Which BSA formula should I use?

Mosteller is the most widely used because it is simple and accurate across adults and children. DuBois is the historical standard, and Haycock is often preferred for small children and infants. Most protocols specify which formula to apply.

How is the Mosteller BSA calculated?

Mosteller BSA in square metres equals the square root of height in cm multiplied by weight in kg, divided by 3600. For a 170 cm, 70 kg patient that is the square root of 11900 over 3600, about 1.82 square metres.

Why would I cap the BSA at 2.0?

Some regimens, such as certain capecitabine and carboplatin protocols, cap BSA at a value like 2.0 square metres to avoid overdosing large patients. The tool has an optional cap so the dose uses the smaller of actual or capped BSA.

Does this replace a pharmacist check?

No. This is an educational aid. High-alert and cytotoxic doses must be independently verified against the protocol, the prescribing information, and a second qualified clinician before any drug is given.

Is any patient data sent anywhere?

No. All arithmetic happens locally in your browser. Height, weight, and dose values are never transmitted or stored on a server.

Drug Dose by BSA Calculator

Many specialty drugs, especially cytotoxic chemotherapy agents, are dosed per square metre of body surface area rather than per kilogram. This calculator computes body surface area (BSA) from height and weight using three validated formulas and multiplies by your mg/m² parameter to give a total dose.

How it works

BSA is an estimate of the body’s external surface area in square metres. Three published formulas are supported:

Mosteller: BSA = sqrt( height_cm * weight_kg / 3600 )
DuBois:    BSA = 0.007184 * height_cm^0.725 * weight_kg^0.425
Haycock:   BSA = 0.024265 * height_cm^0.3964 * weight_kg^0.5378

Once BSA is known, the dose is simply BSA * (mg/m^2). If a protocol caps BSA (for example at 2.0 m² for large patients), the tool applies the smaller of the actual or capped BSA before computing the dose.

Example

A patient is 170 cm and 70 kg. Mosteller BSA is the square root of (170 × 70 ÷ 3600), which is about 1.819 m². A regimen ordering 75 mg/m² gives a total dose of 75 × 1.819, roughly 136 mg.

Notes

Always confirm which BSA formula your protocol specifies, and whether a cap applies. The three formulas can differ by a few percent, which matters for narrow-therapeutic-index drugs. This tool is for education and double-checking only and does not replace a pharmacist or protocol verification.