How is BSA calculated?

BSA is calculated using regression formulas that take height (cm) and weight (kg) as inputs. Mosteller (1987): BSA = √(H × W / 3600) — the most common formula in US practice, fast and easy to remember. DuBois & DuBois (1916): BSA = 0.007184 × H^0.725 × W^0.425 — the original formula. Haycock, Gehan & George are alternatives used in cardiology and oncology. All four agree within ~3% for healthy adults. Our body surface area calculator implements all four so you can compare.

What is a normal body surface area?

Normal adult BSA ranges from about 1.5 m² (small adults) to 2.3 m² (large adults), with an average of ~1.9 m² for men and ~1.7 m² for women. Children: ~0.25 m² at birth, ~1.0 m² by age 10, ~1.5 m² by age 15. The pediatric growth charts report BSA percentiles. BSA scales roughly with the 2/3 power of body weight — taller and heavier people have more BSA, but the relationship is sub-linear (doubling weight increases BSA by ~60%, not 100%). Our body surface area calculator gives you the exact figure.

Why is BSA used for chemotherapy dosing?

Most chemotherapy agents are dosed per m² of BSA (mg/m²) rather than per kg of body weight. The rationale is that BSA correlates better than weight with metabolic rate, blood volume, and drug clearance. BSA-based dosing also produces more consistent drug exposure across patients of different body sizes. Examples: carboplatin uses the Calvert formula (mg = AUC × (GFR + 25)), paclitaxel at 175 mg/m², cisplatin at 75-100 mg/m². Our body surface area calculator provides the BSA value used in these dose calculations.

What is the Mosteller formula?

The Mosteller formula (1987) is the most widely used BSA formula in US clinical practice. BSA (m²) = √(H × W / 3600), where H is height in cm and W is weight in kg. It is a simplification of the older DuBois formula and matches it within 1% for healthy adults. The formula was published in a brief letter in the New England Journal of Medicine and quickly became the standard because it's easy to remember and calculate. Our body surface area calculator uses Mosteller as the primary result.

What is the DuBois formula?

The DuBois & DuBois formula (1916) is the original BSA formula, derived from measurements on just 9 subjects. BSA = 0.007184 × H^0.725 × W^0.425. Despite the small original sample, it remained the standard for 70+ years and is still referenced in many pharmacology references. Modern formulas (Mosteller, Haycock, Gehan) were developed with much larger samples and tend to be slightly more accurate. Our body surface area calculator shows the DuBois result alongside the others for historical reference.

Which BSA formula is best?

For healthy adults, all four formulas in our body surface area calculator (Mosteller, DuBois, Haycock, Gehan) agree within ~3%. Mosteller is the easiest to remember and is the current US standard for clinical dosing. For pediatric patients, Haycock is often preferred because it was validated on a larger pediatric sample. For very obese or very thin patients, no single formula is dramatically more accurate — the formulas have systematic errors at the extremes. DEXA-based 3D body scanning is more accurate but rarely done. Most clinicians use Mosteller by default.

Body Surface Area Calculator — Mosteller, DuBois, Haycock

Quick Answer: Body Surface Area by Mosteller Formula

These examples show estimated body surface area for common height and weight combinations.

Weight	Height	BSA	Category
50 kg	160 cm	1.48 m²	Small adult
60 kg	165 cm	1.65 m²	Average adult
70 kg	175 cm	1.85 m²	Average adult
80 kg	180 cm	2.00 m²	Large adult
90 kg	175 cm	2.06 m²	Large adult
100 kg	185 cm	2.23 m²	Large adult

Mosteller (1987): BSA = √(H × W / 3600). DuBois formula also valid.

What is a body surface area (BSA) calculator?

A body surface area (BSA) calculator estimates the total surface area of your skin from your height and weight. BSA is a key clinical metric used to dose chemotherapy, normalize cardiac output (cardiac index), adjust renal function (eGFR/1.73 m²), assess burn percentages, and dose certain other drugs. Our body surface area calculator applies the Mosteller (1987), DuBois & DuBois (1916), Haycock (1978), and Gehan & George (1970) formulas — the most widely used regression equations for BSA in clinical practice.

Body Surface Area (BSA) Calculator

Unit system

Height

feet

inches

Weight (lbs)

Body Surface Area (Mosteller 1987)

1.84 m²

≈ 19.8 sq ft

Compare formulas

Formula	BSA (m²)	Use case
Mosteller (1987)	1.844	Most common in US clinical practice
DuBois & DuBois (1916)	1.848	Original; still used in pharmacology
Haycock (1978)	1.846	Pediatric & adult cardiology
Gehan & George (1970)	1.853	Common in oncology

Common clinical uses of BSA

Chemotherapy dosing: most chemo agents are dosed in mg/m² (e.g. carboplatin, cisplatin, paclitaxel).
Cardiac index: cardiac output (L/min) / BSA = cardiac index (L/min/m²).
Renal function: GFR is normalized to 1.73 m² (standard adult BSA).
Burn assessment: percent of BSA burned guides fluid resuscitation (Parkland formula).
Drug dosing (select): certain antibiotics, immunosuppressants, and biologics.

Average adult BSA: ~1.9 m² (men ~2.0, women ~1.7). Children range from ~0.25 m² at birth to ~1.5 m² by age 12. Source: Mosteller RD. 'Simplified calculation of body-surface area.' N Engl J Med 1987;317:1098. All four formulas in our body surface area calculator agree within ~3% on healthy adults; differences widen for very small (infants) or very large (obese) patients.

Body Surface Area (BSA) Formulas

Mosteller RD (1987). Simplified calculation of body-surface area. N Engl J Med 317:1098. pubmed.ncbi.nlm.nih.gov

DuBois D, DuBois EF (1916). A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med 17:863-871.

Haycock GB, Schwartz GJ, Wisotsky DH (1978). Geometric method for measuring body surface area. J Pediatr 93:62-66.

Gehan EA, George SL (1970). Estimation of human body surface area from height and weight. Cancer Chemother Rep 54:225-235.

Frequently asked questions

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A body surface area calculator estimates the total area of your skin from height and weight. BSA is widely used in clinical medicine: chemotherapy dosing (mg/m²), cardiac output normalization to cardiac index (L/min/m²), renal function normalization (eGFR per 1.73 m²), and burn assessment (% BSA burned). Our body surface area calculator applies four validated formulas (Mosteller 1987, DuBois & DuBois 1916, Haycock 1978, Gehan & George 1970) so you can see how each one estimates your BSA from the same height and weight.

How to calculate body surface area (BSA)

Our body surface area calculator applies four validated formulas (Mosteller, DuBois, Haycock, Gehan) to estimate BSA from height and weight.

1
Pick your units
Toggle between US (lb, in) and metric (kg, cm). The body surface area calculator converts internally to kg and cm — the units used by all four formulas.
2
Enter height and weight
Type your height and current weight. The body surface area calculator does not need age or sex — BSA formulas are sex-neutral.
3
Read the result
The body surface area calculator shows your BSA in m² (Mosteller formula by default) and square feet, plus a comparison table of all four formulas. Most adults fall between 1.5-2.2 m²; average is ~1.9 m². Use the Mosteller value for chemo dosing or cardiac index unless your provider specifies otherwise.

Body Surface Area (BSA) Calculator

Quick Answer: Body Surface Area by Mosteller Formula

What is a body surface area (BSA) calculator?

Body Surface Area (BSA) Calculator

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Common clinical uses of BSA

Body Surface Area (BSA) Formulas

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