Charge 3 distance information inaccurate

[EmilySnebbers]

I've tracked most of my runs with 2-3 tracking methods at a time. My most recent run was completed with phone GPS on the Fitbit app, Charge 3, and Runkeeper. In the past, I've compared with Strava which gives a similar disparity below.

Fitbit app distance: 1.89 miles

Charge with map reported in app/waited until it vibrated confirming connection to phone GPS): 2.61 miles

Runkeeper: 2.06

Most consistently my results are:

Charge 3 reports the highest/fastest values, but typically closer to the third party app, and Fitbit app will underestimate distance by typically one half mile, increasing with longer runs.

I don't know the exact values of the paths, but maybe I'll give the roads a drive around. It surprises me that the Fitbit app and the device are so far apart when they are using the same GPS signal. I run with my phone attached to the same arm as the device. Is there a way to get these to sync?

Moderator Edit: Clarified subject

[AlejandraFitbit]

Welcome to the Forums, @EmilySnebbers.

Thanks for the information provided. Fitbit devices calculate distance based on the device’s accelerometer data and stride length setting.

Default stride length is based on your height and gender. If available, Fitbit devices use GPS data to calculate more precise distances.When you sync your device, our algorithm interprets the data from the device, and you see your distance traveled in the Fitbit app. 

Note that when you track an exercise with GPS, both GPS and accelerometer data are used to calculate the distance shown in the Fitbit app. For more information about accuracy, check the article: How accurate are Fitbit devices?.

Let me know the outcome. 😉