| Formula | BSA (m²) | Copy |
|---|---|---|
| {{ r.name }} | {{ format(r.value) }} |
Body surface area is an estimate of the external area of the human body expressed in square metres, and it helps scale physiological processes and medication dosing when body size matters. Many clinical settings compare body surface area formulas to check that dosing decisions remain consistent across methods.
Enter stature and body mass, select a formula, then read the estimate alongside the average of all methods and a simple index that shows how close the chosen result is to that average. You can optionally cap the value at a ceiling for protocols that limit exposure and convert a regimen given in milligrams per square metre into a single total dose.
A typical example is a person who is 170 centimetres tall and weighs 65 kilograms, where most formulas return a result near 1.76 square metres and agree within a small margin. If a regimen is 120 milligrams per square metre, the tool multiplies the effective estimate and rounds to a whole milligram so the number is easy to act on.
Formulas are empirical and are not a substitute for professional judgement, and unusual body composition or clinical circumstances can shift interpretation. For consistency, measure carefully, use the same units each time, and avoid mixing sources of height and weight.
This tool provides informational estimates and does not substitute professional advice.
Body Surface Area (BSA) approximates the two dimensional outline of the body using height and weight. The calculator evaluates five established formulas and also reports the arithmetic mean of those results to provide a stable reference. An index expresses the selected result as a percentage of that mean, which highlights small method differences without changing the underlying estimate.
BSA here is computed from height in centimetres or metres and weight in kilograms or pounds. A dose helper multiplies the effective BSA by a regimen in milligrams per square metre to produce a single rounded milligram total. An optional ceiling limits the effective BSA for protocols that cap dosing.
| Symbol | Meaning | Unit/Datatype | Source |
|---|---|---|---|
| H | Height | cm or m | Input |
| W | Weight | kg or g | Input or derived |
| BSA | Body surface area | m² | Derived |
| Mean | Arithmetic mean of all formulas | m² | Derived |
| Index | Selected result relative to mean | % | Derived |
Worked example — Height 170 cm and weight 65 kg.
Other methods for the same inputs: Du Bois 1.754 m², Haycock 1.754 m², Gehan & George 1.763 m², Boyd 1.762 m². Mean 1.757 m²; a Mosteller result is about 99.7% of the mean.
With a regimen of 120 mg/m² and no cap, total dose ≈ 212 mg; if capped at 1.60 m², dose = 192 mg.
Height and weight are converted consistently before computation. Results are formatted to the chosen number of decimals. Dose totals round to the nearest 1 mg.
| Field | Type | Min | Max | Step/Pattern | Error Text | Placeholder |
|---|---|---|---|---|---|---|
| Height value | number | 0 | — | — | — | — |
| Height unit | select | — | — | cm | m | in | — | — |
| Weight value | number | 0 | — | — | — | — |
| Weight unit | select | — | — | kg | lb | — | — |
| BSA cap | number | 0 | — | 0.01 | — | — |
| Dose per m² | number | 0 | — | 0.1 | — | — |
| Rounding (decimals) | range | 0 | 5 | 1 | — | — |
| Input | Accepted Families | Output | Encoding/Precision | Rounding |
|---|---|---|---|---|
| Height | cm, m, in | BSA | m² to 0–5 decimals | Selected decimal places |
| Weight | kg, lb | Mean and index | m² and % | Selected decimal places |
| Regimen | mg/m² | Total dose | mg integer | Nearest 1 mg |
| Table/JSON | Calculated values | CSV, JSON | Plain text | N/A |
Computation is browser based and deterministic for the same inputs. No personal data is transmitted or stored server side. Charts render locally using a client charting layer.
Calculations implement the Mosteller, Du Bois, Haycock, Gehan & George, and Boyd formulas commonly cited in clinical practice. The approach is empirical and intended for estimation.
No personal health information is stored or sent. Use only de identified inputs for demonstrations and training.
Body surface area estimation with dose conversion follows a simple sequence from measurements to interpretation.
Example: 170 cm and 65 kg with Mosteller gives about 1.752 m². With 120 mg/m², total ≈ 212 mg; with a 1.60 m² cap, total = 192 mg.
No. Calculations run in your browser and nothing is sent to a server. Copy and download actions operate on your device.
Avoid entering identifying information.It applies published formulas to your measurements. Differences between methods reflect their empirical origins and are usually small for typical adult sizes.
Choose the method your protocol specifies. If none is specified, use your service standard and review the index against the mean to understand variation.
It is the selected result compared with the mean of all methods, expressed as a percentage. Values near 100% indicate close agreement.
If the selected result exceeds the ceiling, the effective BSA equals the cap for dose conversion and display.
Height accepts centimetres, metres, or inches. Weight accepts kilograms or pounds. The engine converts units automatically before calculation.
Yes. Once loaded, calculations do not require a network connection. Charts and copies also work locally.
Yes. You can copy a table row, the full table as comma separated values, or a structured JSON payload of inputs and outputs.
Small percent differences between methods are expected. When close to a protocol threshold, follow the specified method and document the basis.