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Last updated: February 13, 2026
The Navy method is free but very rough, especially for muscular individuals. FitCommit provides a significantly more accurate estimate with additional data (lean mass, TDEE, macros) for $3.99/month. If you want more than a ballpark number, FitCommit is worth the small cost.
Good accuracy
Rough accuracy
Uses computer vision AI to analyze three photos (front, side, back) and estimate body fat percentage, lean mass, and body composition. Results in under 60 seconds.
Uses circumference measurements of your neck, waist, and hips (women only) along with your height. These measurements are plugged into a formula developed by the U.S. Navy to estimate body fat percentage. Originally created for military fitness assessments.
| Category | FitCommit | Navy Method | Winner |
|---|---|---|---|
| Accuracy | Good (+/- 3-5%) | Rough (+/- 3-5%) | FitCommit |
| Cost | $3.99/mo (unlimited) | Free | FitCommit |
| Convenience | Phone camera, anywhere | Home (tape measure only) | FitCommit |
| Time Per Test | 60 seconds | 2-3 minutes | FitCommit |
| Tracking Frequency | Weekly or more | Weekly or more | FitCommit |
FitCommit works well for tracking direction and rate of change during a prep. For stage-day precision (sub-1% accuracy), a DEXA scan closer to competition is recommended. Many competitors use FitCommit weekly and DEXA quarterly.
Most apps estimate TDEE from height, weight, age, and a generic activity multiplier. FitCommit measures your lean mass via body scan and uses the Katch-McArdle formula (BMR = 370 + 21.6 x lean mass in kg), which is more accurate because muscle tissue burns more calories than fat.
A smartphone camera, decent lighting, and form-fitting clothing (or minimal clothing). Take three photos: front, side, and back. The AI processes results in under 60 seconds. No special equipment or appointments needed.
FitCommit AI body scan has an error margin of +/- 3-5%, compared to DEXA at +/- 1-2%. For tracking trends over time, FitCommit is more practical because you can scan weekly for $3.99/month vs $75-150 per DEXA visit.
6 deficit levels with timelines and calorie targets for fat loss phases
3 surplus levels with timelines and calorie targets for muscle gain phases
Exact timelines for losing 5, 10, 20, 50, or 100 pounds at different deficit levels
Understand deficit and surplus percentages with TDEE calculations
AI body scan from your phone camera. Body fat percentage, lean mass, TDEE, and macros. No equipment. No gym. Free 7-day trial.
Try FitCommit Free