So I have been training for last couple of months for a 5K. Never really been much into running, but I am trying to lose weight. I have been using the Couch to 5K app, and running on a treadmill at my gym. I wanted to complete the training on the treadmill first and then move to the road, so this was my last week of training. I had been noticing the treadmill distance saying 2.9 miles when I was done. I have been wearing my series 2 Apple Watch and iPhone while I run. My watch tells me I have done 3.93 miles total and my iPhone says 3.9. My question being which is more accurate? I have never had an issue trusting my iPhone or Apple Watch, but now I am questioning it. Just a few added details. I am running on a speed of 4.7 on the treadmill with a 5 minute warmup walk, 30 minute jog, and 5 minute.