Distance is inaccurate while walking.

[Walker1836]

I checked my reported Blaze walking distance and found it about 33% low.  I am concerned about this.  My cheap single axis pedometer is much more accurate.  I know my walking stride length is correct.

What I did to check the Blaze was to use Google maps to find an address on my usual walking route exactly 1.5 miles away.  Then I walked to it and checked the change in step count and distance.  Just for reference I checked it with various other instruments.  I used the same stride length (28 inches) with both the Fitbit and the Pedometer.  Units below in miles:

Fitbit GPS app:  1.54 miles

Single Axis Pedometer:    1.44 miles

Garmin GPS:    1.48 miles

Fitbit Blaze:   (2524 steps X 28in) / (12in/ft *5280 ft/mi) = 1.11 miles

I think the Blaze might be using my running stride length when I am walking. My walking speed is 3.2 mph.  How can I fix this?

 Moderator edit: Updated title for clarity

[Rich_Laue]

My question would be, how was the step count accuracy @Walker1836?

 You say the Blaze reported distance was short but there is no mention of what the blaze had reported. 33% short would be a reading of 1.00 miles. The Fitbit GPS is 1.54 Willie is not short but over and still within the 5% Fitbit claims.

1.5 miles and if you took 2524 steps the stride would be 38 inches that is why I'm asking if your steps where calculated correctly? Yes I can also do the math having a degree in statistics, but at 12:30 in to lazy.

[Walker1836]

2524 was the change in stepcount over the 1.5 mile distance.  With a stride length of 28.1 inches this calculates to a distance of 1.12 miles.  33% low.

Based on suggestions from previous reports of inaccurate (low) walking step counts in the forums I repeated this 1.5 mile walk with the Blaze in my shirt pocket.  The change in step count in this case was 3151.  This calculates to 1.40 mile with an 28.1 inch stride.  This matched the Blaze's reported change in distance perfectly for an 18.1 inch stride but is low about 7% for the true distance.  This is OK for my purposes, although my $5 single axis pedometer counts better.  Reference my original post.

I walked back over this same distance with the Blaze on my wrist.  I tightened the strap as much as I could and tried to swing that arm naturally.  The step count change was 2774 (1.23 miles) or about 18% low.  An improvement, but not good.

Obviously there is a problem with the accelerometers or the measuring algorithm.  Do you know which it is?  Can it be fixed?  Is there an update that can improve this?

[Rich_Laue]

I'm wondering if your using the auto walk detect function or manually starting the recording by putting the watch into it's walk mode?

If when taking a walk, counting off 100, 200, 500 steps what does the tracker

YourYo not pushing a stroller are you? 

[Walker1836]

Rich,

I am manually (i.e. with a #2 pencil) recording before and after step counts and distances (miles) and then taking the difference.  I believe my Blaze is in autodetect mode for walking because it does seem to accurately note the time of my walks.  I am not taking step counts from this function.

I am not pushing a stroller, but I am carrying a goose gun.  (just kidding)

[Kbkat]

I entered basically the same problem but admin deleted my post without answering it.  I dont think they ca re e if the product is accurate.

[Rich_Laue]

So when you get your stats, are they from the recorded walk, or from the numbers directly from he tracker. I thought we have been talking about a recorded walk that show up in your exercise, but auto detect will not give a distance total.

Before we can determine the accuracy of distance, we need to determine the accuracy of steps. Your tracker in the mode your issuing it, can not measure distance, but needs to take an educated, calculated guess. If the speed of the walk is changed so will the users stride.

I first tested the step count, then did 5 days of walks to determine an average stride, then set my stride to this average. 

[Walker1836]

I am using step count and distance values directly from the tracker.  My stride (28.1 inches) was calculated by Fitbit from my height.  It matches quite well with the 28 inches I have used with my old pedometer with good accuracy for years.  I initially determined that from counting steps from goal line to goal line on a football field. It is pretty close.  Much closer than 20-30% error I am getting.

[Kbkat]

In tracking mode..nothing happens or is recorded unless I physically take my phone out of my pocket and open the app.  If I chose to not track the mileage but wear my Fitbit and just let it auto detect, it shorts me a minimum of half a mile.  I know this because I walk the exact same walk everyday and prior to November 1 it was working in either mode.  Now in neither


Sent from my Galaxy Tab® E

[Rich_Laue]

@Walker1836 in completely confused when walking from goal to goal your step count is correct? I'm not sure where the stride comes in here. Yes I know your using the step count from the tracker, but is the tracker counting your steps correctly?

@Kbkat with the blaze you can leave your phone and the blaze will track your steps and walk, minus the map.

In auto detect the Blaze will track time, steps, and calories. With auto detection the blaze does not track distance, therefore if using the auto detect your distance will not be of by a half mile because the Fitbit doesn't record the miles.

Notice in my week all these walks when auto detected and no distance has been recorded.

 Seeing that you both say that you use the auto detect function and Fitbit is reporting the wrong distance, I would like to know how your doing what?

Since distance is bad on the steps counted by the Fitbit I'm also curious if you walk 200 steps, does the Fitbit count 200 steps. If Fitbit is having trouble counting steps or the steos de setting ng is off, so will be there distance. 

[Kbkat]

I beg to differ. When I start I note my miles. When I finish I get my
synced miles and it's off by at least half a mile

[Rich_Laue]

@Kbkat if that is what your doing then your not depending on the Fitbit tracker to auto detect your walk, you're simply manually making a note. In this case either Fitbit is not counting the steps correctly, or the stride setting is off. Fitbit will not measure distance in your case, it takes Steps counted and multiples this number by the distance per step.

Let's say the stride is correct at 30 inches and Fitbit says the walk took 2200 steps, this would be a fitbit distance of 1.04 miles. However we know the true distance was 1.5 miles. Something die not match up, we first want to check the steps counted.

Write down the starting number.

Now start walking with the left foot, count every right step.

Stop at 100, since you only counted every other step, the true count would be 200.

Does the tracker show that 200 steps where counted?

If the tracker counted the steps correctly, then we now know the stride setting is not correct.

Looking at your posting history, I see that your having problems with the blaze and voice cues, that is because the Blaze does not have a speaker and is unable to give voice cues. If you want voice cues, you will need to manually start the walk with the Fitbit app, not the Blaze. 

[Kbkat]

I always start with the app when I track. It used to c as ll out the half
miles accurately. The first of November it stopped working. I changed
nothing..nads

[Walker1836]

Rich,

I apologize. The error in step count and distance is with the watch not the tracker.  I am noting step count and distance on the "today" screen.  I then walk a known distance and compare this with the change in steps and distance on the watch. 

At lunch I often walk 2 laps of a .9 mile loop.  I have verified this distance with my Garmin GPS and Fitbit GPS.  If I get a chance, I will walk this today and record the values.  I'll do one lap with the watch on my wrist and one with it in my pocket.

I know my stride length is correct from previous measurement and experience. It also closely matches the Fitbit default value for my height.

[Rich_Laue · Accepted solution]

---

@Kbkat wrote:
I always start with the app when I track. It used to c as ll out the half
miles accurately. The first of November it stopped working. I changed
nothing..nads

 I beg to differ. When I start I note my miles. When I finish I get my
synced miles and it's off by at least half a mile

---

These two quotes above contradict each other.

Starting with the app is using the phone's GPS to record the distance. In this case only the step count, heart rate, and calories come from the tracker. Your stride setting should be irrelevant.

When the miles are noted during the beginning and the end of the walk , this number comes from the tracker and GPS is not used. Step count and stride must be accurate, still looking forward to the result of the step count test.

@Walker1836 if you are absolutely sure the stride setting is correct, and the distance is off, then the the steps counted by the Blaze is wrong. It is very simple steps times stride equals distance.  What was the result of your step count test? 

[Walker1836]

Rich

Yesterday I walked the nominal .9 mile loop twice.  The distance changes were:

With Blaze on wrist: .79 miles

With Blaze in shirt pocket: .80 miles

Today I performed your "200 step" test twice:

start: 3569 finish: 3767 difference: 198

start: 3767 finish: 3973 difference: 206

No missed steps!

I also did another 2 laps on the nominal .9 mile loop. 

Lap1:

Blaze:  .81 miles

Single Axis Pedometer:  .79

Garmin GPS Trip Computer:  .86 miles

Lap2:

Blaze:  .79 miles

Single Axis Pedometer:  .81 miles

Garmin GPS Trip Computer:  .86 miles

I think the Garmin is probably closest to being correct.  I don't know why I was coming up so short the first few days with the Blaze...  I am wearing it tighter than I was, and I now move it a little higher on my arm for a snugger fit while walking.  Or maybe sunspots...

My conclusions:

The Fitbit Blaze is not missing any steps.

The Fitbit Blaze is quite consistent.

If I slightly increase my stride length used by the Blaze, the claimed 5% accuracy could be achieved.

Rich_Laue is a smart and useful fellow.

[Rich_Laue]

Glad things are about to be dialed in.

Try this formula @Walker1836

TrueStride = CurrentStrideSetting * (TrueDistance/Fitbit reported distance)

You may want to do this on several days to get an average 

Simply treat the individual days as one walk. As the total Fitbit distances and the total walked distance and use these figures. 

[Walker1836]

I guess I spoke too soon.  I changed my stride length in both the Blaze and Pedometer per your formula and went on a 3 mile walk (1,5 out, 1.5 Back):

Outbound:

Garmin GPS: 1.52 miles

Blaze:  .95 miles

Single Axis Pedometer:  1.48

Inbound:

Garmin GPS: 1.45 miles

Blaze:  1.09 miles

Single Axis Pedometer:  1.55 miles

The only thing different from when it worked OK on wed as I was walking on pavement (instead of a cinder track)  and I had a water bottle in my dominant hand this time.  Blaze was on the other wrist.

I will do the step counting routine again and the shirt pocket thing again and with and without the bottle.

I never give up.  I am thinking my walking movement is not to Blaze's liking or maybe the wrist is not the place to mount accelerometers to accurately detect steps.  

[Kbkat]

I appreciate the help trying to solve my problem. Everyone has been
concentrating on stride length. If I dont care about the number of steps,
only total miles, why does stride length matter. I'm using gps, which
should be the same distance every time. Also, what explains the fact that
it works perfectly and then it doesnt. I've not changed anything

[Rich_Laue]

Until we get confermation from Fitbit that GPS is used during a manually recorded walk to record distance, considering that several people, and me, have proven that Fitbit has not done so on the Blaze in the past, I'm going to say that the stride setting does matter.

Fitbit comes right out in the user manual saying GPS during a run recording is use for run. They do not say this about a recorded walk.