Hi Guys, Since I started looking at GPX files made with different GPS units, it has become obvious that their quality differs with regard to drift. Judging by a log I captured with iPhone 4 in 2012, I think the iPhone will show the same problem with distance calculation and clean looking track logs. GPS drift (small GPS built into head cam) : http://www.youtube.com/watch?v=B2nHh8s985M Hiking GPS (Garmin 60csx - I think) : http://www.youtube.com/watch?v=EqEAcw2vV0Y You can see the first one is shaky, and all those zig-zag lines on the track log accumulate extra bogus distance if you're counting it. I assume any way that you calculate distance with a track log you have to do it yourself, even if you use map kit, and native code to calc the distance of the individual legs of the trip. Is there an easy way to overcome this? The only way I can think of is CPU hungry, measuring the distance of every track point from it's surrounding track points.