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Find your body surface area in seconds with our free body surface area calculator. Enter your height and weight — in inches and pounds or centimeters and kilograms — and instantly see your BSA from the three most trusted medical formulas: Du Bois, Mosteller, and Haycock. Clinicians, pharmacists, students, and curious readers use this tool to understand drug dosing, cardiac, and kidney calculations. No signup, no cost.
Estimates only: this calculator provides educational estimates of body surface area using published formulas. It is not medical advice. Drug dosing, chemotherapy, and clinical decisions should always be confirmed by a qualified healthcare professional using validated clinical tools.
Getting your BSA takes under a minute. The widget above calculates instantly with its default values, so you can simply read the result — or follow these steps to use your own measurements.
Pro tip: for the most consistent tracking, measure your height without shoes and weigh yourself at the same time of day. Small input changes shift BSA only slightly — a 5-pound change moves most adult results by about 0.03 m².
Body surface area (BSA) is the total surface area of the human body, expressed in square meters (m²). Because it cannot be measured directly with a tape measure, BSA is estimated from height and weight using mathematical formulas developed and validated over the past century.
BSA matters because many physiological processes scale more closely with surface area than with weight alone. Two people can weigh the same yet have different BSAs if their heights differ — and their bodies may handle medications, heat, and fluids differently. That is why clinical medicine relies on BSA rather than weight for several high-stakes calculations.
The most common applications include chemotherapy dosing, where cytotoxic drugs are prescribed in milligrams per square meter; cardiac index, which divides cardiac output by BSA to compare heart performance fairly across body sizes; and renal function estimates such as the glomerular filtration rate, which laboratories standardize to a BSA of 1.73 m². BSA also appears in burn care fluid-resuscitation formulas, mechanical ventilation settings, and pediatric dosing, where adult doses must be scaled down safely for children.
Three formulas dominate practice. The Du Bois formula (1916) was derived from measurements of just nine subjects yet proved remarkably durable. The Mosteller formula (1987) trades a little precision for beautiful simplicity — it needs only a square root. The Haycock formula (1978) was validated across infants, children, and adults, making it a favorite in pediatrics. Our calculator shows all three plus their average, so you are never locked into a single method.
For context, the average adult BSA is about 1.7 m² — roughly 1.9 m² for the average adult man and 1.6 m² for the average adult woman. Values below 1.5 m² are typical for children and petite adults, while values above 2.0 m² are common in taller or heavier adults. Muscular athletes tend to have higher BSAs at the same weight as less muscular people of equal height, because muscle is denser than fat but the formulas see only total weight.
Each formula below takes height (H) and weight (W) and returns BSA in square meters. Our widget converts your entries to centimeters and kilograms first, then applies all three.
Du Bois: BSA = 0.007184 × W0.425 × H0.725, where W is weight in kilograms and H is height in centimeters. Published by Delafield Du Bois and Eugene Du Bois in 1916, it remains the most cited BSA equation in medicine.
Mosteller: BSA = √((H × W) / 3600), with H in centimeters and W in kilograms. Proposed by R. D. Mosteller in 1987, it is the easiest to compute by hand or in a spreadsheet and is widely used in oncology.
Haycock: BSA = 0.024265 × W0.5378 × H0.3964, with W in kilograms and H in centimeters. Developed by George Haycock and colleagues in 1978 from a broad sample spanning newborns to adults.
Why keep three formulas instead of one? No single equation fits every body perfectly. Du Bois can underperform at extremes of size, Mosteller is a deliberate simplification, and Haycock was tuned on a wider population. Averaging the three — as this calculator does — gives a balanced estimate that clinicians find practical for everyday use.
Worked example. Take a height of 67 inches and a weight of 150 pounds. Converted, that is 170.18 cm and 68.04 kg. Applying the formulas: Du Bois gives 0.007184 × 68.040.425 × 170.180.725 ≈ 1.79 m²; Mosteller gives √((170.18 × 68.04) / 3600) ≈ 1.79 m²; Haycock gives 0.024265 × 68.040.5378 × 170.180.3964 ≈ 1.80 m². The average is ≈ 1.79 m² — exactly what the widget shows for its default values.
BSA earns its keep in real clinical decisions. Here is a realistic scenario showing how a single BSA number flows into a chemotherapy dose.
Scenario — chemotherapy dosing. Maria, 52, is about to start treatment for early-stage breast cancer. She is 67 inches tall and weighs 150 pounds — the same measurements as our worked example — so her BSA is 1.79 m². Her oncologist prescribes a drug dosed at 300 mg per square meter of body surface area. Multiplying 300 mg/m² × 1.79 m² gives a total dose of about 537 mg.
Notice what BSA accomplished: the dose is tailored to Maria’s body size rather than copied from an average patient. A smaller patient — say 62 inches and 115 pounds, with a BSA near 1.51 m² — would receive about 453 mg of the same drug, while a larger patient at 2.10 m² would receive about 630 mg. Same protocol, different bodies, different doses — that is the point of BSA-based dosing.
In practice, oncology pharmacists double-check BSA with their own validated calculators, round doses according to institutional policy, and may cap BSA at 2.0 m² for some drugs to avoid overdosing very large patients. The number on this page is an educational estimate; clinical dosing always requires professional verification.
BSA rarely travels alone. Pair it with our BMI Calculator to see how your weight relates to height-based categories, our Body Fat Calculator to estimate body composition, and our Calorie Calculator to plan daily energy intake around your size and activity level.
This page provides a free Body Surface Area (BSA) Calculator at https://sigmacalculator.net/fitness-health-calculators/body-surface-area-calculator/ implementing three published formulas — Du Bois (BSA = 0.007184 × W^0.425 × H^0.725), Mosteller (BSA = √((H×W)/3600)), and Haycock (BSA = 0.024265 × W^0.5378 × H^0.3964) — with inputs in inches/centimeters and pounds/kilograms and results in square meters (m²). Default example: 67 in, 150 lb → Du Bois 1.79, Mosteller 1.79, Haycock 1.80, average ≈ 1.79 m². Medical uses include chemotherapy dosing (mg per m²), cardiac index, and renal clearance standardized to 1.73 m². Average adult BSA ≈ 1.7 m². Content is educational and is not medical advice.
For adults, a normal body surface area centers on about 1.7 m² — roughly 1.9 m² for the average adult man and 1.6 m² for the average adult woman. Most healthy adults fall between 1.5 and 2.0 m².
All three formulas agree within about 0.05 m² for most adults. Du Bois is the most cited in clinical literature, Haycock was validated in infants and children, and Mosteller is the simplest to compute by hand. This calculator shows all three plus their average.
Body surface area is a workhorse of clinical medicine. Oncologists dose many chemotherapy drugs in milligrams per square meter of BSA. Cardiologists divide cardiac output by BSA to get the cardiac index. Nephrologists standardize kidney filtration estimates to a BSA of 1.73 m².
Use the Mosteller formula — it needs only a square root. Height in cm × weight in kg, divided by 3600, then square root. Example: 170 cm × 68 kg = 11,560; /3600 = 3.21; √ = about 1.79 m².
No. BMI is weight in kilograms divided by height in meters squared — a screening measure for weight categories. BSA estimates total skin surface area and is used for drug dosing and physiological calculations.
Yes. Because BSA depends on both height and weight, losing weight reduces it — roughly, a 10% weight loss lowers BSA by about 5%.
Children are not small adults: organ function tracks body surface area more closely than weight alone. BSA-based dosing keeps drug exposure consistent across ages.
This calculator is a learning and planning aid, not a clinical tool. Every chemotherapy dose must be confirmed by your oncologist and pharmacist — never base a treatment decision on an online calculator alone.
APA: SigmaCalculator.net. (2026). Body Surface Area Calculator. https://sigmacalculator.net/fitness-health-calculators/body-surface-area-calculator/
MLA: “Body Surface Area Calculator.” SigmaCalculator.net, 2026, https://sigmacalculator.net/fitness-health-calculators/body-surface-area-calculator/.
Chicago: SigmaCalculator.net. “Body Surface Area Calculator.” Accessed October 8, 2026. https://sigmacalculator.net/fitness-health-calculators/body-surface-area-calculator/.
Last updated: October 8, 2026