Incorrect mileage and calories for outdoor biking

[Jf1234]

 Hi. I recently got a Fitbit and I like it very much. However I am having some issues with biking. In bike mode it under reports my mileage by about 20%. I read an article from someone in your company to try it in run mode. But then it under report my mileage by 50%. I am comparing it against my bike computer and a fitness app on my phone, both are in agreement and Fitbit under reports it.

two days ago I rode 15 miles in Fitbit reported it at 13 miles with 700 cal burned. Today I rode faster and rode for 18 1/4 miles and fit it recorded it as 14 miles with a slower average speed and only 700 cal burned despite it being a longer ride

I’m concerned that the Fitbit is not accurate at all, and therefore useless. 

Suggestions? Thanks!

Moderator edit: subject for clarity

[LiliyaFitbit]

Welcome to the Fitbit Community, @Jf1234. I am sorry for the delayed response.

I am sorry to hear that your Fitbit device is not recording your distance and calories accurately for the outdoor biking. Thanks for trying to resolve this, I totally understand how you are feeling as you like the device and would like to track your activity accurately, I am here to help. If you are tracking your activity with GPS, I would recommend checking out this article with information about the different factors that can affect connected GPS.

In addition, you can perform a restart to your tracker by following these instructions.

If you haven't used connected GPS, please make sure your personal information is correct. For more information about the accuracy of Fitbit devices, see How accurate are Fitbit devices?

Let me know how it goes, I'll be around.