Body Surface Area (BSA) Calculator
Enter your height and weight to estimate body surface area using common medical formulas.
What is a body area surface calculator?
A body area surface calculator estimates your Body Surface Area (BSA), which is the total external area of your body measured in square meters (m²). In healthcare, BSA is often used instead of body weight alone for medication dosing, especially for chemotherapy, pediatric medications, and fluid management in some clinical settings.
When people search for a body area surface calculator, they usually want a quick and reliable way to estimate BSA from height and weight. That is exactly what this tool does.
How this calculator works
This calculator accepts either metric or imperial units and converts everything internally to centimeters and kilograms before calculating BSA. It then shows four widely used formulas:
- Mosteller – simple and commonly used in clinical settings.
- Du Bois & Du Bois – one of the oldest historical formulas.
- Haycock – often considered useful for pediatric applications.
- Gehan & George – another validated approach for estimating BSA.
Because formulas are mathematical models, values can differ slightly. Small differences are normal and expected.
Why Body Surface Area matters
1) Medication dosing
Some medications are dosed per square meter (mg/m²) because metabolism and distribution may correlate better with body surface area than with body weight alone.
2) Clinical assessment
BSA appears in medical calculations for cardiac index, renal function interpretations, and burn management frameworks.
3) Pediatric and oncology care
In children and cancer care, precision matters. A small difference in dose can have meaningful effects, so clinicians often incorporate BSA into treatment planning.
Common BSA formulas explained
Mosteller Formula
BSA = √[(height in cm × weight in kg) / 3600]
This is the most straightforward equation and is frequently used because it is easy to compute and generally accurate for everyday clinical use.
Du Bois & Du Bois Formula
BSA = 0.007184 × height(cm)0.725 × weight(kg)0.425
This classic formula was published in 1916 and remains in many medical references.
Haycock Formula
BSA = 0.024265 × height(cm)0.3964 × weight(kg)0.5378
Haycock is often discussed in pediatric contexts and tends to perform well across varying body sizes.
Gehan & George Formula
BSA = 0.0235 × height(cm)0.42246 × weight(kg)0.51456
This equation is another validated approach and can be useful for comparison when precision is important.
How to use this body area surface calculator correctly
- Select your unit system (metric or imperial).
- Enter accurate height and weight values.
- Click Calculate BSA.
- Review results from multiple formulas.
- Use the value recommended by your clinician or protocol.
Important limitations
BSA calculations are estimates, not direct measurements. They do not capture full differences in body composition, hydration, edema, or disease state. That means two people with similar BSA may still have different metabolic responses.
For medical decisions, always follow guidance from a licensed healthcare professional. Online calculators are educational tools and should not replace clinical judgment.
Quick FAQ
Is BSA the same as BMI?
No. BMI estimates body mass relative to height and is often used for population-level weight categories. BSA estimates body surface area and is commonly used in medical dosing and clinical calculations.
Which formula should I choose?
Mosteller is commonly used in practice because of its simplicity. However, your healthcare team may follow a specific guideline or institutional protocol using a different formula.
Can I use this for children?
Yes, but pediatric dosing should always be reviewed by a qualified clinician. This calculator provides estimates only.
Final thoughts
A good body area surface calculator gives fast, transparent estimates and helps you understand how BSA is derived. This page provides multiple equations so you can compare outputs and discuss them confidently with your healthcare provider.