# What is my BSA (body surface area)?

Calculates body surface area (BSA) in square meters from height and weight with the Mosteller formula and the Du Bois formula.

- Page: https://www.acalculator.org/health/bsa-calculator
- JSON spec: https://www.acalculator.org/health/bsa-calculator.json
- Version: c3cb6988e704

## Default answer

Example with the default inputs (Height 5 ft 10 in, Weight 180 lb): The body surface area is 2.01 m² by the Mosteller formula and 2 m² by the Du Bois formula.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| height | Height | Height without shoes. |
| weight | Weight | Body weight. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| mosteller | BSA (Mosteller) | Body surface area by the Mosteller formula, in square meters, to 2 decimals. |
| dubois | BSA (Du Bois) | Body surface area by the Du Bois formula, in square meters, to 2 decimals. |

## Method

Mosteller: BSA (m²) = √(height in cm × weight in kg ÷ 3600). Du Bois: BSA (m²) = 0.007184 × weight^0.425 × height^0.725.

## Assumptions

- Height in centimeters and weight in kilograms; pounds and feet are converted exactly (1 lb = 0.45359237 kg, 1 in = 2.54 cm).
- Each area is rounded to 2 decimals, halves up.
- Both formulas estimate the skin area; neither was built for extreme body sizes.

## Worked examples

1. height = 1.7, weight = 70 gives mosteller = 1.82, dubois = 1.81. Source: Mosteller 1987: √(170 × 70 ÷ 3600) = 1.8181; Du Bois 1916: 0.007184 × 70^0.425 × 170^0.725 = 1.8097.
2. height = 1.778, weight = 81.646627 gives mosteller = 2.01, dubois = 2.
3. height = 1.1, weight = 18 gives mosteller = 0.74, dubois = 0.74.
4. height = 1.6, weight = 50 gives mosteller = 1.49, dubois = 1.5.

## FAQ

### What is body surface area?

Body surface area (BSA) is an estimate of the total area of the skin, in square meters (m²). An adult is usually between 1.6 and 2.0 m². Doctors use it to scale some drug doses, such as chemotherapy, and to index measures such as cardiac output and kidney function to body size.

### Which BSA formula is best?

The Mosteller formula is the most widely used because it is simple: the square root of height in cm times weight in kg, divided by 3,600. The Du Bois formula (1916) is the oldest. For most adults the two differ by less than 0.05 m². The formula your clinic uses is the one to follow.

### How do I calculate BSA by hand?

Multiply your height in centimeters by your weight in kilograms, divide by 3,600, and take the square root. For 170 cm and 70 kg: 170 × 70 = 11,900; 11,900 ÷ 3,600 = 3.306; √3.306 = 1.82 m².

### Can I use pounds and inches?

Yes. The calculator converts exactly: 1 inch is 2.54 cm and 1 pound is 0.45359237 kg. The formulas themselves use centimeters and kilograms.

## Sources

- Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987;317(17):1098. https://doi.org/10.1056/NEJM198710223171717
- Du Bois D, Du Bois EF. Clinical calorimetry: tenth paper. A formula to estimate the approximate surface area if height and weight be known. Arch Intern Med. 1916;XVII(6_2):863-871. https://doi.org/10.1001/archinte.1916.00080130010002
- National Institute of Standards and Technology. Guide for the Use of the International System of Units (SI), NIST Special Publication 811, Appendix B (1 lb = 0.45359237 kg, 1 in = 2.54 cm). https://www.nist.gov/pml/special-publication-811