Free Online Calculators
Health Tools
Everything you need to understand your body — completely free, no sign-up required.
From BMI to macros, we've got you covered.
BMI Calculator
Calculate your Body Mass Index instantly in metric (kg/cm) or imperial (lbs/ft) units. Get your BMI category, healthy weight range, and personalized insights.
BMR Calculator
Calculate your Basal Metabolic Rate — the calories your body burns at complete rest. Uses the gold-standard Mifflin-St Jeor equation for men and women.
TDEE Calculator
Find your Total Daily Energy Expenditure — how many calories you actually burn per day based on your activity level. Essential for any diet plan.
Calorie Calculator
Get your personalized daily calorie targets for weight loss, muscle gain, or maintenance. Based on your TDEE with goal-specific recommendations.
Ideal Weight Calculator
Calculate your ideal body weight range using three clinical formulas (Devine, Robinson, Miller) plus a BMI-based healthy weight range for your height.
Body Fat Calculator
Estimate your body fat percentage using the U.S. Navy method with neck, waist, hip, and height measurements. More informative than BMI alone.
Protein Calculator
Find your daily protein needs based on your weight and fitness goal — whether building muscle, losing fat, or maintaining health. Evidence-based recommendations.
Water Intake Calculator
Calculate your recommended daily water intake based on weight, activity level, and climate. Stay optimally hydrated for health and performance.
Macro Calculator
Get personalized daily targets for protein, carbohydrates, and fat in grams. Optimized for your calorie needs and fitness goal — fat loss, maintenance, or muscle gain.
Specialized
BMI Calculators by Category
Find the BMI calculator tailored to your specific situation.
BMI for Men
Muscle mass considerations
BMI for Women
Hormonal factors & body composition
BMI by Age
Age-specific healthy ranges
BMI for India
Asian BMI thresholds
BMI (kg & cm)
Metric unit calculation
BMI (lbs & ft)
Imperial unit calculation
Teen BMI
Ages 13–19, CDC percentiles
All Tools
Full calculator suite
Reference
Healthy Weight by Height
Find the healthy weight range for your specific height.
Why Use Our Tools
Free Health Calculators You Can Trust
Scientifically Accurate
Our calculators use clinically validated formulas: Mifflin-St Jeor for BMR/TDEE, WHO standards for BMI, U.S. Navy method for body fat, and Devine/Robinson formulas for ideal weight.
100% Free, No Sign-Up
Every calculator on BMIHero is permanently free. No registration, no subscription, no email required. Calculations run entirely in your browser — your data stays private.
Mobile-Friendly
All tools are fully responsive and work seamlessly on smartphones, tablets, and desktop computers. Get your results wherever you are.