Fitness Calculators

Free, accurate calculators for BMI, calories, macros and more — every calculator includes the formula, a worked example and answers to common questions.

Body Calculators

BMI Calculator

Body Mass Index (BMI) is a quick screening measure that uses your height and weight to estimate whether your weight falls in a healthy range. It takes seconds to calculate and is widely used by doctors and fitness professionals as a starting point for a fuller health assessment.

Body Fat Calculator

Body fat percentage is a more direct measure of body composition than BMI, since it separates fat mass from lean mass. This calculator uses the US Navy circumference method, which requires only a measuring tape.

Ideal Weight Calculator

This calculator estimates an ideal body weight range using your height and gender, based on the Devine formula — one of the most widely referenced ideal-weight equations in clinical and fitness settings.

Lean Body Mass Calculator

Lean Body Mass (LBM) is your total body weight minus fat mass — everything else, including muscle, bone, organs and water. This calculator estimates it using the Boer formula, one of the more accurate equations available from simple height and weight inputs.

Calorie Calculators

BMR Calculator

Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic life-sustaining functions — breathing, circulation, cell production — while completely at rest. It is the foundation for figuring out your total daily calorie needs.

TDEE Calculator

Total Daily Energy Expenditure (TDEE) is the total number of calories you burn in a day, combining your Basal Metabolic Rate with the calories burned through daily activity and exercise. It is the number most people actually need to plan their nutrition around.

Calorie Calculator

This calculator estimates the number of calories you should eat each day to reach a specific goal — losing weight, maintaining your current weight, or gaining weight — based on your body stats and activity level.

Calorie Deficit Calculator

A calorie deficit means eating fewer calories than you burn, forcing your body to draw on stored energy (fat). This calculator turns a weekly weight-loss goal into a concrete daily calorie target.

Calorie Surplus Calculator

A calorie surplus means eating more calories than you burn, giving your body the extra energy it needs to build muscle and gain weight. This calculator turns a weekly weight-gain goal into a concrete daily calorie target.

Nutrition Calculators

Protein Calculator

Protein is essential for muscle repair, growth and overall health. This calculator estimates your daily protein target based on your body weight and how active you are, or whether your goal is muscle building.

Macro Calculator

Macronutrients (protein, carbohydrates and fat) each supply calories differently and serve different roles in the body. This calculator splits your daily calorie target into gram-based macro targets using a preset appropriate to your goal.

Water Intake Calculator

Staying adequately hydrated supports performance, recovery, digestion and general health. This calculator gives a starting-point daily water target based on your body weight, with an add-on for exercise.

Workout Calculators

One-Rep Max Calculator

Your one-rep max (1RM) is the most weight you could lift for a single repetition with good form. This calculator estimates it from a lighter set you have already performed, so you do not need to test a true max lift to program your training.

Pace Calculator

Pace is one of the most useful numbers for a runner — it turns a distance and time into a per-kilometre or per-mile rate you can use to plan training runs or predict race splits.

Running Calories Calculator

Running is one of the most calorie-efficient cardio exercises per minute. This calculator estimates calories burned from your body weight and the distance you ran.

Steps to Calories Calculator

Turning a daily step count into an estimated calorie burn requires converting steps to distance first, using your stride length, then applying a walking energy-expenditure estimate.

Heart Rate Zone Calculator

Training in different heart rate zones targets different fitness adaptations, from easy recovery to maximal effort. This calculator uses your age and resting heart rate to estimate five personalized training zones.