AI body fat from a photo and a tape measure
One photo gives a guess. A photo plus a tape measure gives a range you can track.
Short answer
To get a body-fat estimate you can actually track, combine an AI read of your photos with a tape-measure estimate. ProgressLens does this in one tap: the AI reads your front, side and back photos, the US Navy formula uses your waist, neck and height, and your history smooths it, giving one range with a confidence level that stays consistent check-in to check-in.
Why one photo isn’t enough
Lighting from above, a pump, a slight twist or tight shorts can change how lean you look by several points. In our analysis of 10,218 Reddit posts, people quoting estimates from different AIs for the same photos saw gaps of 2 to 8 points.
Your progress reportWhere you are
16–18%
Estimated body fat · medium confidence
- From photos: 15–19%
- From tape measurements: 17.2%
What changed
Weight −3.1 lbWaist −0.8 in
- Waist: more defined
- Abs: more defined
- Shoulders: unchanged
Is it working
On track
Your waist is shrinking faster than your arms and shoulders: mostly fat loss.
What to do next
Cut
- Lose 0.7–1.1 lb a week
- About 12 weeks to around 12% body fat
- Next check-in in about two weeks, in the same place and light.
Estimates from your photos and measurements, not a medical assessment.
How the two sources are combined
| Source | Good at | Weak at |
|---|---|---|
| AI photo read | Seeing where fat sits and how defined you are | Light, pose, clothing |
| Tape measure (US Navy) | Repeatable, cheap, not fooled by light | Body shape quirks, measuring technique |
| Your history | Ignoring one-off bad photos | Needs a few check-ins |
ProgressLens shows each part (from photos, from tape) and the combined range, so you can see when they agree and when one is off.
Take measurements that the formula can use
- Waist: at the navel, relaxed, after breathing out.
- Neck: just below the larynx, tape sloping slightly down to the front.
- Hips (women): at the widest point of the buttocks.
- Same time of day, same tape, every time.
Read how to measure your waist or use the tape-measure calculator.
FAQ
Frequently asked questions
How accurate is the body-fat estimate?
It’s an estimate, shown as a range with a confidence level, not a lab test. ProgressLens combines what the AI sees in your photos with the US Navy tape-measure formula and your own history, so the number doesn’t jump around from one photo to the next. The same photos always give the same result. Use it to follow your trend.
Is the US Navy tape method accurate?
Against DEXA it is typically within about 3–4 points for most people, and it’s very repeatable if you measure the same way. That repeatability is why ProgressLens uses it as an anchor.
Can I get a body-fat estimate for free?
Yes: the body fat estimator gives a first range in your browser from how you look and your tape measurements. The AI read of your photos, tracked over time, is what the app adds.
Are my photos private?
Yes. They stay inside the app on your phone, not in your gallery or a cloud, and there’s no account. When you tap AI Analyze, only the photos you chose for that report are sent to the AI. They’re not stored and not used to train any AI.