Body Composition Calculators
Body composition calculators for BMI, body surface area (BSA), ideal body weight (IBW), and lean body weight (LBW) — with formulas and worked examples.
BMI Calculator
Calculate Body Mass Index and weight classification
Body Surface Area (BSA)
Calculate BSA using Mosteller, DuBois, and other formulas
Ideal Body Weight (IBW)
Calculate ideal body weight using Devine formula
Adjusted Body Weight
Calculate adjusted body weight for dosing in obese patients
How Body Composition Calculations Work
Body composition calculators estimate size and weight metrics used in clinical documentation and dose-related contexts (for example, BSA for chemotherapy). These tools provide standardized references for clinical practice.
The usual inputs are height, weight, and sometimes sex. These are estimates and should be interpreted clinically. Always confirm height and weight units before calculating.
Common Body Composition Calculations Explained
Body Mass Index (BMI)
BMI relates weight to height and is used as a quick screening metric. It does not directly measure body fat.
Example question:
A person weighs 80 kg and is 1.75 m tall. What is the BMI?
Worked example:
Result: Answer: BMI ≈ 26.1
Tip: Use metres for height, then square it.
Body Surface Area (BSA)
BSA estimates body size using height and weight. It is commonly used in oncology and some medication dosing calculations.
Example question:
A patient is 170 cm tall and weighs 70 kg. What is BSA (Mosteller)?
Worked example:
Result: Answer: BSA ≈ 1.82 m²
Tip: Mosteller is: multiply → divide → square root.
Ideal Body Weight (IBW)
IBW is an estimate based mainly on height (and sex in common formulas). It's often used as a reference value in clinical calculations.
Example question:
A person is 180 cm tall. Estimate IBW using a simple height-based method.
Worked example:
Result: Answer: IBW ≈ 71.3 kg
Tip: This method uses BMI 22 as a reference.
When These Calculators Are Used
- •Recording BMI and basic health metrics
- •Calculating BSA for dose-related calculations (where applicable)
- •Estimating IBW/LBW as reference values in clinical settings
- •Cross-checking weight/height units before using dose calculators
- •Education, study, and quick bedside checks
Clinical safety note:
These calculations are estimates and must be interpreted clinically. Always confirm height/weight units and follow local protocols where values affect care decisions. Examples on this page are for calculation practice only.
Related Calculator Categories
Frequently Asked Questions
Clinical reminder: Always follow local protocols and consult medication information sheets. These examples are for calculation practice only.