8 Tools

Health Calculators

Evidence-based body composition and nutritional calculators used by clinicians, nutritionists, and patients worldwide. All support metric and imperial units, real-time results, visual outputs, and PDF/CSV export — no login required.

WHO-based formulas Instant results PDF & CSV export No data stored

⚖️

BMI Calculator

Body Mass Index with WHO classification, visual gauge, ideal weight range, BMI Prime, Ponderal Index, and PDF/CSV export. Metric and imperial.

🔥 Most Used Use tool

🔥

BMR / TDEE Calculator

Basal metabolic rate and total daily energy expenditure using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas side by side with activity multiplier.

🔥 Popular Use tool

📐

BSA Calculator

Body Surface Area using Mosteller, DuBois & DuBois, Haycock, and Gehan-George formulas. Used for chemotherapy dosing, cardiac index, and renal drug adjustment.

Clinical Use tool

🎯

Ideal Weight Calculator

Compare five ideal body weight formulas simultaneously: Devine, Robinson, Miller, Hamwi, and Peterson — with range visualisation and notes on when to use each.

🔥 Popular Use tool

🍽️

Caloric Needs Calculator

Daily caloric requirements by activity level with macronutrient breakdown. Supports weight loss, maintenance, and muscle-gain goals with calorie deficit/surplus guidance.

✨ New Use tool

📏

Waist-Hip Ratio

Cardiovascular and metabolic risk using WHO waist-to-hip thresholds. A stronger predictor of visceral adiposity and disease risk than BMI alone.

🔥 Popular Use tool

💪

Body Fat Percentage

Estimate body fat using the U.S. Navy circumference method and BMI-based formula. Outputs fat mass, lean mass, and fitness category with visual chart.

No tools match this filter.

📐

Multiple Formulas, One Screen

Where competitors show one result, we show all validated formulas side by side so you choose the most clinically appropriate one.

🔄

Live Metric ↔ Imperial Toggle

Switch units mid-calculation without re-entering data. All outputs update instantly in your chosen measurement system.

📄

Branded PDF Report

Every calculator generates a professional, printable PDF — ideal for patient handouts or including in clinical notes.

About Health & Body Composition Calculators

Health calculators translate raw measurements — weight, height, waist circumference — into standardised indices that guide clinical decisions and patient counselling. Used daily by GPs, dietitians, endocrinologists, and fitness professionals, these tools provide a quick, objective starting point for health assessment.

Which Formula Should I Use?

Different tools suit different contexts. For population screening and general practice, BMI remains the standard despite its limitations with muscular individuals. For drug dosing in oncology and critical care, BSA (Mosteller formula) is preferred. For nutritional planning, BMR using the Mifflin-St Jeor equation is the most accurate for most non-athletic adults. Our tools display multiple formulas simultaneously so clinicians can make an informed choice.

Metric vs. Imperial Units

All calculators support seamless switching between metric (kg, cm) and imperial (lbs, ft/in) units. Conversion uses exact NIST-defined factors rather than rounded approximations — ensuring accuracy to the decimal place regardless of which system you enter.

Limitations of Body Composition Calculators

Anthropometric calculators are screening tools, not diagnostic instruments. BMI does not distinguish between fat and muscle mass and is less accurate in elderly patients, athletes, and certain ethnic groups. Results should always be interpreted alongside a full clinical assessment by a qualified healthcare professional.

Formula Reference

Tool	Primary Formula	Clinical Use	Source
BMI	weight (kg) ÷ height² (m²)	Obesity screening	WHO, 2000
BMR	Mifflin-St Jeor (1990)	Caloric planning, nutritional support	JAMA, 1990
BSA	Mosteller (1987)	Chemotherapy dosing, cardiac index	NEJM, 1987
Ideal Weight	Devine (1974) / Robinson (1983)	Drug dosing reference weight	Multiple sources
Waist-Hip Ratio	Waist ÷ Hip circumference	CVD and metabolic risk	WHO Report, 2008

Frequently Asked Questions

What is the difference between BMI and body fat percentage?+

BMI is a proxy calculated from height and weight alone — it does not directly measure fat. Body fat percentage is a more precise measure of adiposity but requires additional measurements such as skinfolds, circumferences, or DEXA scanning. A person can have a normal BMI but high body fat (normal-weight obesity), particularly common in sedentary older adults.

Which BMR formula is most accurate?+

The Mifflin-St Jeor equation (1990) is considered most accurate for most non-obese adults, validated against indirect calorimetry in multiple studies. The Harris-Benedict equation (revised 1984) is older but widely used. The Katch-McArdle formula is most accurate when lean body mass is known (e.g. from DEXA). Our BMR tool shows all three simultaneously.

Are these calculators suitable for children?+

Most calculators here are validated for adults (18+). BMI in children uses age- and sex-specific percentile charts rather than fixed cut-offs. For paediatric tools, visit our Pediatrics category which includes WHO growth chart percentiles and a paediatric dose calculator.

Do these tools store my personal data?+

No. All calculations run entirely within your browser using JavaScript. No data is transmitted to any server, stored in any database, or shared with any third party. You can verify this by using the tools while offline after the page loads.

Can I export my results?+

Yes. Every tool offers PDF download, CSV export, and browser print. The PDF report is professionally formatted, includes a medical disclaimer, and is suitable for patient records or handouts.

Related Tools on MediCalc Pro

For cardiovascular risk see the Framingham Risk Score. For drug dosing based on body weight or BSA see the Weight-Based Dose Calculator. For renal function and dosing adjustment see Creatinine Clearance (CrCl). For paediatric growth assessment see Growth Chart Percentile.

⚠️ Medical Disclaimer: All calculators are for educational and informational purposes only. They are not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional before making health decisions.