Tracking distance

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Alexandra_Faller
Alexandra_Faller Posts: 25 Member
in Fitness and Exercise
I go for a walk every morning on the same route. I have a garmin vivosmart hr, Apple Watch and iPhone with map my walk.
All three say I have walked different distances, the map my walk says it's 4.18km, the Apple Watch says 3.67km and the garmin says 3.28km.
Quite a difference. I assume the garmin is way off due to stride length but Which one would be the more accurate so I can track using that instead of all three?

I would assume the gps map my walk but I'd rather get other people's views first as I don't want to think I'm walking further than I actually am.

Replies

  • Machka9
    Machka9 Posts: 24,922 Member
    edited April 2017
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    I use Strava.

    From a cycling perspective, Strava matches Ride With GPS and Google Maps ... so I figure it's probably reasonably accurate.
  • malibu927
    malibu927 Posts: 17,565 Member
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    Apple Watch, most likely. The signal of your phone can jump around and give you a crazy map, or at least it does for me with Runkeeper.
  • Alexandra_Faller
    Alexandra_Faller Posts: 25 Member
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    malibu927 wrote: »
    Apple Watch, most likely. The signal of your phone can jump around and give you a crazy map, or at least it does for me with Runkeeper.
    Thank you I'll use the Apple Watch data :)
  • dpwellman
    dpwellman Posts: 3,271 Member
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    The MapMyFitness applications (MapMyRun) using on phone was fairly accurate when I used it last. My TomTom Multisport is dead accurate on the Atlantic coast.

    What causes accuracy discrepancies with GPS tracking are two things: sample rate and elevation compensation. Step counters for distance (or anything useful) are woefully inaccurate.
  • TimothyFish
    TimothyFish Posts: 4,925 Member
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    MapMyWalk will probably be the most accurate of the three. I know that when I was using MapMyRide the app was coming very close to the distance I was getting from a cyclocomputer that was measuring distance by counting the revolutions of a bicycle wheel.
  • deannalfisher
    deannalfisher Posts: 5,600 Member
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    I had the mapmyrun/ride/walk apps - they tried telling once that my 20mile bike ride (marked) was only 5miles (I was running strava at the same time which gave me the correct distance)

    also commercial GPS have an accuracy to within .5 of a mile, depending on which satellites are used to triangulate and how many are used in the fix (standard is 3, but sometimes it could be more);

    it also depends on if they calculate their distance using straight line measurements or follow the path
  • TimothyFish
    TimothyFish Posts: 4,925 Member
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    deannalfisher wrote: »
    I had the mapmyrun/ride/walk apps - they tried telling once that my 20mile bike ride (marked) was only 5miles (I was running strava at the same time which gave me the correct distance)

    also commercial GPS have an accuracy to within .5 of a mile, depending on which satellites are used to triangulate and how many are used in the fix (standard is 3, but sometimes it could be more);

    it also depends on if they calculate their distance using straight line measurements or follow the path

    That's incorrect. Positioning accuracy on smart phones when GPS is available is 8 meters, which is 0.005 miles, not 0.5 miles. When positioning is based on the cell tower network instead of GPS, that accuracy may be as low as 600 meters or 0.37 miles, but that would only occur when line of sight between the smartphone and the satellite doesn't exist.
  • Bluepegasus
    Bluepegasus Posts: 333 Member
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    I personally find MapMyRun(same as mapmywalk) to be pretty accurate. Having used it in measured races, it's always within .5 of a mile.
  • Alexandra_Faller
    Alexandra_Faller Posts: 25 Member
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    Ok thank you so the consensus is that the app on phone tracking my walk would be most accurate.
  • lorrpb
    lorrpb Posts: 11,464 Member
    edited April 2017
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    The phone apps all are wildly inconsistent where I live. Sometimes very close and other times off by as much as 20%. 0.5 mile variance in a 5k or even 10k is a lot, IMO. Use all the devices over a known distance and see
    WHich is most accurate for you..
  • JetJaguar
    JetJaguar Posts: 801 Member
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    The Apple Watch would probably be the most accurate. For various technical reasons having to do with the chipset, and antenna design and placement, the GPS in a phone or smartwatch isn't going to be that accurate, but the watch would probably be best since it's antenna would have the clearest view of the sky. That's important with GPS, because the signal doesn't like passing through anything. Even running under a dense tree canopy can throw it off.

    For maximum accuracy, a dedicated GPS device like a Garmin Forerunner would be best. I have a Garmin on my bike and a Forerunner for running, and they are accurate enough for me to tell what side of the road I was on.
  • zdyb23456
    zdyb23456 Posts: 1,706 Member
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    I use Runkeeper on my phone and it seems pretty accurate. When I run the same route it's pretty consistent with same distance each time.
  • OldAssDude
    OldAssDude Posts: 1,436 Member
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    You should go somewhere that you can walk a known distance like a track or some place with mile markers. Then you can accurately test the devices to see which one is the most accurate.

    The most accurate devices I use are the Suunto Ambit 3 Peak and the Suunto Spartan Ultra, but they are very expensive devices. They have pretty accurate GPS's and also monitor and calculate advanced metrics for exercising.
  • AnvilHead
    AnvilHead Posts: 18,344 Member
    edited April 2017
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    deannalfisher wrote: »
    I had the mapmyrun/ride/walk apps - they tried telling once that my 20mile bike ride (marked) was only 5miles (I was running strava at the same time which gave me the correct distance)

    also commercial GPS have an accuracy to within .5 of a mile, depending on which satellites are used to triangulate and how many are used in the fix (standard is 3, but sometimes it could be more);

    it also depends on if they calculate their distance using straight line measurements or follow the path

    When Selective Availability was activated in the GPS system, typical accuracy was around +/- 50 meters. It was a purposeful error built into the system to degrade the accuracy for enemies who might use it for targeting/surveillance. Selective availability was permanently deactivated on May 02, 2000.

    Typical accuracy of modern consumer GPS units is currently around 1 meter, and typical smartphone GPS accuracy has been tested to be around 2-3 meters under ideal multipath conditions, up to 10 meters (or worse) under poor multipath conditions (due to phones having inferior antennae to dedicated GPS units). Nowhere near 0.5 mile.

    http://gpsworld.com/accuracy-in-the-palm-of-your-hand/

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