iPhone SE How can the Health Activity App be slo wrong?

cheddar-caveman

macrumors regular
Original poster
Oct 25, 2012
157
20
My wife and I have just come back from a 6 mile walk and her Activity monitor said 8.3Km (5.1 mile) while mine said 10.2Km (6.1 mile).
How can they be so different/wrong? How is the App "calibrated?
 

jtara

macrumors 68000
Mar 23, 2009
1,957
509
Do you both have the same phone model? Same watch model? (You didn't say if either of you have a watch.)

Did you both use the Workout app, and start a Workout, at the same time? Or did you just rely on the default activity monitoring? Activity monitoring will try to guess when you are "exercising" or not, and will record ALL movement. Heck, I record at least a mile a day inside my apartment!

I believe there is some initial calibration - sorry, it's been a long time! I think the first time you use Workout to go on a walk or run, it will compare GPS data with accelerometer data to estimate your stride.

FWIW, this discussion would go better in "iOS Apps" than in "iPhone"/"iPhone SE".
 

Minimalist00

Suspended
Feb 11, 2019
14
18
It sounds like your watch was fairly accurate at 6.1mi for a 6mi walk, where your wife’s activity monitor fell short.
 

cheddar-caveman

macrumors regular
Original poster
Oct 25, 2012
157
20
Sorry, left a bit of info out there.
Both have an iPhone SE and yes mine seemed to be fairly accurate.
The app is built into the iPhone under "Health" but there is no way to actually calibrate it yourself, let it know how long your average pace is and obviously it falls a bit short.
IMG_5503.jpg
 

ttforever

macrumors regular
Aug 13, 2015
154
49
Check that motion calibration and distance is turned on in the privacy/location services/system services is on on both phones that calibrates stride length etc.
 
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OBirder

macrumors 6502
May 13, 2015
362
255
Sorry, left a bit of info out there.
Both have an iPhone SE and yes mine seemed to be fairly accurate.
The app is built into the iPhone under "Health" but there is no way to actually calibrate it yourself, let it know how long your average pace is and obviously it falls a bit short. View attachment 821370
There is not enough information to judge this. You haven’t told us how you know the accuracy of the length of your walk.
How are the both of you carrying their phone?

It counts the activity of the whole day (since midnight) and not just your walk. Your screen print shows past 9 PM.
At 9 PM I doubt that your walk was 6 Miles.

You could check details by clicking on Walking+Running Distance -> Show All Data -> Select the data you want to compare.
You can further click on each entry to see the start and end time and distance.
But it will be a daunting task to compare.

I would recommend that you use an App that allows you to start and stop a walk to compare.
 

ftaok

macrumors 603
Jan 23, 2002
6,201
1,221
East Coast
Quick items to check.

1. Do you have your height, weight and gender set correctly on the iPhones? If the phone isn't using the GPS, it will use your height/weight/gender to estimate your stride length and multiply that with the steps counted.

2. Make sure all of the GPS related functions/settings are turned on.

3. Use an app to track your workouts. Something like Endomondo.
 

bransoj

macrumors 65816
Jul 31, 2013
1,045
269
I use a fitbit these days but even so that is still not 100% accurate, its fine as a guide to steps\distance etc and handy as its just basically a watch on my wrist but if i'm doing a walk that i want to know how far i've gone more accurately i'll use either the walk function on my Fitbit that combines with the GPS on my phone or use Runkeeper which is a free app that again uses GPS to track your activity and then keeps a record of your activity for you to look back on if you wish.

Whilst the pedometer function of the iPhone is handy there are too many variables that are involved for its step count and distance to be 100% accurate. If my wife and I go out for a walk with the dog we have identical fitbits set up the same with our heights etc and still end up with slight different read outs and if you start pushing a pram it completely confuses it into thinking you are riding a bike sometimes!!:rolleyes:
 

Plett

macrumors 6502
Feb 16, 2016
296
217
Make sure location is turned on. If one is using GPS and the other is not that would explain the issue. It is not like a mechanical pedometer, although it can work that way and make assumptions if it cannot rely on the internal GPS.
 

ftaok

macrumors 603
Jan 23, 2002
6,201
1,221
East Coast
Make sure location is turned on. If one is using GPS and the other is not that would explain the issue. It is not like a mechanical pedometer, although it can work that way and make assumptions if it cannot rely on the internal GPS.
I don't believe the iPhone will use the GPS on it's own. It needs an app to request the use of the GPS. The iPhone alone does not have a Workout app like the AppleWatch.

The OP indicated that both he and his wife are using the iPhone with an AW (or other fitness tracker). Therefore, unless he's using a 3rd party app, the GPS is not in play.

The solution would be to use an app that can request the use of the GPS. Endomondo works for sure, but some may be put-off by the constant nagging to "go pro". I'm sure there are other apps that can track an outdoor walk.

Note, most apps, once calibrated via the GPS, can handle indoor walks and treadmill walks pretty accurately.
 

Plett

macrumors 6502
Feb 16, 2016
296
217
I don't believe the iPhone will use the GPS on it's own. It needs an app to request the use of the GPS. The iPhone alone does not have a Workout app like the AppleWatch.

The OP indicated that both he and his wife are using the iPhone with an AW (or other fitness tracker). Therefore, unless he's using a 3rd party app, the GPS is not in play.

The solution would be to use an app that can request the use of the GPS. Endomondo works for sure, but some may be put-off by the constant nagging to "go pro". I'm sure there are other apps that can track an outdoor walk.

Note, most apps, once calibrated via the GPS, can handle indoor walks and treadmill walks pretty accurately.
Distance is measured with the GPS not the step count. The 3 axis accelerometer measures steps. The phone doesn't need an additional app for this functionality. In location services the Motion Calibration feature is there for that reason.
 

cheddar-caveman

macrumors regular
Original poster
Oct 25, 2012
157
20
Interesting reading all the ideas, thanks a lot.
I can see there are too many variables for two people to ever get the same readings. Of course the daily measurement is from midnight to midnight, you cannot reset it to when you actually start the walk.
 

ImAnAgent

Suspended
Oct 11, 2018
273
211
My mind
There are times where I wore two watches (last winter, the entire winter) and went out on my usual 5 mile walk. Each watch was paired to a separate iPhone. They have varied by as much as 1500 steps so I have come to the conclusion that no two watches will ever measure the same even if it's to walk the the same route every single day. it's just impossible.

Calorie counts were also off by sometimes 50-100. The watch on my right hand would usually count more steps and more calories because I am right handed.
 

now i see it

macrumors 603
Jan 2, 2002
5,190
10,533
On your next walk together, carry both phones on you (carry hers) and see what they say at the end. If they record the same distance then that's telling you that the Health App distance recording method isn't very accurate.

Personally I found the health app to be too inaccurate. To the point that I never use it any more. It can't even count steps accurately no matter how you carry the phone.

It's best used as a measuring stick against itself. It's fairly repeatable, just not accurate (in my experience).

Although many may disagree with this statement, personally, I think the Health app is junk. It far too inaccurate to be worth using (in my experience).
 

MEJHarrison

macrumors 65816
Feb 2, 2009
1,437
1,485
My boss told me of similar findings last year. Her boyfriend got way more credit than she did for the event they were attending. They finally decided is came down her holding his hand (their guess). She had her watch on the arm that was holding his hand. His was on the opposite arm swinging freely.

Not sure if there's a lot of truth to that story or not. But I thought I'd at least mention it.
 
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