I use both my Apple Watch and Fitbit One to count steps. What I've noticed is that my Fitbit is much more accurate than my Apple Watch. I've calibrated my Apple Watch using the workout app on my watch and walking with my iPhone for 20 minutes. In fact, I've held the phone in my left hand (I wear my watch on my left wrist) during my entire outdoor walk. I've done this numerous times. What I've found is that the Fitbit does a much better job of counting steps. Today, I did an experiment where I started wearing my Fitbit at the same time I started wearing my Apple Watch. As the day went on the gap in the step count widened. As of the time of this writing, my Fitbit has 9,994 steps and my Apple Watch is at 7,914. When I look at my Fitbit when walking it counts steps exactly as they happen. I just purchased a SS after owning a SGS for 9 months. The same issue happened on the SGS. Overall, I''m very happy with my AW, but extremely disappointed in its fitness tracking ability. I guess I'll stick with the Fitbit for fitness tracking and use the AW for everything else. I just don't think Apple is doing a very good job with fitness on both the AW and the Health App. Am I doing something wrong here? Am I missing anything?