Calibrating a Polar stride sensor with Grit X/Pacer/Vantage

The calibration process is sport profile-specific. When running on different surfaces (e.g. road, trail), use a different sport profile for each of them to achieve the best calibration for each surface.

Manual stride sensor calibration

Manual calibration can be done in two ways. You can run a distance you know and set the correct lap distance. You can also set the calibration factor manually if you know the factor which gives you accurate distance.

Calibrate the stride sensor manually by running a known distance:

  1. Browse to the running sport profile you want to use.
  2. Press LIGHT to enter the Quick menu and choose Calibrate stride sensor > Calibrate by running.
  3. Start the training session and run a distance you know. The distance has to be more than 400 meters.
  4. When you have ran the distance, press OK to take a lap.
  5. Set the actual distance you have ran and press OK. The calibration factor is updated.

Manual calibration can also be started during a session, when the stride sensor is in use. Pause the training session by pressing BACK and the choose Calibrate stride sensor from the Quick menu.

Please note that interval timer cannot used during the calibration. If you have set the interval timer on, the watch will ask you to turn it off to enable manual stride sensor calibration. You can turn the timer on from the pause mode quick menu after calibration.

Calibrate the stride sensor by setting the calibration factor:

  1. Browse to the running sport profile you want to use.
  2. Press LIGHT to enter the Quick menu and choose Calibrate stride sensor > Calibration factor.
  3. Set the calibration factor and press OK. Calibrated. Calibration factor: X.XXX is shown.

Automatic stride sensor calibration

Automatic stride sensor calibration is based on GPS data and it happens in the background. Pace, stride length and cumulative distance are updated and shown correctly after the automatic calibration. Note that your watch will not notify you about the calibration.

The automatic calibration is performed twice, and the average of the two calibration factors is used. In your next training session, the average of your previous calibration factor and the factor obtained during your current session is used.

The automatic calibration starts after 100 meters. The following criteria has to be met during the 500 meter calibration distance.

  • At least 6 satellites have to be available.
  • Speed has to be at least 7 km/h or 8.56 min/km (no stopping or walking allowed).
  • Ascent and descent are less than 30 meters.
  • If one of the above conditions is not met, the calibration process stops. The calibration process starts from the beginning as soon as all conditions are met.

Calibrating the stride sensor for indoor running

GPS is off by default in the Treadmill running sport profile, so in order to calibrate your stride sensor for indoor running you must turn GPS on and do the calibration running session outdoors.

  1. Log on to Polar Flow and go to Sport profiles.
  2. Choose Treadmill running and click Edit.
  3. Go to GPS and altitude and set the GPS recording rate to High accuracy.
  4. Click Save and sync the changes to your watch.


  1. Go outdoors and away from any tall buildings or trees.
  2. Enter the pre-training mode and choose Start training.
  3. Browse to the Treadmill running sport profile.
  4. Wait for the watch to find the GPS signal and then wait another 30 seconds to make sure that the watch catches as many satellites as possible.
  5. Start the training session.
  6. Run a distance of at least 500 meters, keeping a steady pace (at least 7 km/h or 8.56 min/km). Make sure that there is no ascent or descent greater than 30 meters on your route.
  7. Stop the training session and save it.
  8. Repeat steps 2 to 7 to save another training session to calibrate the stride sensor properly for indoor running.

After calibration, turn GPS off in the Treadmill running sport profile in Polar Flow and sync the changes to your watch. Now you've calibrated the stride sensor for treadmill running.









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