Indoor track running app

An app for indoor tracks that allow me to set a fixed distance per lap. 

The current Garmin app uses stride lengths (I think) to determine a distance.  The Garmin result is usually very different from the actual distance ran.  For example, my track is 9 laps per mile (in the center lane).  I did 30 laps (3.33 miles).  Garmin said I ran 3.01.  Not a huge split, but it only gets worse the further I go.