GPS and HR accuracy while running

[HephNZ]

Previously I had a MS Band device but had to replace it with the Fitbit Blaze.

I've been happy enough with the Fitbit (syncing is painful at best, and the data presentation is rudimentary, but it does the job)

My issue is that the connected GPS distance and HR are wildly inaccurate when jogging.

Just this morning I went on my usual 5.2KM run, at my usual pace. 

At the halfway point (2.5KM previously measured by car, the Fitbit passed 4KM.

By the time I got home and synced, the full run clocked in at 7KM, well over the correct 5.2KM and not even the same distance for the first and 2nd half.

In addition, my HR whenever I looked at the Blaze didn't go above 130bpm, I did try wearing it various ways to see if it made a difference, but it didn't.

Funny thing is when I synced the Blaze later the app shows that my heart rate was never as low as 130bpm (except at the start and end of the run).

So my question: Why is the actual Fitbit device data being shown so inaccurate?

It's great to have a look at the stats after the run but as it is it offers no value when actually exercising

Am I just expect too much from the device?

[AlejandraFitbit]

It's great to welcome you @HephNZ. Regarding to your KM information, I recommend measuring your stride length by following the instructions provided in this post, I know that the Blaze has this feature but it would be better if you can measure it manually. After this, go for a run and test your tracker. Now about the heart rate information, take a look at this post, where you will be able to find some things that might be causing discrepancies and tips to fix it.

I hope this helps, catch you later.