A fixing device includes a fixing rotator and a lateral end heater to heat a lateral end span of the fixing rotator in an axial direction thereof. A thermal conduction aid contacts the fixing rotator. A nip formation pad contacts the thermal conduction aid. A lateral end temperature detector detects a temperature of the fixing rotator in a lateral end detection span in the axial direction of the fixing rotator. The thermal conduction aid contacts the nip formation pad in a first span including the lateral end detection span in the axial direction of the fixing rotator with a first contact area. The thermal conduction aid contacts the nip formation pad in a second span disposed outboard from the first span in the axial direction of the fixing rotator with a second contact area smaller than the first contact area.