BMI, body fat and more, all in one kit.
Free, easy health calculators that go beyond BMI, so you understand what your numbers really mean.
All calculators
Built for every body and every goal
Whatever you are working toward, BMI Kit pairs your BMI with body fat, waist and muscle for the fuller picture.
No sign-up. Instant results.
What BMI alone misses
BMI sees only your weight and height. We pair it with the metrics that actually describe your body.
- One weight-to-height number
- Cannot tell muscle from fat
- Misses where you carry fat
- Body fat percentage and FFMI
- Waist-to-height for hidden risk
- Tracks how your body changes
More than just BMI
BMI is only a starting point. We pair it with body fat, waist size and muscle, so you see the whole story instead of half of it.
Everything in one place
BMI, body fat, calories, ideal weight and more. Eight simple calculators, all free, all in one spot.
Clear and trustworthy
Built on the same formulas doctors use, drawn from peer-reviewed research and explained in plain English.
Watch your body composition, not just the scale
Save any result and see your weight, body fat and muscle trend over the weeks. The muscle view flags lean-mass loss early, which matters most during weight loss and on GLP-1 medication.
- Trends for weight, body fat and FFMI
- A muscle-at-risk alert when lean mass drops
- Private by default, no account needed
Learn the why behind the numbers
Plain-English guides on body composition, BMI and GLP-1 weight loss.
AI nutritionist: what ChatGPT gets right and wrong about your diet
AI nutritionist tools and ChatGPT promise personal diet advice. What they are genuinely good at, where they fall short, and how to get more out of them.
Can ChatGPT calculate your BMI and body fat?
ChatGPT can usually work out BMI, but body fat is where it guesses. Here is what it gets right, where it goes wrong, and how to get numbers you can trust.
ChatGPT for health: what it is good at, and where it is risky
Hundreds of millions of people ask ChatGPT health questions every week. A clear-eyed guide to where it genuinely helps, where it is risky, and how to use it safely.
Built on the same formulas clinicians use, drawn from peer-reviewed research.
Ready for a clearer picture?
It is free, instant and private. Add your details and see what your numbers really mean for you.
Calculate your BMI