Fitbit Inspire is not accurate

[Poppa57]

I have just started using a Fitbit Inspire (not HR) and it seems to be giving me inaccurate results.

My previous tracker, a cheap $30 (non Fitbit) offering gave me 3,557 steps and 1.6 miles on my walk this morning.

The Fitbit gave 4,048 steps and 1.96 miles.

I calibrated my previous tracker by counting my steps and by comparing the distance by checking it against Google Maps and MapMyWalk so I am confident that it is accurate.

Why is the Fitbit exaggerating the length of my walk?

I did not expect them to give precisely the same figures but this seems to be rather a large difference.

[Rich_Laue]

Was your $30 unit on your wrist? Or clipped to the waist? 

Have you worn the two during the same walk? 

Your stride on the $30 is set for 2.37 feet, with Fitbit you have set the stride for 2.47. 

[Poppa57]

Thank you for the reply.

Q1 - Both were on my right wrist in the same position.

Q2 - Yes, and both were on my right wrist next to each other.

Q3 - My stride length on my old unit is 29 inches (2.42 feet).  I hove now set the Fitbit to be 29, but I cannot recall whether I did this before my walk earlier and I am also not sure what the default value that the Fitbit set as my stride length.  (31.? rings a bell.)

Do you know whether the Fitbit measures the number of strides and calculates the distance from that and the stride length, or measures the distance travelled and then calculates the steps?

[Rich_Laue]

Fitbit normally counts steps, looks at the stride setting and takes a calculated guess on the steps. Without GPS Fitbit has no way to measure distance. 

If a user uses the mobile track without the Fitbit tracker, Fitbit uses the phones gps to measure distance, and the users stride to guess at the steps. 

[Poppa57]

To Rich_laue:

Thanks for the reply, but please could you explain what you mean by "If a user uses the mobile track without the Fitbit tracker,"

Thanks.

[Rich_Laue]

How do I use Fitbit MobileTrack?

Mobile track is a feature that allows a cell phone to take the place of a Fitbit tracker when the tracker was left home. Or being charged. 

[Poppa57]

I don't think I am using that feature.

How does the device know how many steps I take?  Surely it can only do that by measuring the distance I travel and divide by my stride length.

I am sure it would make life easier for all concerned if the documentation had a bit more information about how the thing worked.

[Rich_Laue]

@Poppa57 mobile track is an option found in the Fitbit app if the phone has supporting hardware. It would show up under the device list. 

The Inspire has accelerometers that detect changes in speed and uses this data to determine what movements the arm is making. When Fitbit determines that the arm movements are the ones made while a person is stepping. Fitbit will count the steps. 

Fitbit then multiplies the steps by the stride setting to take a guess at the distance. 

Have you read the user manual or browsed the interactive, searchable help docs? Link to this help found below, choose your tracks and the next page has a link to your user manual 

[Poppa57]

Thanks for the reply, but my device is already packed up ready to be returned.  After spending about a week trying to get it working, today it stopped syncing.  It took me about 30 minutes to reset the device and get it syncing again.  It was at that point that I admitted defeat and decided to send it back on the grounds that I am spending time trying to get it working when I could be exercising.

Just for the record, you said "When Fitbit determines that the arm movements are the ones made while a person is stepping."  Sorry, but I don't believe that.  This morning I walked for about 10 minutes carrying a large box so my hands were stationary relative to my body.  It still calculated the steps reasonably accurately.  Based on using a tracker for two years I believe that it uses GPS to measure how far you have travelled and calculates the steps from your stride length.  (But I would dearly like to see a document that actually states how it is done.)

It has been an interesting week but I will return to using my old tracker.