I finished my running session on a officially measured OUTDOOR running track (5,3km). I ran 1 lap plus a little to the bus station (cca. 800m back and forth), and the app counted 8.1km. Very inaccurate and also disappointing. I also checked the gps-tracked route, and I noticed that the line is like a sawtooth on perfectly straight route. I repeat it was outdoor. I think you should work more on the accuracy or gps reliability of the app, because if my previous 30$ mi band 3 was able to do that, I think it's not an impossible task.