Health & Fitness
Free BMI, calorie, body fat and age calculators. Evidence-based tools using WHO and CDC formulas.
Health and fitness calculators take the guesswork out of understanding your body — using evidence-based formulas from the CDC, WHO, and peer-reviewed clinical literature to give you instant, accurate readings for BMI, calorie needs, body fat, and ideal weight. Every tool on CalkHub runs entirely in your browser, so your health data never leaves your device.
BMI Calculator — Body Mass Index
The BMI Calculator uses the standard CDC/WHO formula (weight ÷ height²) and returns your score alongside a colour-coded weight category (Underweight, Normal, Overweight, Obese), your healthy weight range for your exact height, and an optional waist circumference risk check. It supports both metric (kg/cm) and imperial (lbs/ft+in) units. BMI is a useful population-level screening tool — the calculator also explains its limitations, including why it overestimates risk for muscular individuals and may underestimate it for older adults.
Calorie & TDEE Calculator
The Calorie Calculator computes your Total Daily Energy Expenditure (TDEE) using the Mifflin-St Jeor equation — the formula recommended by the American Council on Exercise for its accuracy across most adult populations. Input your age, sex, weight, height, and activity level to receive your maintenance calorie target, plus adjusted targets for weight loss (−500 kcal/day = approx. 0.5 kg/week) and weight gain. Macronutrient breakdowns (protein, carbohydrates, fat) are included for each goal.
Age Calculator — Exact Chronological Age
The Age Calculator computes your exact age in years, months, days, hours, minutes, and seconds — updated in real time. It handles leap years, month-length differences, and timezone offsets correctly, making it accurate for government forms, medical assessments, school applications, and retirement planning. You can calculate age to any target date, past or future.
Why Use Online Health Calculators?
Online health calculators offer a key advantage over mobile apps or downloaded software: your data stays private. Every health tool on CalkHub runs entirely in your browser using JavaScript — your weight, age, and measurements are never sent to our servers, never stored in a database, and never shared with any third party. The formulas used are sourced from peer-reviewed clinical research (WHO, CDC, Mifflin-St Jeor) and are the same equations a doctor or dietitian would use. You get instant, accurate results without creating an account, installing software, or worrying about where your personal health data ends up.
Healthy BMI by Height — Quick Reference Table
| Height | Healthy Weight Range (BMI 18.5–24.9) |
|---|---|
| 5'0" (152 cm) | 94 – 127 lbs (42.6 – 57.6 kg) |
| 5'4" (163 cm) | 107 – 145 lbs (48.5 – 65.8 kg) |
| 5'8" (173 cm) | 121 – 163 lbs (54.9 – 73.9 kg) |
| 5'10" (178 cm) | 129 – 174 lbs (58.5 – 78.9 kg) |
| 6'0" (183 cm) | 136 – 184 lbs (61.7 – 83.5 kg) |
| 6'2" (188 cm) | 144 – 194 lbs (65.3 – 88.0 kg) |
Medical Disclaimer
All health calculators on CalkHub are for informational and educational purposes only. They use standard formulas designed for general adult populations and cannot account for individual medical history, medications, or clinical factors. Results are not a substitute for professional medical advice. Always consult a qualified healthcare provider before making health, diet, or fitness decisions.
BMI Calculator
Calculate BMI with CDC/WHO categories, healthy weight range for your height, waist circumference risk, and plain-language interpretation. Metric and imperial.
Calorie & TDEE Calculator
Calculate TDEE and calorie targets using Mifflin-St Jeor or Harris-Benedict. BMR, activity levels, and four goal targets for loss, maintenance, or muscle gain.
Ideal Body Weight Calculator
Calculate ideal body weight using Devine, Robinson, Miller, Hamwi formulas plus healthy BMI range. Instant, accurate results for men and women.