An air compressor includes a compressor assembly with a motor and a pump driven by the motor, a battery receptacle, and a battery pack electrically connected to the motor via the battery receptacle for providing electrical power to the motor. The battery receptacle and the battery pack are positioned adjacent the compressor assembly. The compressor also includes a storage tank that receives compressed air from the pump, a case enshrouding the compressor assembly, an outlet port in fluid communication with the storage tank, and an adjustable pressure regulator at least partially positioned within the case. The outlet port configured to discharge compressed air from the storage tank at a regulated pressure determined by the pressure regulator. The compressor further includes an adjustment knob to adjust the regulated pressure of compressed air provided by the outlet port. The case attenuates noise emitted by the compressor assembly to less than 68 decibels.