It should work in a pants pocket. It probably won't work in a shirt pocket. A coat or jacket pocket is iffy. If the coat or jacket is loose-fitting and can move differently than your body, the measurement probably won't be accurate. The closer to your leg, the better. (Stuffing the phone into a secure sock will work if you don't want it in a pocket. Put it into a pair of zipped zip-lock baggies, with the "zippers" on opposite sides, if there's a chance you could step in water.)