Body Surface Area Calculator
Calculate your Body Surface Area (BSA) using five validated clinical formulas: Mosteller, DuBois, Haycock, Gehan & George, and Boyd.
Average adult male BSA ≈ 1.9 m²
Average adult female BSA ≈ 1.6 m²
Standard reference used in drug dosing: 1.73 m²
Calculate your Body Surface Area (BSA) using five validated clinical formulas — Mosteller, DuBois, Haycock, Gehan & George, and Boyd — commonly used in medicine for drug dosing.
How Body Surface Area Calculator Works
Mosteller's formula — BSA = √(height(cm) × weight(kg) ÷ 3600) — is the most widely used in clinical practice today because of its simplicity and solid accuracy across most adult body types. DuBois & DuBois (1916) is the historical original: 0.20247 × height(m)^0.725 × weight(kg)^0.425, still referenced as a long-standing benchmark.
Haycock's formula is generally preferred for pediatric patients, since it was derived specifically to perform well across a wide range of body sizes including infants and children, while Gehan & George is commonly cited in oncology for chemotherapy dosing calculations. Boyd's formula uses a more complex exponent that itself depends on weight, aiming for accuracy across an especially broad weight range.
Because BSA correlates more closely with metabolic rate and organ function than weight alone, it is the preferred basis for dosing certain medications (especially chemotherapy) where a fixed weight-based dose could be less precise across very different body sizes.
See It In Action
Who Uses Body Surface Area Calculator and Why
- Getting a general reference BSA figure using the same formulas referenced in some medical dosing contexts.
- Comparing your BSA across five different validated clinical formulas at once.
- Understanding how BSA differs from body weight as a way of scaling metabolic and physiological measures.
Mistakes to Avoid
- Using this calculator's result to determine your own or someone else's medication dose — BSA-based dosing must be calculated and verified by a licensed healthcare professional, since dosing errors can have serious consequences.
- Assuming the Haycock formula is interchangeable with adult-derived formulas like DuBois for a child — Haycock was specifically validated across pediatric body sizes where adult formulas are less accurate.
- Not noticing which formula a specific clinical context calls for — Gehan & George is commonly cited in oncology, for instance, while Mosteller is the general-purpose default in most clinical practice.
Tips for Best Results
- Mosteller is the most widely used formula in current clinical practice and is a reasonable default when you don't have a specific reason to prefer another.
- If you're comparing your BSA to a commonly cited average (like 1.9 m² for adult men), use the average of all five formulas rather than any single one for the most representative figure.
Fixing Common Problems
The five formulas gave slightly different BSA values. — A small spread between formulas is normal and expected, since each was derived independently — for reference purposes, the differences are usually minor; for anything clinical, always defer to a healthcare professional's calculation.
Terms Explained
BSA (Body Surface Area): An estimate of total external body surface, calculated from height and weight, used in medicine because it correlates more closely with metabolic rate and organ function than weight alone.