Free wellness calculators
Know your numbers before you plan around them.
Twenty clinically grounded calculators — body composition, metabolism and daily nutrition targets — with one shared profile so the first one asks and every one after is instant.
No sign-up required20 calculatorsBuilt on established clinical formulas
Try it now
BMI Calculator
Body mass index against the WHO reference ranges.
Fill in the fields to see your result.
How it works
Fill in your numbers once.
Answer age, sex, height and weight for your first calculator — every calculator after that opens pre-filled.
1st
Pick a calculator
Start anywhere — BMI and TDEE are common starting points.
2nd
Answer a few fields
Most take under 30 seconds. Your answers are saved on this device only.
3rd
Get a clear result
A number, a status, and what it means — plus what to check next.
FAQ
Common questions
Are these calculators medically accurate?
Each one uses an established, published formula (Mifflin-St Jeor, WHO BMI bands, the US Navy body-fat method, and similar) — but results are estimates for general wellness guidance, not a diagnosis. See each calculator’s "the science" section for its exact method.
Where is my data stored?
Your answers are saved only in your browser (localStorage) so calculators can autofill for you. Nothing is sent to EatFitt unless you choose to book a consult.
Why do I only have to enter my details once?
EatFitt remembers your age, sex, height, weight and activity level on this device, and every calculator that needs them opens pre-filled — you only fill in what’s specific to that calculator.
Can I use metric and imperial units?
Yes — every calculator has a metric/imperial toggle, and switching converts your existing values rather than resetting them.
Beyond the numbers
A calculator tells you where you are.
A dietitian-built plan tells you how to get where you’re going. Book a free 20-minute consult — no card, no obligation.
These calculators provide general wellness estimates based on established formulas and are not a substitute for professional medical advice, diagnosis or treatment. If you have a medical condition or are pregnant, consult a qualified healthcare provider before making changes based on these results.