BSA Calculator
Calculate your Body Surface Area using 8 medical formulas — Mosteller, Du Bois, Haycock and more.
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Our free BSA Calculator calculates your Body Surface Area using 8 clinically established formulas simultaneously — Du Bois, Mosteller, Haycock, Gehan & George, Boyd, Fujimoto, Takahira, and Schlich. Enter your weight and height in any unit and get all results in m², ft², and in² instantly. BMI is also calculated automatically.
How to Use This Calculator
1
Select your gender — required for the Schlich formula which uses separate male and female equations.
2
Enter your body weight and select your unit — pounds or kilograms.
3
Enter your height in cm, metres, or feet — or use the feet and inches fields below.
4
Click Calculate BSA to see all 8 formula results side by side in m², ft², and in².
5
Your BMI is calculated and displayed automatically at the bottom of the results.
8 BSA Formulas — Quick Reference
| Formula | Best Used For | Complexity |
|---|---|---|
| Mosteller | Clinical settings — simplest and most widely used today | Very Simple |
| Du Bois | General adults — most historically cited formula | Standard |
| Haycock | Children and infants — developed for pediatric patients | Standard |
| Gehan & George | General adult and pediatric use | Standard |
| Boyd | Extreme weight ranges — handles outliers well | Complex |
| Fujimoto | Asian populations — developed on Japanese subjects | Standard |
| Takahira | Japanese adult populations | Standard |
| Schlich | Gender-specific — separate male and female equations | Gender-Specific |
Frequently Asked Questions
For most adults the Mosteller formula is the recommended choice — it is the most widely used in modern clinical practice due to its simplicity and accuracy. For children and infants Haycock is preferred. For Asian populations Fujimoto is more appropriate. Our calculator shows all 8 formulas simultaneously so you can compare and use the most relevant one for your situation.
For most adults BSA falls between 1.6 m² and 2.0 m². The average adult male has a BSA of approximately 1.9 m² and the average adult female approximately 1.6 m². There is no ideal BSA value the way there is for BMI — BSA is used to normalize other clinical measurements rather than as a standalone health indicator.
Most chemotherapy drugs are dosed in milligrams per square metre of BSA (mg/m²). This approach accounts for differences in body size between patients and helps oncologists deliver the correct therapeutic dose. Using BSA rather than body weight alone reduces the risk of under-dosing (reducing treatment effectiveness) or over-dosing (increasing toxicity and side effects).
Each formula was developed on a different study population using a different mathematical approach. Formulas developed on specific ethnic groups or age groups may perform better for those populations. For most adults the differences between formulas are small — typically within 2 to 5 percent. Our calculator displays all 8 results so you can see the variation and choose the most appropriate formula.
Want to Understand BSA in Depth?
Read our complete guide — all 8 BSA formulas explained, medical uses including chemotherapy dosing, BSA vs BMI, and normal reference values by age.