Free Health & Fitness Calculators
Know your numbers. Enter your height, weight, age and training stats to instantly find your BMI, body fat, daily calorie needs, macros, one rep max and training zones. Every calculator is free, runs right in your browser, and takes less than a minute.
Body & Weight
Your BMI score and category, plus the healthy weight range for your height.
Estimate your body fat percentage from simple tape measurements.
Your ideal weight range from four trusted medical formulas.
How much water you should drink per day based on your weight and activity.
Calories & Nutrition
The calories your body burns at complete rest, from the Mifflin-St Jeor equation.
Your total daily calorie burn, with targets for losing, maintaining or gaining.
Daily calories to lose, maintain or gain weight at your chosen pace.
Turn your daily calories into protein, carb and fat gram targets for your goal.
Grams of protein per day for your body weight and activity level.
Training & Performance
Your estimated one rep max from four proven formulas, plus training loads.
Pace per mile or kilometer and finish times for common race distances.
Your five training zones with target beats per minute for each.
Why Use These Calculators?
Every training plan, diet and fitness goal starts with numbers. Whether you want to lose 20 pounds, run a faster 5K or finally hit a 225-pound bench press, guessing gets you nowhere — measuring does. Our calculators use the same formulas used by dietitians, coaches and sports scientists: the Mifflin-St Jeor equation for calories, the U.S. Navy method for body fat, and Epley's equation for strength.
Each calculator explains the math in plain English, walks through a complete worked example, and answers the questions people ask most. Every result is instant, private and free — nothing you type ever leaves your browser.
How It Works
- Pick a calculator: Choose the number you want to know — BMI, body fat, daily calories, macros, training zones or anything else on this page.
- Enter a few details: Type in your height, weight, age and activity level. It takes under a minute and works in both metric and imperial units.
- Get your numbers: Each calculator returns your result instantly, explains what it means, and shows the healthy or recommended range to aim for.
Frequently Asked Questions
How accurate are these calculators?
They use the same formulas used by dietitians, coaches and sports scientists: the Mifflin-St Jeor equation for calories, the U.S. Navy method for body fat, and Epley's equation for strength. Results are reliable estimates — individual metabolism and body composition vary, so treat the numbers as a starting point rather than an exact measurement.
Is BMI or body fat percentage more important?
Body fat percentage is more meaningful for people who train, because BMI cannot tell muscle from fat — muscular people often score as overweight on BMI while carrying little body fat. For a quick general screen, BMI is fine. If you lift weights regularly, use the body fat calculator instead.
How many calories should I eat to lose weight?
A sustainable approach is to eat about 300–500 calories below your total daily energy expenditure (TDEE), which produces roughly 0.5 to 1 pound (0.2–0.5 kg) of loss per week. Avoid eating below your basal metabolic rate (BMR) for long periods. The TDEE and calorie calculators on this page do the math for you.
Are these calculators a substitute for medical advice?
No. They are educational tools for general information only. Results are estimates, not diagnoses or treatment plans. Talk to a qualified healthcare professional before starting a new diet, supplement or exercise program, especially if you have a medical condition.
Do I need to pay or create an account?
No. Every calculator is free, needs no sign-up, and works entirely in your browser. Nothing you enter is stored or sent to a server.
Can I use these calculators on my phone?
Yes — all calculators are mobile-friendly and take less than a minute to use, whether you are at the gym, at the grocery store or at home planning your week.