# Before/After Flexibility Meter | Free Tool | 321 STRONG

> Measure hamstring, hip, ankle or shoulder range with your phone

**URL:** https://321strong.com/tools/flexibility-meter

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Progress Tracking Free  
# Before/After Flexibility Meter
 Measure a joint angle with your phone's motion sensor, do a short guided session, then measure again and see the change in degrees.

               
Free tools from the team behind 321 STRONG foam rollers.

 [Shop 321 STRONG on Amazon →](https://www.amazon.com/stores/321STRONG/page/032D49F7-CEC1-4EDB-B1E4-684E7AB0001C?maas=maas_adg_F4D5512AD692C30138B6764655B5DC4E_afap_abs&ref_=aa_maas&tag=maas&321src=tool-detail-cta)       The Before/After Flexibility Meter turns your phone into an angle gauge. Hold or strap the phone against your shin or forearm, move to the end of your range and hold still: the motion sensor reads how far that part of the body turned from the start position, in degrees. Each side is measured three times and the best reading counts. A short guided session for that area follows, using the same rolling and stretching videos as our video library, and then you measure again to see the change. Readings are estimates, usually within a few degrees, so compare yourself with yourself rather than with a chart. Results stay in your browser and nothing is uploaded.

     
## How This Tool Works
 
321 STRONG has sold over 2 million foam rollers and spent 10+ years studying how people actually recover from training. The tools we build draw on that experience — combined with peer-reviewed research on myofascial release, recovery timing, and muscle physiology — to give you recommendations that are grounded in real evidence.

   🔬  Research-backed

 Inputs and outputs grounded in published sports science and recovery research.

    🎯  Personalized output

 No generic advice. Results adjust to your body, goals, and training history.

    ✅  Free, no signup

 All 321 STRONG tools are free to use. No account required, no email needed.

      
## Related Guides
[Acute Effects of Different Foam Rolling Volumes on Flexibility and PerformanceHow much rolling changes range.](/blog/acute-effects-of-different-foam-rolling-volumes-on-flexibility-and-performance)[Foam Rolling Hip Flexors: Release Tightness and Improve MobilityHip range before a hip test.](/blog/foam-rolling-hip-flexors-release-tightness-and-improve-mobility)[Foam Rolling Lats: Open Up Your Back and Improve PostureThe muscle behind overhead reach.](/blog/foam-rolling-lats-open-up-your-back-and-improve-posture)[Foam Rolling IT Band: Release Tightness Without PainWorking a stubborn area safely.](/blog/foam-rolling-it-band-release-tightness-without-pain)   
## Frequently Asked Questions
   
### How accurate is a phone at measuring flexibility?
 The motion sensor reads the phone's own tilt to within about a degree, but the measurement around it adds more: a strap can slip, soft tissue shifts under the phone, and the start position is never exactly the same twice. Expect readings to vary by a few degrees between tries. That is why the meter takes three tries per side and keeps the best, and why it is most useful for comparing you with yourself on the same day.

  
### Which flexibility tests can a phone measure?
 Movements where the limb turns about a horizontal axis: a straight-leg raise for the hamstrings, knee-to-wall for the ankle, seated hip rotation in both directions, and raising the arm overhead for the shoulder. Twisting movements such as thoracic rotation turn about a vertical axis, which the gravity sensor cannot see, so they are left out rather than guessed.

  
### Why can my range change after one short session?
 Trials on foam rolling and stretching have found short-term gains in range of motion after a single session, and this tool lets you see that on your own body. How much of the change is still there the next day is less certain, so measure again on another day before reading much into one result.

  
### Do I need to install an app?
 No. It runs in your phone's web browser. On an iPhone, Safari asks once for permission to use motion and orientation, so tap Allow. On a computer without a motion sensor you can enter degrees by hand, or scan the QR code to open the page on your phone.

  
### Where are my results stored?
 In your own browser, on the device you used. Nothing is sent to a server and no account is needed. The share button builds a link that carries only the test name and the four numbers, so you can send a result to someone without creating anything online.

       
## More Free Tools
  [📏 ### Flexibility Progress Tracker Track flexibility progress Try It Free →](/tools/flexibility-tracker)   [View All Tools →](/tools)