Fitness & Health Calculators
Work out your BMI and body fat, your BMR and daily calorie needs, your macros and protein target, your ideal weight and one-rep max, your heart-rate zones and how much water to drink. Free, instant, and calculated entirely in your browser — your measurements never leave your device.
Body Composition
BMI Calculator
Body mass index from height and weight, with category and a healthy weight range for your height.
BMI Calculator (Metric)
BMI in centimetres and kilograms, with your category and healthy weight range.
BMI Calculator (Imperial)
BMI in feet, inches and pounds, with category and a healthy weight range in pounds.
BMI Calculator for Women
BMI for adult women, with the healthy range and the body-composition context that matters most.
BMI for Kids & Teens
Child and teen BMI with the caveat that children are assessed on age-and-sex percentile charts, not adult bands.
BMI Chart
Check the healthy weight range for your height and read the WHO BMI bands at a glance.
Body Fat Calculator
Estimate body fat percentage from tape measurements with the US Navy method, plus fat mass and lean mass.
Body Fat Percentage Calculator
Find your body fat percentage and where it sits against healthy ranges for your sex.
Army Body Fat Calculator
The US Army circumference method for body fat, using neck, waist and hip measurements.
Navy Body Fat Calculator
The US Navy circumference formula for body fat, with the exact measurement sites.
Lean Body Mass Calculator
Lean body mass and fat mass from your weight and body fat percentage.
Ideal Weight Calculator
Ideal body weight from the Devine, Robinson, Miller and Hamwi formulas, alongside the healthy BMI range.
Waist-to-Hip Ratio Calculator
Waist-to-hip ratio and the WHO risk thresholds for fat distribution.
Body Recomposition Calculator
Calorie and protein targets for losing fat while building or holding muscle.
Calories & Energy
Calorie Calculator
Daily calories to maintain, lose or gain weight, based on your BMR and activity level.
BMR Calculator
Basal metabolic rate — the calories your body burns at complete rest.
TDEE Calculator
Total daily energy expenditure — all the calories you burn in a day, rest and activity included.
Maintenance Calories Calculator
The calories that keep your weight stable, from your BMR and activity level.
Calorie Deficit Calculator
The daily calorie intake that produces your chosen rate of weight loss.
Calories Burned Calculator
Calories burned in an activity from its MET value, your weight and the duration.
Mifflin-St Jeor Calculator
BMR with the Mifflin-St Jeor equation, the most accurate general-purpose formula.
Harris-Benedict Calculator
BMR with the revised Harris-Benedict equation, the long-standing clinical standard.
Katch-McArdle Calculator
BMR from lean body mass, the best fit when you know your body fat percentage.
Macros & Nutrition
Macro Calculator
Protein, carbohydrate and fat targets in grams from a daily calorie target and a chosen split.
Macro Calculator for Weight Loss
Fat-loss macros with a high protein share to protect muscle while in a deficit.
Protein Calculator
Daily protein target in grams based on body weight and goal.
Carb Calculator
Daily carbohydrate target in grams from your calories and macro split.
Keto Macro Calculator
Keto macros: around 70% fat, 25% protein and under 5% carbohydrate.
Weight Management
Weight Loss Calculator
How long it will take to reach your goal weight at a chosen rate of loss.
Weight Loss Goal Date Calculator
Pick a goal date and see the daily deficit and weekly rate it requires.
Goal Weight Calculator
Find a healthy goal weight from your height, then see the timeline to reach it.
Weight Loss Percentage Calculator
How much of your starting weight you have lost, as a percentage.
Calories in a Pound of Fat
Why a pound of fat is treated as 3,500 kcal, and what a deficit really produces.
Intermittent Fasting Calculator
Eating window and fasting schedule for 16:8, 18:6, 20:4 and 14:10 plans.
Strength & Cardio
One Rep Max Calculator
Estimate your one-rep max from any set, with five formulas and a full percentage chart.
1RM Calculator
One-rep max from a working set, with the Epley, Brzycki and Mayhew estimates side by side.
Bench Press Calculator
Estimate your bench press 1RM from a working set, with a percentage chart for programming.
Squat Calculator
Estimate your squat 1RM from a set, with the percentage chart for programming.
VO2 Max Calculator
Estimate aerobic capacity from resting heart rate or a 12-minute run, with a fitness rating.
Heart Rate Zones Calculator
Five training zones from your age and resting heart rate, using the Karvonen method.
Max Heart Rate Calculator
Estimated maximum heart rate from age, using the Tanaka, Fox and Nes formulas.
Fat Burning Heart Rate Calculator
The heart-rate range where fat contributes the most to your energy use.
Hydration & Activity
Water Intake Calculator
How much water to drink a day, scaled to your body weight, exercise and climate.
Steps to Miles Calculator
Convert steps to miles or kilometres using your height and stride length.
Steps to Calories Calculator
Estimate calories burned from a step count, scaled to your body weight.
Calories Burned Walking Calculator
Calories burned walking from your weight, duration and pace.
Browse by Category
Body Composition Calculators
Body composition is a fuller picture than weight alone: it answers how much of you is fat, how much is lean tissue, and where the …
Calorie & Weight Calculators
Energy balance decides weight change, and these calculators make it concrete. Start with BMR and TDEE to find your maintenance cal…
Guides
What Is BMI?
What body mass index measures, where the categories come from, and what it cannot tell you.
BMR vs TDEE
The difference between resting metabolism and total daily energy expenditure, and how to use each.
How Many Calories to Lose Weight
How to set a calorie target for fat loss, and why the first number is only a starting point.
How to Calculate Macros
Turn a calorie target into protein, carbohydrate and fat grams — with a worked example.
What Is Body Fat Percentage?
How body fat percentage differs from BMI, how it is measured, and what healthy ranges look like.
How to Calculate Your TDEE
Three ways to find your total daily energy expenditure, and how to verify it with real data.
Calorie Deficit Explained
Why a deficit is the only thing that causes fat loss, how big it should be, and why progress stalls.
About these calculators
FitCalc provides free health and fitness calculators for general education. All results are estimates based on published formulas and are not medical advice or a diagnosis. Body composition, calorie needs and fitness vary between individuals — speak to a qualified healthcare professional before making decisions about your health, diet or training.