Estimate your body surface area (BSA) using Mosteller, Du Bois, Haycock, and other clinical formulas in metric or imperial units.
Quickly evaluate standard metabolic demographics and sizing indices:
Enter your weight and stature dimensions to compute multi-formula clinical Body Surface Area indexes.
The Mosteller formula is the simplest and most widely used method for estimating Body Surface Area, a measurement used clinically for drug dosing (especially chemotherapy) and for...
How different medical formulas calculate Body Surface Area based on weight and stature parameters.
| Formula Name | Mathematical Equation | Computed Result | Clinical Relevance & Context |
|---|---|---|---|
| Mosteller | BSA = √((Height in cm × Weight in kg) / 3600) | - | Published in 1987. Simple and easy to calculate. Now the most widely used formula in medicine. |
| Du Bois & Du Bois | BSA = 0.007184 × Height_cm^0.725 × Weight_kg^0.425 | - | Published in 1916. The historical standard model. Widely referenced in physiological and eGFR indices. |
| Haycock | BSA = 0.024265 × Height_cm^0.3964 × Weight_kg^0.5378 | - | Published in 1978. Preferred for pediatric calculations. Highly accurate for low birthweight newborns. |
| Gehan & George | BSA = 0.0235 × Height_cm^0.42246 × Weight_kg^0.51456 | - | Published in 1970. Provides a robust fit for populations with extreme heights and weights. |
| Boyd | BSA = 0.0003207 × Height_cm^0.3 × Weight_grams^(0.7285 - 0.0188 × log10(Weight_grams)) | - | Published in 1935. Highly complex formula that includes a logarithmic weight scaling term, ideal for pediatric and growth indexing. |
Why surface area index metrics are vital in medical assessments, renal clearances, and pharmacology.
In pharmacology, narrow-therapeutic-index medications (such as chemotherapy agents, immunotherapeutic drugs, and specific IV therapies) are dosed according to body surface area rather than body weight. This is because body water volume, blood volume, liver clearance pathways, and cardiac output correlate much more closely with BSA. Weight-only dosing can result in dangerous toxicity in obese patients or sub-therapeutic levels in extremely lean patients.
Glomerular Filtration Rate (GFR)—the primary measure of kidney health and filtration function—is standardly indexed to a standardized body surface area of **1.73 m²** (the normal average adult BSA). By dividing a patient's raw GFR values by their relative BSA index ratio, clinicians can directly compare kidney filtration capabilities across patients of widely differing body types.
The raw cardiac output (volume of blood pumped by the heart per minute) varies heavily based on body size. In intensive care medicine, doctors calculate the **Cardiac Index** by dividing cardiac output by the patient's BSA. A healthy Cardiac Index range is standardly 2.5 to 4.0 L/min/m². This adjusts outputs to body demands, allowing clinicians to diagnose heart failure or shock accurately regardless of patient height or mass.
The Mosteller formula, BSA (m²) = sqrt((height in cm x weight in kg) / 3600), is the simplest and most widely used in modern practice. The older Du Bois and Du Bois formula, BSA = 0.007184 x height^0.725 x weight^0.425, dates to 1916 and was derived from just nine study subjects.
The calculator also computes the Haycock formula (validated for use in children and infants), the Gehan and George formula, and the Boyd formula, which uses a more complex weight-based exponent. All five formulas typically agree within 1-2% of each other for a given height and weight, and the calculator also displays their average.
For a person who is 170 cm tall and weighs 70 kg, the Mosteller formula gives sqrt((170 x 70) / 3600) = sqrt(3.31), or about 1.82 m², closely matching the results from the other four formulas for the same measurements.
Because BSA correlates more closely with metabolic rate and cardiac output than body weight alone, it is used to standardize medication dosing, particularly for chemotherapy. For general fitness context rather than clinical dosing, pair this with the BMI Calculator or Ideal Weight Calculator.
Quick answers about how this tool works.
Chemotherapy drugs often have a very narrow therapeutic index, meaning the difference between an effective dose and a toxic dose is small. Dosing based on BSA helps standardize the concentration of the drug in the body, accounting for differences in blood volume and metabolic rates between individuals of varying heights and weights.
The Mosteller formula is the most popular due to its simplicity, while the Du Bois formula is the oldest and most historically standard. The Boyd formula is highly complex but preferred in pediatrics. Generally, all five formulas produce results within 1-2% of each other, and the average of these formulas is often used to minimize outliers.
The average BSA for an adult male is approximately 1.9 m², and for an adult female, it is approximately 1.6 m². The standard reference BSA used for indexing physiological parameters (like glomerular filtration rate or eGFR) is 1.73 m².
BSA formulas are mathematical models based on height and weight. They do not account for fluid retention (edema), severe dehydration, or body fat distribution. For extremely obese patients, some clinical guidelines recommend using an adjusted body weight rather than actual body weight in the equations.
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