@Manson82 there are many reasons for differences. First of all, the indoor and outdoor running are slightly different when it comes to mechanics. On treadmill there is no air resistance and you are not really going anywhere (although, in relation to the belt you do). Treadmills usually are not 100% accurate as counters are not synchronized with belt (when your foot lands on the belt, the treadmill speed changes but counters continue with whatever pace/speed you have set). Every watch will struggle with pace and distance on treadmill. You may change your stride length to help it but then you'll find that the same pace as outdoor doesn't make effort the same. One of those will feel harder despite of the pace. The metrics Fitbit gives you are probably not quite correct (wrist watch will find quite difficult to get that right). Indoor, just focus on your effort (match it to what you know from your outdoor runs). You may use heart rate as an indicator of that. Pace and distance aren't that relevant (unless you use foot pod or device like RUNN which provide accurate metrics). Separate indoor and outdoor running and don't put equal sign between them.
