Free Health & Fitness Calculators
Track calories, plan macros, estimate body fat, find your heart rate zones, and more — all free, private, and instant.
🏋️ 9 calculators • 6 guidesNutrition & Diet
Calorie Calculator
Calculate your BMR and daily calorie needs (TDEE) based on age, gender, height, weight, and activity level.
Macro Calculator
Get your daily protein, carbs, and fat targets based on your calorie goals and diet preferences.
Water Intake Calculator
Find out how much water you should drink daily based on weight, activity level, and climate.
Calorie Burn Calculator
Estimate calories burned during 100+ activities — running, walking, swimming, cycling, yoga, and more.
Body & Fitness
Body Fat Calculator
Estimate your body fat percentage using the US Navy method — just waist, neck, and height measurements.
Ideal Weight Calculator
Find your ideal body weight using 4 validated formulas: Devine, Robinson, Miller, and Hamwi.
Heart Rate Zone Calculator
Calculate your 5 training heart rate zones for fat burning, cardio, and peak performance workouts.
Pregnancy Due Date Calculator
Estimate your due date from your last menstrual period, with trimester timeline and key milestones.
Sleep Calculator
Find the best bedtime or wake-up time based on 90-minute sleep cycles for optimal rest and energy.
Learn & Understand
Nutrition & Calorie Guide
Everything about calories, TDEE, macronutrients, and building a sustainable nutrition plan.
Fitness & Exercise Guide
Heart rate zones, MET values, workout planning, and the 80/20 training principle explained.
Body Composition Guide
Body fat percentage, ideal weight formulas, BMI limitations, and how to improve body composition.
Why Use Health Calculators?
Understanding your body's numbers helps you make informed decisions about nutrition, exercise, and wellness. Our calculators use medically validated formulas to give you personalized insights:
- Personalized nutrition — Know exactly how many calories and macros your body needs
- Smarter workouts — Train in the right heart rate zone for your fitness goals
- Track progress — Monitor body composition changes over time
- Stay hydrated — Get a science-based daily water target
- 100% private — All calculations run in your browser, no data sent anywhere
About Our Formulas
We use peer-reviewed, clinically validated equations: the Mifflin-St Jeor equation for BMR (recognized as the most accurate by the American Dietetic Association), the US Navy body fat formula, the Karvonen formula for heart rate zones, and MET-based calculations from the Compendium of Physical Activities for calorie burn estimates.
Health & Fitness Tips
Start with Your TDEE
Your Total Daily Energy Expenditure (TDEE) is the foundation of any diet plan. Use our Calorie Calculator to find your TDEE, then adjust based on your goal: subtract 500 calories/day to lose ~1 lb/week, or add 300-500 to build muscle.
Protein Is Key
Whether you're losing fat or building muscle, protein is essential. The Macro Calculator helps you find the right protein-carb-fat balance for your specific goals. Most active adults need 0.7-1g of protein per pound of body weight.
Don't Forget Hydration
Even mild dehydration can reduce exercise performance by 10-20%. Use the Water Intake Calculator to get your personalized daily target based on your weight and activity level.
Train Smarter, Not Harder
Heart rate zone training ensures you're exercising at the right intensity. Zone 2 (60-70% max HR) burns fat efficiently, while Zone 4-5 builds peak fitness. Use the Heart Rate Zone Calculator to find your personal zones.