Fitness & Health Calculators

What These Calculators Do

Each tool gives an estimate based on the numbers you enter. Use the body-composition tools to check where you stand, the calorie and macro tools to plan food intake, and the hydration, training and recovery tools to plan workouts. All 12 tools are free and need no sign-up. Results are estimates for information only, not medical advice.

All 12 Calculators at a Glance

• BMI Calculator — Checks whether your weight falls within a healthy range for your height.
• BMR & TDEE Calculator — Estimates calories burned at rest (Mifflin-St Jeor) and total daily energy expenditure by activity level.
• Calorie Calculator — Estimates daily calories for losing weight, maintaining weight or building muscle.
• Macro Calculator — Gives a daily protein, carbohydrate and fat breakdown from your calorie target and goal.
• Body Fat Calculator — Estimates body fat percentage using the U.S. Navy circumference method.
• Ideal Weight Calculator — Shows an ideal body weight range using four well-known medical formulas (Devine, Robinson, Miller and Hamwi).
• Water Intake Calculator — Estimates daily water needs from body weight and activity level.
• Heart Rate Zone Calculator — Calculates 5 heart rate training zones using the Karvonen formula.
• Waist-to-Hip Ratio Calculator — Assesses abdominal obesity and related health risks from waist and hip measurements.
• One Rep Max Calculator — Estimates your one-rep max (1RM) from the weight lifted and reps performed.
• Pace Calculator — Finds pace, time or distance when you enter any two of the three values.
• Protein Calculator — Estimates recommended daily protein intake from body weight and activity goals.

Try the Calculators

Open the 12 free fitness and health calculators — BMI, BMR & TDEE, calories, macros, body fat, ideal weight, water intake, heart rate zones, waist-to-hip ratio, one rep max, pace, and protein.

How to Use These Calculators

Start with the tool that matches your goal, enter your measurements as asked, and read the result with the note on the tool. If you are planning food intake, use the BMR & TDEE result first, then the Calorie and Macro calculators. If a result surprises you, re-check the numbers you entered before acting on it.

Keep Reading

• Understanding Macros: A Simple Guide to Protein, Carbs, and Fats — How protein, carbs and fats fit into a daily plan.
• 10 High-Protein Breakfast Ideas for Busy Mornings — Easy ways to put a protein target into practice.
• Plant Based Protein – Sources, Benefits, and Meal Ideas — Plant-based options for meeting a protein target.

Frequently Asked Questions

Are these fitness calculators accurate?

They use established formulas such as the Mifflin-St Jeor equation for BMR, the U.S. Navy method for body fat estimation and standard WHO BMI ranges. Results are estimates and do not replace professional medical advice. Individual results may vary based on factors such as muscle mass, bone density and overall health.

What formula does the BMI calculator use?

BMI = weight (kg) ÷ height (m)². It follows the World Health Organization (WHO) classification: Underweight (below 18.5), Normal weight (18.5–24.9), Overweight (25–29.9) and Obese (30+). BMI is a screening tool; it does not directly measure body fat percentage and has limitations for athletes and muscular individuals.

How do I calculate my daily calorie needs?

First use the BMR & TDEE Calculator to find your Total Daily Energy Expenditure, using the Mifflin-St Jeor equation adjusted for activity level. Then use the Calorie Calculator to fine-tune for your goal: subtract about 500 calories per day for weight loss of about 0.5 kg per week, keep the same number for maintenance, or add 300–500 calories for lean muscle gain. For a personalized plan, consult a dietitian.

How much protein should I eat per day?

It depends on activity level and goals. The general Recommended Dietary Allowance (RDA) is 0.8 g per kilogram of body weight per day for sedentary adults. Active individuals commonly aim for 1.2–1.6 g per kilogram, and athletes building muscle often use 1.6–2.2 g per kilogram. The Protein Calculator gives a personalized target based on your weight and goal; spread your intake across meals.