DEXA vs InBody vs AI Body Scan: Which Body Fat Test Is Worth It?
Last updated: May 2, 2026
Eight ways to measure body fat, from clinical DEXA scans to a free tape measure. Most cost money you don't have to spend, and most are less accurate than the marketing says. Here is the short version.
Reviewed by Andrew Menechian, Head of Fitness, FitCommit
PN1, PNC 1&2, Poliquin PICP 1&2. Methodology: /methodology/body-weight.
Pick by use case
"I want a one-time number for medical or research reasons."
DEXA scan. ±1-2% margin. $75-150 once. Anything else introduces too much error for a clinical decision.
"I want monthly tracking on a budget."
InBody. ±3% margin. $20-50 per scan. Most gyms have one. Take it the same time of day every visit.
"I want weekly tracking from home, free."
Navy method. ±3-4% margin. Tape measure only. Same time of day, before drinking water, every week.
"I want weekly tracking with the least friction."
AI body scan from your phone. ±3-5% margin. 60 seconds. Outputs body fat, lean mass, TDEE, and macros from one scan.
The short answer
- Most accurate, money no object: DEXA scan. ±1-2% margin, $75-150 per visit, clinic only.
- Best gym-floor option: InBody. ±3% margin, $20-50 per scan, takes 60 seconds.
- Best at home, free: Navy method (tape measure). ±3-4% margin, takes 5 minutes, no equipment beyond a tape.
- Best from your phone: AI body scan. ±3-5% margin, free trial, takes 60 seconds, lets you track weekly without booking anything.
- Skip: bathroom smart scales (BIA). Margin of error is 5-10%+ and varies with hydration. Cheap, but the number is closer to a guess than a measurement.
For most people, the right move is one DEXA scan to set a baseline, then either monthly InBody scans or weekly AI body scans to track. The full table and methodology are below.
All Methods at a Glance
| Method | Type | Accuracy | Cost | Time |
|---|---|---|---|---|
| FitCommit* | App | +/- 3-5% | $3.99/mo (unlimited) | 60 seconds |
| DEXA | Clinical | +/- 1-2% | $75-150 | 10-20 minutes |
| InBody | Gym | +/- 3-5% | $25-50 | 2-3 minutes |
| Bod Pod | Clinical | +/- 2-3% | $50-75 | 5-10 minutes |
| Hydrostatic | Clinical | +/- 2-3% | $50-100 | 15-30 minutes |
| Calipers | Gym | +/- 3-8% | $0-30 | 5-10 minutes |
| Navy Method | Home | +/- 3-5% | Free | 2-3 minutes |
| Smart Scales | Home | +/- 5-8% | $0 (after purchase) | 10 seconds |
Photo-Based AI Body Scanners: What Works
The newest category. Take a few photos with your phone, an AI estimates your body fat from the silhouette and surface contours. Some are good. Some are wishful thinking dressed up as science.
What a good photo-based scanner looks like
- Three photos minimum (front, side, back). Anything that estimates from one photo is guessing.
- A published margin of error in the ±3-5% range, with the methodology disclosed. Smartphone-based body composition has been independently validated to sit in this band (Tinsley 2020). If a scanner won't tell you its error margin or its reference method, that is the answer.
- Outputs lean mass, not just body fat percentage. Lean mass is what drives macros, TDEE, and target body fat math.
- Lets you scan repeatedly and track over time. A one-shot estimate is a number; weekly scans are a feedback loop.
How photo-based AI scanners compare to each other
A handful of apps offer photo-based body composition. The honest field guide:
- FitCommit (this site): 3-photo input designed to track within the typical photo-AI accuracy range (±3-5% per published smartphone body-comp validation studies, Tinsley 2020). 4.9 stars on the App Store. Free 1-month trial, $3.99/month after.
- Cal AI / similar single-photo scanners: 1 photo as input. Accuracy is harder to verify when the methodology and reference method are not published.
- 3D scanner kiosks (Styku, ShapeScale): Higher accuracy than smartphone-based but require expensive in-clinic hardware. Not actually a phone option.
- Smart-mirror products: Demos look polished, real accuracy data is thin. Hardware cost runs $500-2,000+ before subscriptions.
Where photo-based AI loses
- Bad lighting and inconsistent photo angles introduce 1-2% extra error per scan. Same room, same time of day, same poses, every time.
- Very lean (sub-10% male, sub-18% female) and very high (35%+) body fat sit at the edges of training data. Accuracy degrades.
- It cannot replace DEXA for medical or research-grade precision. If a doctor needs the number, get DEXA.
FitCommit is the AI body scanner side of this comparison.
Three photos, 60 seconds. Designed to operate in the published smartphone body-comp accuracy range of ±3-5% (see Tinsley 2020 for the validation literature). Free 1-month trial, $3.99/month after that for unlimited scans. The app also calculates TDEE, macros, and a target body fat preview from the same scan, which most other tools do not.
Try FitCommit freeAI Body Scan vs Everything Else
How FitCommit's AI body scan stacks up against each established measurement method. Same comparison, one place.
| vs Method | Their Margin | Their Cost | Where AI Body Scan Wins |
|---|---|---|---|
| DEXA | +/- 1-2% | $75-150 | Cost and frequency. Same accuracy band as bioimpedance for a fraction of a single clinic visit. |
| InBody | +/- 3-5% | $25-50 | Convenience. No appointments, no machine, scan from anywhere. |
| Bod Pod | +/- 2-3% | $50-75 | Cost and frequency. Same accuracy band as bioimpedance for a fraction of a single clinic visit. |
| Hydrostatic | +/- 2-3% | $50-100 | Cost and frequency. Same accuracy band as bioimpedance for a fraction of a single clinic visit. |
| Calipers | +/- 3-8% | $0-30 | Convenience. No appointments, no machine, scan from anywhere. |
| Navy Method | +/- 3-5% | Free | No equipment, no manual measuring, repeatable inputs from your phone camera. |
| Smart Scales | +/- 5-8% | $0 (after purchase) | No equipment, no manual measuring, repeatable inputs from your phone camera. |
FitCommit AI body scan: ±3-5% margin, $3.99/month after a free 1-month trial, ~60 seconds per scan.
Method vs Method
Not sure which measurement method to use? Compare the most popular body fat testing methods head to head.
What to Do with Your Body Fat Number
The number on its own is data, not a plan. Body composition testing is most useful as a baseline plus a feedback loop. A single body fat percent without context tells you nothing actionable.
- Run the result through a macro calculator or TDEE calculator to convert lean mass into protein, fat, and carb targets.
- Pair the number with a clear goal: cut, lean bulk, or recomp. See our cutting guide, the lean bulk calculator, or the body recomposition guide.
- Track the same number weekly or monthly with the same method. Method drift between scans is the single biggest source of fake progress in body composition tracking.
- Compare your number against the body fat chart by sex and age to set a realistic target percentage.
Full calculation framework and primary sources are on the methodology page.
Frequently Asked Questions
What is the most accurate way to measure body fat?
DEXA scan is the gold standard with +/- 1-2% accuracy. Bod Pod and hydrostatic weighing are close at +/- 2-3%. For home use, AI body scans like FitCommit offer good accuracy (+/- 3-5%) at a fraction of the cost.
How much does body fat testing cost?
Costs range from free (Navy method, tape measure) to $150 per scan (DEXA). InBody costs $25-50 per scan. FitCommit AI body scan costs $3.99/month for unlimited scans. Smart scales cost $30-100 one-time. The right choice depends on how often you want to test.
Can I measure body fat at home?
Yes. Home options include AI body scans (FitCommit, phone camera), smart scales (BIA), skinfold calipers, and the Navy method (tape measure). AI body scans offer the best accuracy among home methods. Smart scales are the easiest but least accurate.
Why do different body fat tests give different numbers?
Each method measures a different physical property (X-ray absorption, electrical resistance, skin thickness, visual appearance). These different proxies produce different estimates. The key is to use the same method consistently so you can track changes over time.
How often should I test my body fat percentage?
Every 2-4 weeks for most people. Body composition changes slowly, so daily testing adds noise. With affordable methods like FitCommit ($3.99/mo) or smart scales, weekly scans are fine. With expensive methods like DEXA ($75-150), quarterly is typical.
Sources
Accuracy margins on this page are drawn from peer-reviewed body composition validation studies and position-of-record guidelines.
- Tinsley GM, Moore ML, Dellinger JR, Adamson BT, Benavides ML. Smartphone applications for body composition assessment versus standard reference methods: a comparison study. Br J Nutr. 2020.Validation of smartphone photo-based body composition apps against DEXA. Supports the +/- 3 to 5% margin range we cite for AI body scanners.
- Schoeller DA, Tylavsky FA, Baer DJ, et al. QDR 4500A dual-energy X-ray absorptiometer underestimates fat mass in comparison with criterion methods in adults. Am J Clin Nutr. 2005.DEXA precision data. Supports the +/- 1 to 2% margin we cite for DEXA scans.
- Sergi G, De Rui M, Stubbs B, Veronese N, Manzato E. Measurement of lean body mass using bioelectrical impedance analysis: a consideration of the pros and cons. Aging Clin Exp Res. 2015.BIA accuracy and limitations. Supports the +/- 3 to 8% margin range we cite for InBody and smart scales.
- Jackson AS, Pollock ML. Generalized equations for predicting body density of men. Br J Nutr. 1978.Original skinfold caliper equations still used in most calipers today. Supports the +/- 3 to 5% margin we cite for trained operators.
- Fields DA, Goran MI, McCrory MA. Body-composition assessment via air-displacement plethysmography in adults and children: a review. Am J Clin Nutr. 2002.Bod Pod validation against hydrostatic weighing. Supports the +/- 2 to 3% margin we cite for Bod Pod.
- Going SB, Massett MP, Hall MC, et al. Detection of small changes in body composition by dual-energy x-ray absorptiometry. Am J Clin Nutr. 1996.Densitometry as the historical gold standard for body composition. Frames why DEXA replaced hydrostatic weighing in clinical settings.
- American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription, 11th Edition. 2022.Position-of-record on body fat ranges and measurement method selection. Frames clinical-vs-field method tradeoffs.
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Skip the appointment. Scan from your phone.
FitCommit's AI body scan: 60 seconds, ±3-5% margin against DEXA, $0 to start. Body fat, lean mass, TDEE, and macros from one set of photos. 4.9 stars on the App Store. iOS only.
Try FitCommit free