Accuracy of gps

Hi e7andy. Yes auto pause is off. 

My GPS setting is GPS only.

There are two other settings, GPS +Glonass & GPS+Galileo however not sure what difference they'll make.

My only other thoughts are, could the distance given via Ordenance Survey app take into account the terrain covered. Whereby the Garmin records a distance based on a flat terrain.

Hmmm. It would be nice if someone from Garmin new the answer

Garmin uses an algorithm mixing GPS and accelerometer data to estimate the distance and pace. Unfortunately the algorithm is far to be perfect.

The accelerometer (+ gyro, if available) data may come either from the internal sensors, or from external ones (for example the HRM-Pro chest strap). The accuracy depends quite a bit on the history of your activities, and how well the accelerometer is calibrated. Unfortunately, there is no way to reset, stop, or restart the calibration when using the internal sensor. That is only possible with some of the external sensors (for example with the already mentioned HRM-Pro).

Based on my personal experience, the distance and pace accuracy may deviate up to some 10% (or even more) of the true distance with the internal sensor. The accuracy is much better with the HRM-Pro - typically around ~1%. That's at running, walking, and at swimming. At cycling, the accuracy is much better even when using just the internal sensor.

Apart from using a compatible external sensor, currently the only way to get the distance right, is editing it manually after each activity. Getting the true distance, based on the GPS data, can be done for example through Strava, by using its feature "Correct Distance", or by saving the activity as Course.

You can also try performing the master Rest of the watch with deleting all data, and then reconfiguring it anew, hoping the watch will recalibrate the accelerometer pace/distance estimates better this time.

Eddie3625 said:

It would be nice if someone from Garmin new the answer

It does not happen very often here on the forum. You may have a better chance when asking them directly through their Support website at https://support.garmin.com, however I am afraid that the average suport person will just present you with a canned answer, not even explaining the details mentioned in this post. In the best case they will offer you a replacement device, which will behave in the same way, and unless you are luckier with the calibration of the new device, the results won't be accurate again.

Thanks Trux, after reading your reply I went out yesterday for a walk and recorded the distance covered via the Strava and Ordenance Survey app. I also set my Garmin off at the same time changing my GPS to GPS plus Galileo.

On return both the Strava and Ordenance Survey recorded the exact same distance of 3.4 mile with the Garmin recording 3.11 mile. Obviously the longer the walk the greater the discrepancy. So from now on I'll use either Strava or the OS app for recording my walks and the Garmin for other types of monitoring.

Thanks again

If you want to keep the metric in Garmin Connect correct, I recommend to continue using Garmin for everything. Simply link your Garmin Connect account with Strava, and when the activity is synced to Strava, enable the "Distance Correction" at Strava (I think it is only available on the web interface). When done, copy the distance from Strava and paste it into Garmin Connect (open the activity there and select Edit).

Cheers Trux, I'll look into that