Body Surface Area (BSA) Calculator

🧍 Body Surface Area Calculator

Enter height and weight to get body surface area in square metres using the three formulas clinicians quote most often, the figure behind many drug and chemotherapy doses.

Quick answer: Mosteller BSA = √(height in cm × weight in kg ÷ 3600). For 170 cm and 70 kg, √(11,900 ÷ 3,600) = 1.82 m².

Not rated yet · Updated October 16, 2026 · Free · No sign-up

Body surface area (Mosteller)

1.82 m²

for 170 cm and 70 kg

Mosteller	1.82 m²
Du Bois	1.81 m²
Haycock	1.83 m²

Average of three: 1.82 m²
Mosteller in cm²: 18,181

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Preview

How body surface area is calculated

Several formulas estimate the area of the skin from height and weight. The calculator shows the three most common so you can see how closely they agree.

Mosteller = √(H × W ÷ 3600) · Du Bois = 0.007184 × W^0.425 × H^0.725 · Haycock = 0.024265 × W^0.5378 × H^0.3964

H is height in centimetres and W is weight in kilograms. Imperial inputs are converted first (1 in = 2.54 cm, 1 lb = 0.4536 kg).

Example: 170 cm and 70 kg. Mosteller: 170 × 70 = 11,900; ÷ 3,600 = 3.306; square root = 1.82 m². Du Bois gives 1.81 m² for the same person.

Typical values

Group	Typical BSA
Newborn	about 0.25 m²
Child, 10 years	about 1.1 m²
Adult woman	about 1.6 m²
Adult man	about 1.9 m²

Where BSA is used

Dosing chemotherapy and some other drugs in mg/m².
Indexing cardiac output (cardiac index) and kidney function (GFR normalised to 1.73 m²).
Estimating burn area and fluid needs.

Medical dosing must be set by a clinician. This calculator is for information only.

Frequently asked questions

Which BSA formula should I use?

Mosteller is the most widely used because it is easy to compute by hand and agrees closely with the others for adults. Du Bois is the historical standard and Haycock is often preferred for infants and children.

What is a normal body surface area?

Average adults have roughly 1.9 m² for men and 1.6 m² for women. Children have much smaller values, around 0.25 m² for a newborn.

Why is BSA used for drug doses?

Many chemotherapy drugs and some other medicines are dosed in mg per m² because body surface area tracks metabolic rate and blood volume better than weight alone.

Is BSA the same as the skin area of my body?

It is an estimate of skin area derived from height and weight, not a direct measurement. Individual build can make the real figure differ a little.

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