FitCommit vs Hydrostatic Weighing: Which Is Better?

Last updated: February 13, 2026

The Verdict

Hydrostatic wins on accuracy. FitCommit wins on cost, convenience, and tracking frequency. For most people who want to track body fat regularly without spending $75-150 per visit, FitCommit is the practical choice. Use Hydrostatic for quarterly validation if you want clinical-grade precision.

Quick Overview

Our App

FitCommit AI Body Scan

Good accuracy

Accuracy+/- 3-5%

Cost$3.99/mo (unlimited)

Time60 seconds

WherePhone camera, anywhere

Hydrostatic Weighing

Very good accuracy

Accuracy+/- 2-3%

Cost$50-100

Time15-30 minutes

WhereUniversities and specialized labs

How Each Method Works

FitCommit AI Body Scan

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.

Hydrostatic Weighing

Also called underwater weighing. You sit on a scale submerged in a pool of water, exhale completely, and hold still while your underwater weight is recorded. The difference between your land weight and underwater weight determines body density, which calculates body fat percentage.

Head-to-Head Comparison

Category	FitCommit	Hydrostatic	Winner
Accuracy	Good (+/- 3-5%)	Very good (+/- 2-3%)	Hydrostatic
Cost	$3.99/mo (unlimited)	$50-100	FitCommit
Convenience	Phone camera, anywhere	Universities and specialized labs	FitCommit
Time Per Test	60 seconds	15-30 minutes	FitCommit
Tracking Frequency	Weekly or more	Quarterly	FitCommit

Pros and Cons

FitCommit

Pros

✓Scan anytime from your phone. No appointments, no equipment.
✓Unlimited scans for $3.99/month. Track progress weekly.
✓Also calculates TDEE, macros, and transformation timelines.
✓Results include lean mass, not just body fat percentage.
✓Free 7-day trial to test accuracy before committing.

Cons

×Less accurate than clinical methods like DEXA or Bod Pod.
×Requires good lighting and consistent photo angles for best results.
×AI estimation, not direct measurement of tissue density.

Hydrostatic

Pros

✓One of the oldest and most validated methods in body composition science.
✓Very accurate when performed correctly.
✓No radiation exposure.
✓Considered a reference method alongside DEXA.

Cons

×Extremely limited availability. Almost no commercial locations.
×Must be fully submerged in water and exhale completely.
×Uncomfortable for many people (holding breath underwater).
×Accuracy depends on complete lung exhalation, which varies per person.
×$50-100 per test with very few repeat testing opportunities.

Which Should You Choose?

Choose FitCommit if:

✓People who want to track body composition regularly without clinic visits.
✓Budget-conscious users who cannot afford $75-150 DEXA scans.
✓Anyone who wants body fat, TDEE, macros, and timelines in one app.

Choose Hydrostatic if:

✓Research settings with established underwater weighing protocols.
✓People curious about the original gold standard method.

Frequently Asked Questions

How accurate is FitCommit compared to a DEXA scan?

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.

Can an AI body scan replace clinical measurements?

For general fitness tracking, yes. FitCommit provides body fat percentage, lean mass, TDEE, and macros from your phone camera. For medical diagnostics or research, clinical methods like DEXA remain the standard.

How often should I measure body fat?

Every 2-4 weeks is ideal. More frequent than weekly adds noise without useful signal. With FitCommit, you can scan as often as you like since it costs $3.99/month for unlimited scans. Clinical methods are typically quarterly due to cost.

Does hydration affect AI body scan accuracy?

Hydration has minimal effect on AI visual analysis compared to BIA methods (InBody, smart scales) where it can shift results by 2-3%. For best results with FitCommit, scan at the same time of day in consistent lighting.

Related Guides

Cutting Guide

6 deficit levels with timelines and calorie targets for fat loss phases

Bulking Guide

3 surplus levels with timelines and calorie targets for muscle gain phases

Weight Loss Timeline

Exact timelines for losing 5, 10, 20, 50, or 100 pounds at different deficit levels

Calorie Guide

Understand deficit and surplus percentages with TDEE calculations

Get Your Body Fat Percentage in 60 Seconds

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

FitCommit vs Hydrostatic Weighing: Which Is Better?

Last updated: February 13, 2026

The Verdict

Quick Overview

Our App

FitCommit AI Body Scan

Good accuracy

Accuracy+/- 3-5%

Cost$3.99/mo (unlimited)

Time60 seconds

WherePhone camera, anywhere

Hydrostatic Weighing

Very good accuracy

Accuracy+/- 2-3%

Cost$50-100

Time15-30 minutes

WhereUniversities and specialized labs

How Each Method Works

FitCommit AI Body Scan

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.

Hydrostatic Weighing

Head-to-Head Comparison

Category	FitCommit	Hydrostatic	Winner
Accuracy	Good (+/- 3-5%)	Very good (+/- 2-3%)	Hydrostatic
Cost	$3.99/mo (unlimited)	$50-100	FitCommit
Convenience	Phone camera, anywhere	Universities and specialized labs	FitCommit
Time Per Test	60 seconds	15-30 minutes	FitCommit
Tracking Frequency	Weekly or more	Quarterly	FitCommit

Pros and Cons

FitCommit

Pros

✓Scan anytime from your phone. No appointments, no equipment.
✓Unlimited scans for $3.99/month. Track progress weekly.
✓Also calculates TDEE, macros, and transformation timelines.
✓Results include lean mass, not just body fat percentage.
✓Free 7-day trial to test accuracy before committing.

Cons

×Less accurate than clinical methods like DEXA or Bod Pod.
×Requires good lighting and consistent photo angles for best results.
×AI estimation, not direct measurement of tissue density.

Hydrostatic

Pros

✓One of the oldest and most validated methods in body composition science.
✓Very accurate when performed correctly.
✓No radiation exposure.
✓Considered a reference method alongside DEXA.

Cons

×Extremely limited availability. Almost no commercial locations.
×Must be fully submerged in water and exhale completely.
×Uncomfortable for many people (holding breath underwater).
×Accuracy depends on complete lung exhalation, which varies per person.
×$50-100 per test with very few repeat testing opportunities.

Which Should You Choose?

Choose FitCommit if:

✓People who want to track body composition regularly without clinic visits.
✓Budget-conscious users who cannot afford $75-150 DEXA scans.
✓Anyone who wants body fat, TDEE, macros, and timelines in one app.

Choose Hydrostatic if:

✓Research settings with established underwater weighing protocols.
✓People curious about the original gold standard method.

Frequently Asked Questions

How accurate is FitCommit compared to a DEXA scan?

Can an AI body scan replace clinical measurements?

How often should I measure body fat?

Does hydration affect AI body scan accuracy?

Related Guides

Cutting Guide

6 deficit levels with timelines and calorie targets for fat loss phases

Bulking Guide

3 surplus levels with timelines and calorie targets for muscle gain phases

Weight Loss Timeline

Exact timelines for losing 5, 10, 20, 50, or 100 pounds at different deficit levels

Calorie Guide

Understand deficit and surplus percentages with TDEE calculations

Get Your Body Fat Percentage in 60 Seconds

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