Health Calculators
Understanding your body starts with understanding your numbers. Our free health calculators estimate daily calorie needs, metabolic rate, body composition and more — using peer-reviewed formulas such as Mifflin-St Jeor, with sources cited on every page. Results appear instantly and every tool explains the science behind the math, including worked examples and honest limitations. These tools are for information and planning only; always consult a qualified professional for medical advice.
TDEE Calculator
Discover how many calories you burn per day — and what to eat to lose, maintain, or gain weight.
Body Fat Calculator
Find your estimated body fat percentage with just a tape measure — plus your fat mass, lean mass, and fitness category.
Protein Intake Calculator
How much protein do you really need? Get a research-backed daily target for your weight and goal — plus a simple per-meal breakdown.
BMR Calculator
Your body burns calories even doing nothing. Find your Basal Metabolic Rate — the foundation of every calorie plan.
Macro Calculator
Turn your calorie target into daily protein, carbs, and fat grams — pick a proven split or dial in your own.
Water Intake Calculator
Forget the "8 glasses" myth — get a hydration target matched to your weight, your activity, and your climate.
Ideal Weight Calculator
See the classic clinical weight formulas side by side — Devine, Robinson, Miller — plus your healthy BMI range.
Due Date Calculator
When will your baby arrive? Get an estimated due date from your last period or conception date — plus how far along you are today.
Heart Rate Zones Calculator
Stop guessing your effort — get your 5 heart rate training zones from your age, personalized with your resting heart rate.
Pace Calculator
Pace, time, distance — know any two, get the third instantly. Works in kilometers and miles.