HesapHanem

Body Surface Area (BSA) Calculator

What is my body surface area?

How it is calculated

Body surface area (BSA) estimates the skin area of the body in square metres. The tool shows two classic formulas side by side. Mosteller: BSA = √(height × weight / 3600), with height in centimetres and weight in kilograms. Du Bois: BSA = 0.007184 × height0.725 × weight0.425, with the same units. Both results are rounded to two decimals and shown in m². Height and weight must be above zero. The two formulas usually agree within a few hundredths of a square metre for adults of average build; they can drift apart for very small or very large bodies. BSA is a population estimate, not a measurement of one person.

Worked example

Take a height of 175 cm and a weight of 70 kg. Mosteller: 175 × 70 = 12,250; divided by 3,600 this is 3.4028, and its square root is 1.84 m². Du Bois: 1750.725 ≈ 42.2 and 700.425 ≈ 6.08; multiplied by 0.007184 this gives 1.85 m². The two methods differ by only about 0.01 m² for this body size.

Try this example →

Common mistakes

  • Entering height in metres (1.75) or feet and inches; both formulas expect centimetres.
  • Entering weight in pounds instead of kilograms, which inflates the area by more than 2 times.
  • Swapping the two fields, which changes the Du Bois result because the exponents differ for height and weight.
  • Mixing the two formulas: a dose or reference range quoted for one formula should be compared with that formula's value.
  • Using the figure as a clinical dose on its own; it is only an estimate and any medical dosing must follow the prescriber's instructions.

Sources

About this calculator

This calculator estimates body surface area (BSA) — the total external area of the human body, expressed in square meters — from height and weight, using the Mosteller and Du Bois formulas, two widely validated methods that give closely matching results for most adults.

BSA matters most in clinical medicine: it is the standard way doctors and pharmacists scale chemotherapy drug dosing and certain other medications, since dosing by body weight alone can be less accurate for drugs that act on tissue surface. It is also used in burn-injury assessment and some physiological and cardiac index calculations.

Was this helpful?

You can pick up to 3 reactions.

Comments (1)

  • Editorial team

    The two formulas are close but not identical: for 170 cm and 70 kg Mosteller gives 1.82 m² and Du Bois 1.81 m². Height goes in centimetres and weight in kilograms. Body surface area is used in medicine to scale some doses, but those calculations follow the care team's own protocol and rounding rules, so use this figure to understand the number, not to work out a dose. Which of the two formulas does your source use?

Popular calculators

Loan Calculator

Monthly payment, total interest and full amortization schedule.

Percentage Calculator

Percent change, percent of, and ratio calculations.

Discount Calculator

Calculate final price, savings, and discount amount.

BMI Calculator

Body mass index from height and weight (metric or imperial).

Age Calculator

Compute your exact age in years, months and days from a birth date.

Compound Interest Calculator

Calculate the final amount and interest earned with compounding.

All Calculators