together, rather than either one alone, and that's exactly what body surface area provides. Our Body Surface Area Calculator applies the DuBois formula, the most widely referenced method for estimating BSA from standard height and weight measurements.

How It Works

The calculator raises your height in centimeters to the power of 0.725 and your weight in kilograms to the power of 0.425, multiplies those two results together, and scales the product by a fixed constant to produce your estimated body surface area in square meters.

BSA (m²) = 0.007184 × height(cm)^0.725 × weight(kg)^0.425

Formula & Methodology

Delafield DuBois and Eugene DuBois published this formula in 1916 after directly measuring the surface area of a small number of subjects using a technique that involved coating the body and mapping the area with paper. The two unusual exponents (0.725 for height and 0.425 for weight) were fit to that measured data rather than derived from any theoretical model of body geometry, yet the formula has held up remarkably well over a century of subsequent comparisons against more modern measurement techniques.

Step-by-Step: Calculating It By Hand

  1. 1Convert height to centimeters and weight to kilograms if needed.
  2. 2Raise height in centimeters to the power of 0.725.
  3. 3Raise weight in kilograms to the power of 0.425.
  4. 4Multiply those two results together, then multiply by the constant 0.007184 for BSA in square meters.

Examples

Average adult

A person who is 173 cm tall and weighs 73 kg has an estimated BSA of approximately 1.86 square meters under the DuBois formula.

Why weight matters less than height here

Because height's exponent (0.725) is larger than weight's (0.425), a given percentage change in height shifts BSA more than the same percentage change in weight.

Advantages

  • Uses the DuBois formula, the most historically referenced and widely cited BSA estimate
  • Combines height and weight into a single physiologically meaningful number
  • Fast calculation from two measurements most people already know
  • Useful reference point for understanding how BSA-based dosing works

Common Mistakes

  • Using a BSA estimate from this or any general calculator for actual medication dosing decisions
  • Entering height or weight in the wrong units, which produces a meaningless result given the formula's specific exponents
  • Assuming BSA and BMI measure the same thing - BSA reflects total body surface, while BMI reflects a weight-to-height-squared ratio used for weight category screening
  • Treating BSA as a fixed personal trait rather than a value that shifts as weight changes

Edge Cases to Watch For

  • BSA estimates from different formulas (DuBois, Mosteller, Haycock) generally agree closely for average-sized adults but can diverge more for infants, children, or people at the extremes of height and weight.
  • Clinical medication dosing based on BSA, particularly for chemotherapy, should always come from a healthcare provider using validated clinical tools, never from a general online calculator.
  • Because the formula multiplies two measurements each raised to a fractional power, small input errors in either height or weight compound less dramatically than they would in a simple linear formula, but accuracy still depends on measuring both carefully.
  • This is a mathematical estimate, not a direct physical measurement, so it carries some inherent error even when height and weight are recorded precisely.

Common Use Cases

  • Understanding how clinicians estimate total body surface area
  • General reference for medication dosing concepts (with dosing itself always left to a healthcare provider)
  • Comparing how BSA changes with different height and weight combinations
  • Educational use for students studying physiology or pharmacology formulas
Written & fact-checked by the Calculateus TeamLast updated August 5, 2026How we verify our formulas

Frequently asked questions

Why does body surface area matter more than weight alone for some medical purposes?

BSA correlates more closely with metabolic rate and organ function than weight alone, since it accounts for both height and weight together - this is why some medications and treatments (particularly chemotherapy) are dosed by BSA rather than weight.

Related calculators

BMI CalculatorCalculate your Body Mass Index (BMI) and see which weight category you fall into.BMI Prime CalculatorCalculate BMI Prime - the ratio of your BMI to the upper limit of normal BMI (25).Calorie CalculatorEstimate your daily calorie needs to maintain, lose or gain weight.BMR CalculatorCalculate your Basal Metabolic Rate - calories burned at complete rest.

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Conclusion

BSA is a useful physiological reference point precisely because it captures the combined effect of height and weight in one number, though real medical dosing decisions always require a healthcare provider's judgment. For a more familiar weight-screening number, our BMI Calculator offers the more commonly referenced measure.

References