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GPS recorded distance seems too short or too long — how to fix it

Pacer Support
  • Updated

Outdoor GPS tracking relies on your device’s location chip and the strength of the satellite signals.  If distance looks way off — either much too long or far too short — the phone is likely struggling to get a clean GPS signal or is being limited by its settings.  Use the steps below to troubleshoot and improve GPS distance accuracy.

 

📌 Understand why GPS distance can be wrong

  • Not 100 % accurate: Running‑tracking apps use your phone’s GPS hardware.  Even with perfect conditions, most smartphone GPS chips have a small error margin.  Tall buildings, dense trees or carrying the phone in a pocket can cause the phone to miss part of your route or record outliers. 
  • Signal interference & satellite reception: GPS signals can be weakened by skyscrapers, heavy foliage, tunnels, valleys or even weather.  When the phone sees fewer satellites, the app may draw straight lines between points or “drift,” leading to distance errors.  Inaccurate GPS locations may either reduce or increase the recorded distance. 
  • Software & settings: Out‑of‑date apps or operating systems, battery saving modes and restrictive location permissions can interfere with GPS recording.  Hardware damage to the phone’s GPS antenna can also affect accuracy.

 

Knowing these factors will help you focus on the most likely causes.

 

✅ Quick checks before an activity

  1. Get a strong GPS lock – Start the app outside with a clear view of the sky and wait for it to lock onto satellites.  The GPS chip needs time to tune in; standing still for a few minutes helps improve accuracy.  Avoid starting the activity inside your house or under trees. 
  2. Check battery and temperature – Ensure your phone battery is above ~20 % and the phone isn’t overheating.  Heat or low battery can cause the phone to throttle GPS. 
  3. Switch off Wi‑Fi before starting – On some devices, Wi‑Fi signals can introduce location errors; turning it off helps the GPS chip get a more precise fix.

 

📱 iPhone: improve GPS distance accuracy

Follow these steps if you record GPS activities on an iPhone:

  1. Enable full Location Services and Precise Location 
    • Open Settings → Privacy & Security → Location Services. 
    • Make sure Location Services is ON and scroll down to your fitness app (e.g., Pacer).  Set it to “While Using the App” and toggle Precise Location ON. 
  2. Allow Background App Refresh 
    • Go to Settings → General → Background App Refresh. 
    • Find the app and turn Background App Refresh on.  GPS recording will pause if background refresh is disabled or if your phone is in Low Power Mode. 
  3. Avoid Low Power Mode during workouts 
    • Low Power Mode automatically disables background refresh and may limit GPS polling frequency.  Turn it off before starting a run or walk. 
  4. Reboot, reinstall or update when needed 
    • Force‑quit the app and other heavy applications.  Restart the phone to free up memory. 
    • If problems persist, delete and reinstall the app, then check that both the app and iOS are updated to the latest versions. 
  5. Toggle Airplane Mode & Auto‑pause settings (optional) 
    • Switching Airplane Mode on and off can help reset your connection. 
    • Disable auto‑pause if you rarely stop; it can misjudge when you’re moving slowly and can distort distance. 

 

🤖 Android: improve GPS distance accuracy

On Android phones, large distance errors usually stem from battery optimization or location settings.  To fix this:

  1. Use high‑accuracy location mode 
    • Open Settings → Location → Location Services → Location Accuracy and enable High Accuracy.  This uses GPS, Wi‑Fi and mobile networks for best precision. 
    • In some brands’ settings (Samsung, Xiaomi, etc.), choose High Accuracy or Phone Only; experiment to see which yields better results. 
  2. Grant location permission and precise location 
    • Go to Settings → Apps → Pacer → Permissions and ensure Location is allowed. 
    • Enable Use Precise Location so the app doesn’t only use approximate location. 
  3. Turn off battery savers and app sleeping 
    • Disable Battery Saver and other power‑saving modes (e.g., Adaptive Battery, Optimize Battery Usage, Put Apps to Sleep).  Phones often pause GPS to save power. 
    • Exempt your fitness app from battery optimization.  On Samsung devices, remove the app from “Sleeping Apps” and “Always Sleeping Apps” lists ; on MIUI or Huawei, allow the app to run in the background and disable optimization. 
  4. Wait for a good signal outdoors 
    • Before starting your activity, wait for the GPS indicator in the app to show strong signal.  Keep the phone outside of pockets and point it toward the sky.  Tall buildings, trees or running around small circles can worsen accuracy. 
    • Move away from Wi‑Fi routers when locking onto satellites. 
  5. Internet connection and A‑GPS data 
    • A brief internet connection helps the phone download A‑GPS data and find satellites faster.  If you start just outside your house, wait until the phone switches from Wi‑Fi to cellular to avoid mixed signals. 
  6. Restart or reset GPS 
    • Restart your phone to clear system caches. 
    • If problems continue, some apps (e.g., GPS Status & Toolbox) can reset the assisted‑GPS data, which may help reacquire satellites. 

 

🌍 Environment and carry tips

  • Open skies are best: GPS accuracy is highest when the phone has an unobstructed view of a wide section of the sky.  Pockets, armbands or backpacks can block signals.  Try holding the phone in your hand or using a slim belt. 
  • Avoid tall buildings and dense trees: Urban canyons and forests scatter satellite signals, causing “GPS drift” and inaccurate distance.  Change your route to more open areas when possible. 
  • Keep the phone stable: Rapid turns or bouncing can create extra zig‑zag points and overestimate distance.  For track runs or short loops, consider using a watch or record the distance manually.

 

🧭 Final checklist

  1. Start outdoors with a good satellite lock. 
  2. Enable precise location and allow the app to access location at all times. 
  3. Disable battery savers and allow the app to run in the background. 
  4. Keep the phone in a position with clear sky visibility. 
  5. Update both the app and your phone’s operating system regularly.

 

If you have followed these steps and still see large discrepancies, try recording a short run with another fitness app.  If all apps show large errors, your device’s GPS hardware may need service.