Body surface area estimates outside body size
The Body Surface Area Calculator estimates BSA from height and weight. The local solver uses the Mosteller formula after converting imperial inputs into metric values when needed.
BSA is commonly used in medical and scientific contexts, but this page is an educational calculator, not a treatment tool.
Height and weight both affect the estimate
The Mosteller method uses the square root of height in centimeters multiplied by weight in kilograms divided by 3600. A change in either height or weight changes the final square-meter result.
The output is usually reported in square meters.
Imperial entries are converted first
If feet, inches, and pounds are entered, the calculator converts them to centimeters and kilograms before applying the formula. Unit mistakes can move the estimate enough to matter in comparisons.
Check whether inches are entered as extra inches beyond feet rather than total inches.
Mosteller is one common BSA formula
Several BSA formulas exist, and they can produce slightly different results. The local page identifies the method as Mosteller so users know which estimate they are reading.
When a clinical document requires a specific BSA method, use the method named in that document.
Medication dosing should not come from this page alone
Some medical dosing, chemotherapy calculations, kidney-indexed measures, or clinical protocols may involve BSA. Those decisions require healthcare professionals, current records, and the required formula.
Do not use a public calculator to choose or change medication dose.
BSA differs from BMI
BMI compares weight with height squared and is used as a screening ratio. BSA estimates body surface area. The two numbers answer different questions and should not be substituted for each other.
For a weight-height screening value, use the BMI Calculator.
Kidney results may use indexed area
Some kidney measures are indexed to a standard body surface area of 1.73 m2. That convention appears in many eGFR results. The GFR Calculator handles the kidney-function estimate separately.
Children need special care in clinical use
The formula can calculate a number from a child's height and weight, but pediatric medical use needs professional interpretation. Growth, dosing rules, and specialty protocols matter.
For any child-related clinical decision, use the healthcare team's calculation.
Body composition is not part of the formula
BSA uses height and weight only. It does not know body-fat percentage, muscle mass, hydration, or body shape. Two people with the same height and weight will produce the same BSA even if their composition differs.
Round only after the estimate is complete
Rounding height or weight before calculating can change the final BSA slightly. For comparison, use the most accurate available measurements and round the final result rather than the inputs.
Save the formula name with the number
A useful BSA note includes height, weight, unit system, formula name, result, and date. Without the method name, a later comparison with a different formula may look inconsistent.
Large weight changes should trigger recalculation
Because weight is part of the formula, a substantial weight change can move BSA. Height changes are less common in adults, but corrected height measurements can also change the estimate.
Use the result for understanding, not authority
This page can help someone understand what BSA means and how height and weight combine in the Mosteller method. It should not override lab systems, oncology protocols, transplant documents, or clinician calculations.
Clinical context decides whether BSA matters
Many everyday health questions do not need body surface area. If a form, report, or clinician specifically asks for BSA, then this estimate can help explain the number.
Otherwise, BMI, weight trend, lab values, or medical history may be more relevant than BSA.
Check source measurements before comparing results
A clinic height, home height, stated weight, and measured weight may not match exactly. Before comparing two BSA values, confirm that the source measurements were taken in a similar way.