For the past couple of years I have been tracking my Steps and Walking Distance with my iPhone’s Health app on my daily walks. At first it seemed like the routes I set for my morning walk and afternoon walk came in pretty consistently at a total of approximately 3 miles and somewhere around 8000+ steps.
However, over time, it seemed like taking the same walks would come in as anywhere from 2.4 to 2.8 miles. Checking my Walking Step Length, those would sometimes be, say, 16.9" or on up to 22". As an experiment, it sometimes seemed like if I took longer strides up and down my hallway, I could raise my step length average, which seemed to up my walking distance.
Does anyone here understand how the calculations of the Health app work? Has the accuracy of the app gotten better over time or is it all just an approximate crap shoot?
I would say mine are stable. I walk a lot and AFAICT it judges that accurately, based on comparison with my Garmin running watch or maps data. However, I also know that when my wife and I hike together (and we do that a lot), her walking distance always ends up showing less than mine. The only systematic difference I’m aware of is that my iPhone is usually tucked into my pants’ front pocket, whereas she usually carries her iPhone in a purse or backpack, but almost never directly on her.
I’d say if iPhones rely on internal motion sensors when measuring distance traveled, not GPS readings, in the manner of traditional mechanical pedometers, the variability is to be expected. Also, if altering one’s stride has an immediate effect—especially in a physical location with limited GPS connectivity such as an interior hallway—it seems even less likely GPS is involved.
Although it’s been a while since I bothered checking Health stats like walking distance, I have found that the numbers can vary dramatically depending on where my phone is at the time (e.g. in a pocket, on my belt, or being used in my hand).
And when taking a long walk with my wife (who has her own phone and a Watch), her stats will differ significantly from mine.
It is very inaccurate at times. It frequently has trouble with flights of stairs. I gave up on having it calculate distance, as that was frequently off. Now I just track number of steps, which is more accurately “Number of Steps with Phone in my Pocket”, and flights of stairs, with the latter being right on some days and wildly wrong on others. Sometimes it throws in phantom stairs.
FWIW, I always have my iPhone in my left pants pocket on my walks, so that is generally not a variable. I think that from here on, I will just assume that the Health stats are on par with the Weather predictions, i.e. sometimes more accurate than other times. Being constantly fed tidbits of data by our phones and computers gives us the impression that things are being measured accurately down to the decimal point. Perhaps it is more the case that computational devices are designed to provide a highly specific answer, even when the data is an average or a guess.
Thanks for the links. Based on the info they provide, I appear to have the relevant settings set on my iPhone, but not having an Apple watch, I can’t fine-tune the pedometer, etc. Oh well.
I find that the pool swim Workout function is hit and miss. I regularly swim 40 lengths and the Apple Watch usually thinks it is less than this. I guess it is trying to sense and count turns since it doesn’t know what type of swimming stroke I am doing.
As an aside, the Workout app incorrectly describes a (pool) length as a lap. A lap is when you return to the starting point - two lengths in a swimming pool.
Actually, most swimming competitive organizations consider the two to be the same. Different from a “lap” at a track meet, where it means a return to the starting point. But not everybody agrees.
FWIW, when I was taking swimming classes as a kid, my instructor considered a lap to be a single length. But I didn’t know that and thought it was like a track-lap, so I ended up swimming twice the distance he was asking me to swim.
My step counts are stable, using an iPhone XS stored alone in my trouser front right pocket.
I also track with:
Amazfit activity band on my left wrist (the same as iPhone, within very small margin of error)
Nintendo pedometer in my left front trouser pocket, with coins and wallet (always about 10–15% higher which I’m ok with because I use the step count in a game!)
One interesting anomaly I discovered when on a cruise on a relatively small ship. I noticed that when I had walked about two times all the way around the ship, my Apple Watch said I had walked a mile. That confused me, until I realized that no doubt what was happening was that it was measuring both the distance I had walked plus the distance the ship had travelled. Even when walking toward the rear, since the ship was travelling a good bit faster than I was walking, I was getting a positive distance reading, not a cancelling out.
