The AC loss characteristics of a coated conductor are determined by the combination of its electromagnetic properties, its geometrical structure, the external magnetic field to which it is exposed, and its transport current. Magnetic fields in a solenoid coil and a one-layer cable are shown as examples of the external magnetic field to which a coated conductor is exposed in electrical devices. The field angle (the angle between the magnetic field direction and the wide face of conductor) and the conductor width are focused on to study the AC loss characteristics of single coated conductor. The AC loss of a whole winding is the sum of the AC loss in each turn of the winding and can be predicted from the AC loss characteristics of single turn of coated conductor and the magnetic field distribution in the winding. The perspective for the AC loss reduction of coated conductor is discussed from both conductor design aspect and winding design aspect.