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Body Surface Area Calculator | Du Bois Formula

A body surface area (BSA) calculator estimates total body surface in square metres from weight and height. It uses the Du Bois formula BSA = 0.007184 × W^0.425 × H^0.725 — the most widely referenced BSA equation for chemotherapy dosing, GFR indexing and cardiac output normalisation.

Last updated: September 2026 · Free · No sign-up required

Results

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Quick reference

Reference BSA values (Du Bois):

Height	Weight	BSA
160 cm	55 kg	1.58 m²
170 cm	70 kg	1.80 m²
175 cm	70 kg	1.85 m²
185 cm	90 kg	2.14 m²

medication Dose scaling

Many IV drug doses are written as mg/m² — BSA converts the protocol number into your personal dose.

favorite Cardiac index

Cardiac output divided by BSA gives cardiac index; 2.5–4.0 L/min/m² is the normal adult range.

monitor_heart GFR indexing

Kidney filtration rate is reported per 1.73 m² of BSA so results compare across body sizes.

science Formula spread

Du Bois and Mosteller agree within ~1% for adults; agreement drifts at extremes of paediatric size.

lightbulb A real example — dosing a 70 kg adult

Height 175 cm, weight 70 kg, protocol dose 50 mg/m².

Result: BSA ≈ 1.85 m², so the dose is 50 × 1.85 = 92.5 mg.

What this means: Capping rules (e.g., dose-cap at 2.0 m²) exist because very high BSA correlates more with adiposity than with drug clearance — always confirm against the protocol.

Formula & methodology

Formula: BSA = 0.007184 × Weight(kg)^0.425 × Height(cm)^0.725

The Du Bois formula (1916)

Du Bois & Du Bois fit a linear model to nine subjects' measured surfaces; a century of validation kept it the clinical default. For a 70 kg, 175 cm adult: BSA = 0.007184 × 70^0.425 × 175^0.725 ≈ 1.85 m².

Alternatives: Mosteller √(H×W/3600) gives nearly identical results (±1%) and is easier by hand; Haycock and Gehan-George fit children better. Most adult oncology protocols specify Du Bois or Mosteller explicitly.

Typical adult range: 1.6–2.0 m² (men average ≈1.9, women ≈1.7).

Authoritative source: Mosteller 1987

Frequently asked questions

How is body surface area calculated?

The clinical standard is the Du Bois formula: BSA = 0.007184 × weight(kg)^0.425 × height(cm)^0.725. A 70 kg, 175 cm adult has a BSA of about 1.85 m².

What is a normal BSA?

Most adults fall between 1.6 and 2.0 m². Men average around 1.9 m², women around 1.7 m²; values outside 1.2–2.5 m² are uncommon.

Which BSA formula should I use?

Du Bois for general and oncology use, Mosteller for quick mental math (it agrees within 1% for adults), and paediatric-validated equations like Haycock for small children.

Why is medication dosed by BSA?

Surface area scales with metabolic mass better than raw weight, so cytotoxic drugs dosed mg/m² produce more consistent blood levels across body sizes than mg/kg.

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