What Is Your Body Surface Area?
What is your body surface area?
Body Surface Area (BSA) is the measured or calculated surface of a human body in square meters. Unlike body weight, which changes significantly with hydration, fat mass, and muscle mass, body surface area changes more slowly and correlates more reliably with many physiological parameters — including cardiac output, kidney function, and the distribution of certain drugs in the body. BSA is clinically essential for chemotherapy dosing, where many cytotoxic medications are dosed in mg/m² rather than mg/kg. It's also used in burn treatment (the "Rule of Nines" estimates percent of body surface burned), in calculating cardiac index (cardiac output / BSA), and in pediatric drug dosing. For adults, the average BSA is approximately 1.7 m² for females and 1.9 m² for males. Several validated formulas exist for BSA estimation, each calibrated to different populations. The DuBois formula (1916), though the oldest, remains widely used. The Mosteller formula (1987) is simpler to calculate and commonly used in pharmacy. The Haycock formula performs better for children. The Gehan-George formula was derived from a broader dataset. This calculator computes BSA using all four formulas and presents the consensus value — the most reliable approach for most clinical situations.
- →Calculating BSA for chemotherapy dose calculation (mg/m²)
- →Medical education and understanding clinical pharmacokinetics
- →Estimating cardiac index = cardiac output / BSA
- →Understanding body surface relative to metabolic and physiologic parameters
- →Calculating burn percentage when paired with body surface maps
Dr. Patel is preparing a chemotherapy regimen for a patient: female, 5'5", 145 lbs. DuBois formula: BSA = 0.007184 × (65.8 cm^0.725) × (65.8 kg^0.425) = 1.71 m². The planned drug dose is 75 mg/m². Dose = 75 × 1.71 = 128.25 mg, rounded to 130 mg per clinical protocol. The calculator runs all four formulas and shows the consensus BSA for verification.
Body Surface Area Calculator
5 Formulas · Drug Dosing · Rule of Nines · Sensitivity
Results update in real time as you adjust any input.
Common: 75 / 100 / 125 mg/m² · Sets your personal dose row in Dosing tab
About This Calculator
This body surface area calculator computes BSA using five validated clinical formulas simultaneously — DuBois & DuBois (1916), Mosteller (1987), Haycock (1978), Gehan & George (1970), and Boyd (1935) — and displays the consensus average as the primary result. Both imperial (ft/in/lbs) and metric (cm/kg) units are supported. All results update in real time as you adjust any input. Drug dosing can be calculated for any mg/m² dose, with a full comparison table across five standard dose levels.
The Formulas tab displays a bar chart of all 5 BSA formula results plus consensus, with DuBois highlighted in indigo (clinical standard) and a reference line at average male BSA (1.9 m²). A radar chart shows the BSA context profile across six dimensions. The Dosing tab shows a grouped bar chart comparing DuBois vs Consensus total dose across six prescription levels, with a line chart of BSA sensitivity to weight change at your height. The Rule of Nines tab renders a horizontal bar chart of percentage and area (m²) for each body region, plus Parkland formula calculations at four common TBSA burn percentages.
Dynamic accent colours reflect BSA category: amber (small, below 1.4 m²), indigo (below average, 1.4–1.7 m²), emerald (average range, 1.7–2.0 m²), orange (above average, 2.0–2.3 m²), red (large frame, above 2.3 m²). Formula variance (range across 5 formulas) is displayed prominently to communicate the inherent uncertainty in any BSA estimate. This calculator is for educational and planning purposes only — all clinical dosing decisions require verification by a licensed pharmacist or physician.
Results are estimates only and do not constitute medical advice. Consult a qualified healthcare professional before making health decisions.
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