Map my Run disagrees with Fitbit

[SunsetRunner]

I have read a few similar threads, but I haven't found a real explanation of my issue, which is a discrepancy between Map My Run and the Fitbit app...specifically in distance. MMR logged my morning walk at 3.62 miles this morning. My dashboard, however, only recorded 2.86 miles. The time was about the same, but there is a pretty big discrepancy between distance and pace. I have a Charge HR.
I am also not clear on whether there is a need to activate the activity mode when I log my workout with MMR. I would appreciate any thoughts on this.

[Motherrunner424]

I have a Charge 2 and an LG phone.

When I use MMR and Fitbit at the same time, with Under Armour Sonic 2 shoes connected for MMR, there is an almost 5 minute difference between my MMR time and my fitbit time for 3.1 miles. MMR is consistently faster and more accurate based on the measured track I run. Also, according to the image of my run on Fitbit, I strayed well off the course several times (I didn't.) It is incredibly frustrating and I'm seriously considering switching back to my Garmin because fitbit STILL hasn't answered the root cause! 

[brandonvmoore]

Yeah, I've pretty much accepted that Fitbit isn't for people who want great
accuracy. But for me I more or less just think of the results as "units"
and am more concerned with comparing day to day results so while it's
certainly disappointing, I don't care enough to go buy multiple other
devices that are more accurate but don't do everything this does.

[Rahela9]

I don’t trust Fitbit steps because my arm movements will record as a step and I’m sitting down. 

[Rich_Laue]

Have you checked your hand setting @Rahela9 changing it to dominate even if it is on your non dominate arm may be helpful. 

Yes you are correct, the tracker is in your arm and looking for the type of arm movements that happen when the feet are walking. It does not directly monitor your footsteps.. While Fitbit frequently revise and tune the algorithm, just like every other arm based step counter on the market, at times it does get tricked. A user may lose or gain a few steps. It averages out. 

[JasonNazworth]

If you want accuracy, stick to a GPS fitness device. Garmin is pricey, but
worth it.

[amandagosling]

I'm getting the same problem. I know from running with my phone that i do a just sub 10 minute mile but my fit bit (charge 3) is telling me I am doing a 10:50 min mile (even at a heart rate of 160 odd). GPS is turned on 

[brandonvmoore]

That's not unusual. Most people are right handed and wear their fitbit on
the left (non-dominant) hand so the additional steps recorded like this are
pretty minimal and insignificant. However, if you have placed the fitbit on
your dominant hand then it will record steps when you are just writing and
doing things like that. There is a setting you can turn on to let it know
you have it on your dominant hand and, I assume, this helps prevent those
steps from being recorded.

However, you should keep in mind that the fitbit is a pedometer and not a
super sophisticated robot with perfect AI watching your entire body to see
when you take steps. There are a lot of movements you take that are
recorded as steps even though they are not, and in my opinion SHOULD be
recorded as steps. If you are hitting a punching bag, for example, those
movements should and do count as steps.

[AlvaroFitbit]

Hello everyone. Thank you for sharing your experience tracking your distance with your Fitbit device. If you wish to improve the distance calculation you can measure your stride length and enter it on your account information. Additionally if you use the GPS feature you can follow these suggestions to improve the signal reception.

Let me know how it goes.

[Volson]

Interesting that FitBit always tracks my runs 0.2-.0.3 miles longer than MMR.