DocomintBody Surface Area Calculator
Calculate Body Surface Area (BSA) from height and weight using the Mosteller formula.
What is a Body Surface Area Calculator?
BSA is used clinically to dose certain medications (particularly chemotherapy) more precisely than a flat per-kilogram dose would — the Mosteller formula, a square root of height times weight over 3600, is the version most widely used in practice for its balance of simplicity and accuracy against more complex alternatives.
How to use the Body Surface Area Calculator
- Enter your height and weight
- Press Calculate
- Your body surface area, in square meters, appears instantly, computed on your device using the Mosteller formula
Formula
BSA = √((height(cm) × weight(kg)) ÷ 3600)
The Mosteller formula — valued clinically for combining reasonable accuracy with a much simpler calculation than alternatives like DuBois or Haycock.
Example
A person at 175cm and 70kg has a BSA of about 1.65 m² — a clinician would use this figure, not raw body weight alone, as an input to a per-m² medication dosing formula.
Common mistakes
- Confusing BSA with BMI — both use height and weight as inputs but measure genuinely different things (surface area vs. a weight-to-height-squared ratio).
- Using this result for actual medication dosing without a clinician's confirmation — that's a real medical decision, not just a calculator output.
- Entering height in meters instead of centimeters — the Mosteller formula as implemented here expects centimeters.
Frequently asked questions
What is Body Surface Area used for medically?
Clinicians use BSA to dose certain medications — most notably chemotherapy drugs — more precisely than a simple per-kilogram weight-based dose would, since BSA correlates better with metabolic processes relevant to drug distribution for some treatments.
How accurate is the Mosteller formula?
It's the most widely used BSA formula in clinical practice today, valued for its simplicity — a few other formulas (DuBois, Haycock) exist and produce slightly different results, but Mosteller's accuracy is considered comparable while being far easier to compute.
How is BSA different from BMI?
BSA estimates the total surface area of the body (in m²), used mainly for medication dosing. BMI estimates a weight category (Underweight/Normal/Overweight/Obese) from a weight-to-height-squared ratio. They use similar inputs but answer completely different questions.
Which BSA formula is more accurate, Mosteller or DuBois?
Both are considered comparably accurate in clinical practice — Mosteller is valued for its much simpler calculation, while DuBois (an older, more complex formula) is still used in some settings. The difference between the two for most body types is small.
Is my numbers uploaded anywhere?
No — Body Surface Area Calculator runs entirely in your browser using JavaScript/WebAssembly. Your numbers is never sent to a server.