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Body Surface Area Calculator

Computes body surface area in square metres from height and weight using the Mosteller and Du Bois formulas, as used for chemotherapy and other weight-independent dosing.

When to use

You need BSA for drug dosing, cardiac index or physiological normalisation.

Do not use when: You need body composition or BMI; BSA does not indicate fatness.

Formula

Mosteller: BSA = √(H·W / 3600). Du Bois: BSA = 0.007184 · W^0.425 · H^0.725. Haycock: BSA = 0.024265 · W^0.5378 · H^0.3964. H in cm, W in kg.

Inputs

Parameter	Type	Unit	Required	Description
`weight_kg`	number	kg	yes	Body weight in kilograms. Range: > 0, ≤ 700
`height_cm`	number	cm	yes	Height in centimetres. Range: ≥ 30, ≤ 300

Outputs

Output	Type	Unit	Description
`bsa_mosteller_m2`	number	m²	√(height_cm × weight_kg / 3600).
`bsa_dubois_m2`	number	m²	0.007184 × weight^0.425 × height^0.725.
`bsa_haycock_m2`	number	m²	0.024265 × weight^0.5378 × height^0.3964 (often used in paediatrics).

Example

70 kg, 175 cm: {"weight_kg":70,"height_cm":175} → {"bsa_mosteller_m2":1.845,"bsa_dubois_m2":1.847,"bsa_haycock_m2":1.85}

GET https://tttkmbb.com/api/v1/calculate/body-surface-area?weight_kg=70&height_cm=175

Machine access

API: GET https://tttkmbb.com/api/v1/calculate/body-surface-area (query parameters) or POST with a JSON body {"inputs": {...}}
Schema: https://tttkmbb.com/api/v1/calculators/body-surface-area · Markdown: https://tttkmbb.com/health/body-surface-area.md · JSON definition: https://tttkmbb.com/health/body-surface-area.json
MCP: server https://tttkmbb.com/mcp, tool run_calculator with calculator_id="body-surface-area"
OpenAPI operationId: calculate_body_surface_area
Freshness: static. Authentication: none. Rate limit: fair use (see rate limits).

Sources

FAQ

Which formula do hospitals use?

Mosteller is the most common because it is simple and within 1–2% of Du Bois for adults; Haycock is favoured for infants and children.

Related calculators

BMI Calculator — A different height–weight index used for weight classification.