Body Composition Analysis
Free AI body fat calculator. Upload a photo, get your body fat percentage as a range, your waist, neck and hip measurements, and your calorie and macro targets. Your photos are never stored.
Frequently asked questions
How does HeavyAF measure body fat from a photo?
A pose detection model locates 33 body landmarks in your photo and a segmentation mask outlines your silhouette. From those, three circumferences are measured: neck, waist and hip. Together with your sex, age, height and weight they feed a regression model trained on 435 subjects whose body fat was measured by underwater weighing.
Is HeavyAF free?
Yes. Every feature is free: body composition analysis, measurement history, BMR and TDEE calculation, macro targets and the workout tracker. There is no paid tier, no trial and no credit card. Development is funded by optional donations.
Are my photos stored anywhere?
No. Photos exist only in memory for the few seconds the analysis takes, then they are discarded. Nothing is written to disk or to a storage bucket. Only the numeric results — measurements, body fat percentage and category — are saved to your account.
How accurate is a photo-based body fat estimate?
Expect roughly a 3-5% margin versus DEXA. It is a statistical estimate from a regression model, not a direct measurement, so treat it as a trend-tracking tool. Consistency matters more than the absolute number: same lighting, same pose, same time of day.
What is a healthy body fat percentage?
For men: under 6% is essential fat, 6-14% athletic, 14-18% fitness, 18-25% average, above 25% is elevated. For women: under 14% essential, 14-21% athletic, 21-25% fitness, 25-32% average, above 32% elevated. HeavyAF labels your result automatically.
How should I take the photo?
Stand 2-3 metres from the camera against a plain background, in fitted clothing or swimwear, arms slightly away from your torso and your whole body in frame. Even, front-facing light. For better accuracy use multi-view mode and add a side and back photo.
Do I need an account?
You need a free account to run an analysis and to keep your history. Sign-in is a magic link sent to your email — no password to choose or remember. You can delete your account and all associated data at any time from Settings.
Does HeavyAF calculate calories and macros too?
Yes. From your body fat result it derives lean body mass, then BMR via both Mifflin-St Jeor and Katch-McArdle, your TDEE from your activity level, and protein, fat and carb targets for cutting, maintaining or bulking.