Gps tracking running app discrepencies.

[funkpod]

Hey, I'm training for a marathon so I am using SportyPal Pro and Cardio Trainer a lot
Usually they ate pretty accurate, but on a longer run, the discrepencies are more pronounced. For instance, I went for a 14 mile run today and Sporty pal told me that I went 14 miles while cardio trainer said I went 15... That's a big difference.

Looking at walkjogrun.net I probably did more like 15, but why was sporty pal so off?

Or was cardio trainer off? I've read issues about cardio's reliability but not about sport pal's. ..

 

[Ravenbrook]

I've noticed that Google Maps is spot on, but when I use apps like The Weather Channel it can be anywhere from 200-300 yards off up to 2-3 miles off! Not sure what's going on...