What is body surface area (BSA)?

Body surface area is the measured or estimated total surface area of a human body, expressed in square meters (m²). It is used in medicine to calculate drug dosages — especially for chemotherapy — because BSA correlates better with cardiac output and metabolic rate than body weight alone.

Which BSA formula is most accurate?

No single formula is universally "best." The Mosteller formula is the most widely used in clinical practice due to its simplicity. Du Bois is the historical standard. Haycock is preferred for pediatric patients. Boyd accounts for non-linear weight scaling and is considered accurate across a wide range of body sizes.

What is a normal BSA value?

The average BSA for an adult male is approximately 1.9 m², and for an adult female approximately 1.6 m². A standard reference value of 1.73 m² is commonly used as the "average adult" in renal function calculations.

How is BSA used in chemotherapy dosing?

Oncologists calculate chemotherapy doses by multiplying the drug's dose per m² by the patient's BSA. For example, a drug dosed at 100 mg/m² given to a patient with BSA 1.80 m² would result in a dose of 180 mg. This approach aims to normalize exposure across patients of different sizes.

Is this calculator accurate enough for clinical use?

This tool provides mathematically accurate results for each formula. However, all BSA formulas are estimates and may differ from direct measurement. Always consult a qualified healthcare professional before making any clinical or dosing decisions.

What is the Mosteller formula?

BSA (m²) = √(height in cm × weight in kg ÷ 3600). With inches and pounds it becomes √(height in in × weight in lb ÷ 3131). R. D. Mosteller published it in 1987 as a simpler form of the Gehan and George formula.

How do I work out a drug dose from BSA?

Multiply the dose per square meter by the BSA. A drug given at 75 mg/m² for a BSA of 1.82 m² comes to 136.5 mg. Prescribers and pharmacists set and check the final dose, so use this only to check the arithmetic.

Body Surface Area Calculator

Enter height and weight to instantly calculate BSA in m² using the Mosteller, Du Bois, Haycock, and Boyd formulas, with a side-by-side comparison.

For a 170 cm, 70 kg adult the Mosteller formula gives a body surface area of 1.82 m²: the square root of height in cm times weight in kg, divided by 3600.

Body Measurements

Height

Weight

Enter height and weight, then click Calculate.

Results will show BSA across all four formulas.

Body Surface Area (Mosteller)

— m²

Formula Comparison

Formula	BSA (m²)	Common Use

Height

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Weight

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Range

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Medical disclaimer: This tool is for informational and educational purposes only. BSA formulas are estimates. Always consult a licensed healthcare professional before using BSA values for clinical or drug dosing decisions.

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Quick answer

For a 170 cm, 70 kg adult the Mosteller formula gives a body surface area of 1.82 m²: the square root of height in cm times weight in kg, divided by 3600. Du Bois, Haycock and Boyd land within a few hundredths of that for typical adults. Enter height and weight to compare all four.

Examples

Height and weight	Mosteller	Du Bois	Haycock
160 cm, 60 kg	1.63 m²	1.62 m²	1.64 m²
170 cm, 70 kg	1.82 m²	1.81 m²	1.83 m²
175 cm, 80 kg	1.97 m²	1.96 m²	1.98 m²
180 cm, 90 kg	2.12 m²	2.10 m²	2.14 m²
120 cm, 25 kg (child)	0.91 m²	0.91 m²	0.91 m²

Enter height and weight.

Summary

Enter height and weight to instantly calculate BSA in m² using the Mosteller, Du Bois, Haycock, and Boyd formulas, with a side-by-side comparison.

How it works

Enter your height in centimeters, or switch to feet and inches.
Enter your weight in kilograms, or switch to pounds.
Click Calculate to see your BSA in m² across all four formulas.
Compare the per-formula results in the table on the right.
Click Reset to clear all inputs and start over.

Use cases

Estimate chemotherapy drug dosages based on body surface area.
Calculate pediatric medication doses that scale with BSA.
Assess burn injury surface area coverage in clinical settings.
Compare multiple BSA formulas to understand measurement variability.
Support clinical nutrition and renal function assessments.

Frequently Asked Questions

Last updated: 2026-05-23 · Reviewed by Nham Vu