You don't need to be an 'investor' to invest in Singletrack: 6 days left: 95% of target - Find out more
I have been stepping up my running over the summer and, now that I am doing longer distances, I am noticing how inaccurate it can be and just checking to see if this is normal. I use a Fitbit Blaze connected to my iPhone to track my runs. Last Sunday I did a run which tracked at 10.09 miles. I did the identical run a couple of days ago and it tracked at just 9.92 (so 0.17 miles) shorter. I could accept perhaps a .02 / .03 discrepancy but this is a huge difference. I checked the maps and they both show the same route without any apparent drop-outs in coverage so I don't know where the difference came from.
I know it isn't the end of the world, but it's annoying nonetheless. Does anyone else find they get similar inaccuracies?
Not surprising, the iPhone GPS is notoriously inaccurate. You'd be better off using something like a Garmin, Wahoo or Polar to get accurate mapping. It's all to do with how often the GPS tracks you - have you got 1 second tracking or smart?
Hmm no idea - what is the difference?
Mrs had a fitbit connected to her phone for running, IME they're fine as a lifestyle tracker, but not a good setup for GPS.
Bought her a garmin instead.
the iPhone GPS is notoriously inaccurate
10 yrs ago maybe. now they all use the same chips.
and he's using a fitbit which has built in GPS so I'm not sure you can blame the iphone...
assuming it is a 10mile run, +-1% error between them seems ok to me for a consumer grade GPS with a accuracy of +-10m.
you might have to wait for the Fitbit RTK if you want better..
assuming it is a 10mile run, +-1% error between them seems ok to me for a consumer grade GPS with a accuracy of +-10m.
This
Fitbit blaze does not have GPS Jam bo, uses your phone.
Used the distance correction option on the run's headline page?
I've got a Fitbit Versa and have noticed it is way out compared to my Garmin. I've used both together on runs and found the Fitbit was always short, however the Garmin more or less matched friend's results who were using a variety of devices. I recently used it during a proper 10k run and the distance came up over 1 mile short - quite a lot over just 6 miles!!
I've given up using it when riding as it just couldn't cope and would just join up a series of points with straight lines and not show the route correctly at all. Either that or it would just auto pause for no reason.
Shame as I love it for everything else it does, but have given up using it to record runs and rides.
and he’s using a fitbit which has built in GP
No it doesn't- it's a Blaze so it relies on the phone GPS (I link the Blaze with the iOS App for Fitbit which then, in turn, shares data with my Strava account).
Used the distance correction option on the run’s headline page?
Tell me more...
EDIT - I did that to both runs and it's closer but still an .08 mile difference). LOL
jam bo Subscriber
10 yrs ago maybe. now they all use the same chips.
Is the GPS chip itself the sole thing that determines accuracy, or does some of this come down to how it is mounted in the unit itself and how the device handles/analyses the data coming from it?
I imagine there is some interpretation of the data coming from the GPS chip by the device.
and he’s using a fitbit which has built in GPS so I’m not sure you can blame the iphone…
I don't think the Blaze has built-in GPS. I think it needs a phone to get the GPS data.
assuming it is a 10mile run, +-1% error between them seems ok to me for a consumer grade GPS with a accuracy of +-10m.
Yep. We're only talking about a ~1% error here.
When my Garmin Edge500 used to consistently read 10% out compared to a mates Garmin, that was quite annoying. Fixed with a firmware update, (although being Garmin that firmware update cocked up other stuff....)
True - I guess I am being a bit over-optimistic about how accurate it should be. Now I have corrected the distances it looks like I will need to start running more quickly though to keep to my target pace 🙁
Is the GPS chip itself the sole thing that determines accuracy, or does some of this come down to how it is mounted in the unit itself and how the device handles/analyses the data coming from it?
I imagine there is some interpretation of the data coming from the GPS chip by the device.
There's a lot of smoothing and checking going on, my cheap chinese phone is much less 'accurate' than the old samsung s4 it replaced, I figure it just takes the raw data from the gps and assumes it's correct, whereas a phone with accelerometers, compasses etc can figure out it's speed and direction and get a position via dead reckoning which it can compare to the GPS.
Alternatively you may have just zig-zagged more or less! 250m difference is possibly just a few road crossings and going via the postbox to drop something off. Or just pressing start before you actually left the house and failing to stop immediately when you get back.