Health & Fitness

Fitness Calculators

Calculate BMR, body fat percentage, daily calorie burn, BMI, water intake, and ideal weight instantly.Track your fitness journey — 100% free, no sign-up required

✓ Trusted by 100,000+ fitness enthusiasts✓ Used in 70+ countries✓ WHO & ACSM standard formulas✓ No data storage
💪 4+ fitness calculators available — all free, all accurate

Why Use Numrexo Fitness Calculators?

Our fitness calculators are designed for gym-goers, personal trainers, athletes, weight loss seekers, and anyone on a fitness journey. Each tool uses standard formulas from WHO (World Health Organization), ACSM (American College of Sports Medicine), and leading fitness research.

The BMR Calculator (Basal Metabolic Rate) tells you how many calories your body burns at complete rest. This is your foundation for weight loss or muscle gain — eat below BMR to lose weight, above to gain.

Our Body Fat Calculator uses the US Navy Method (based on circumference measurements) to estimate your body fat percentage. Unlike BMI, body fat percentage gives you a true picture of your body composition.

The Calorie Burn Calculator estimates calories burned during various activities — walking, running, cycling, swimming, weight training, and more. Perfect for tracking workout effectiveness.

Our BMI Calculator follows WHO standards to assess weight categories (underweight, normal, overweight, obese). The Water Intake Calculator recommends daily hydration based on weight, activity level, and climate. The Ideal Weight Calculator gives you healthy weight ranges based on height and body frame.

100% free, no registration, no data collection. All calculations happen in your browser — your health data stays private.

Popular Fitness Calculations

  • BMR Calculator: Basal metabolic rate for calorie planning
  • Body Fat Percentage: US Navy Method — accurate body composition
  • Calorie Burn: Calories burned during 50+ activities
  • BMI Calculator: Body Mass Index per WHO standards
  • Water Intake: Daily hydration needs based on lifestyle
  • Ideal Weight: Healthy weight range for your height
  • Calorie Deficit: How many calories to cut for weight loss
  • Macro Calculator: Protein, carbs, fats for your goals

Scientific Standards Used

Mifflin-St Jeor (BMR)Harris-Benedict (BMR)US Navy Method (Body Fat)WHO BMI ClassificationACSM Activity Multipliers

💡 Pro Tip: Calculate your BMR first, then multiply by your activity level (sedentary to very active) to get your TDEE (Total Daily Energy Expenditure). For weight loss, eat 300-500 calories below TDEE. For muscle gain, eat 300-500 above.

Disclaimer: These calculators provide estimates based on standard formulas. Individual results may vary. Consult a doctor or certified trainer before starting any fitness or nutrition program.

Related:All Calculators •Health Calculators •Nutrition Tools

🏋️ ACSM & WHO standard formulas | Results are estimates — listen to your body