Know your numbers.
Own your health.
A complete suite of accurate health and fitness calculators — BMI, metabolism, calories, body fat and more — each paired with a plain-English guide on what your results actually mean.
Every calculator you need, in one place
28 free tools across six categories. Pick one for an instant result, then read the guide below it to understand and act on your numbers.
Body composition 9
BMI Calculator
Body Mass Index from height and weight, with your healthy range.
Calculate BMI →Body Fat Calculator
Body fat % via the U.S. Navy method, plus fat and lean mass.
Estimate body fat →Body Water
Total body water and your body-water percentage (Watson).
Estimate body water →Lean Body Mass
Your fat-free mass from height, weight and sex.
Calculate LBM →Body Recomposition
Goal weight and fat to lose while keeping muscle.
Plan recomp →Ideal Weight
Target weight from four trusted clinical formulas.
Find ideal weight →Body Surface Area
Your BSA in m² (Mosteller, Du Bois, Haycock).
Calculate BSA →Waist-to-Hip Ratio
Your WHR and health-risk category.
Check your WHR →Waist-to-Height Ratio
Keep your waist under half your height.
Check your WHtR →Calories & metabolism 6
BMR Calculator
The calories your body burns at complete rest.
Find your BMR →TDEE Calculator
Total daily calories across every activity level.
Find your TDEE →Calorie Calculator
Maintenance calories plus loss and gain targets.
Get calorie targets →Calories to Lose Weight
Daily calories to reach a goal weight by a date.
Get your target →Calories Burned
Calories burned for any activity and duration.
Calculate burn →Steps to Calories
Calories burned and distance from your step count.
Convert steps →Nutrition 3
Macro Calculator
Turn a calorie target into protein, carbs and fat.
Split your macros →Protein Intake
Your daily protein target in grams.
Find your protein →Water Intake
How much water to drink each day.
Find your target →Fitness & performance 5
Pace Calculator
Running pace per km and mile, plus speed.
Calculate pace →One-Rep Max
Estimate your 1RM with a full percentage table.
Estimate 1RM →VO₂ Max
Estimate aerobic fitness from your resting heart rate.
Estimate VO₂ max →Target Heart Rate
Training zones for fat burning, cardio and peak effort.
Find your zones →Heart-Rate Recovery
Gauge fitness from how fast your pulse drops.
Check recovery →Women's health & pregnancy 3
Ovulation Calculator
Your fertile window and estimated ovulation day.
Find fertile days →Due Date Calculator
Pregnancy due date and gestational age.
Find your due date →Pregnancy Weight Gain
Recommended weight gain by BMI and week.
See your range →Health markers 2
Numbers are easy. Knowing what to do with them is the hard part.
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Trusted formulas
Every tool uses the same peer-reviewed equations clinicians and dietitians rely on — Mifflin-St Jeor, the U.S. Navy method, Devine and more.
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Context, not just a number
Each result comes with a long-form guide: what the figure means, how it's calculated, its limits, and the concrete next step.
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Fast & private
Results compute instantly in your browser. No accounts, no waiting, and your measurements never leave your device.
Guides to go with the numbers
Plain-English explainers that show you how to actually use what the calculators tell you.
Begin with the one number most people check first
Your BMI takes ten seconds and is the gateway to the rest of the toolkit.
Calculate my BMI