• Magazine, a periodical publication.
• Magazine (disambiguation), for other uses such as firearm component.
• Magnum, stemming from the Latin word for large
• Magnet
• Magnification, in optical devices
• Magneto, an engine component (typically in the context of aviation)
• Magnesium alloy wheels, commonly called 'mags'
• Magnetometer a type of instrument frequently part of spacecraft science missions.

MAG may also be an acronym meaning:

• Manchester Airports Group, the largest UK-owned airport group, operating Manchester Airport and three others
• Maricopa Association of Governments, a regional council of governments representing the Phoenix metro area, Arizona, USA
• FN MAG machine gun. MAG stands for Mitrailleuse d'Appui General which translates to 'general purpose machine gun'
• a Magnetic Accelerator Gun, such as a Gauss gun, Railgun or Coilgun
• Massive Action Game, a video game currently in development by Zipper Interactive for the PlayStation 3.
• Maximum Absorbency Garment, a diaper-like garment worn by astronauts during lift-off and spacewalks
• Men's artistic gymnastics
• Memorial Art Gallery, an art museum in Rochester, New York
• Mines Advisory Group, a non-governmental organization (NGO) concerned with removal of debris of war (landmines, unexploded ordnance, etc.)
• Myelin-associated glycoprotein

It may also mean:

• MAG (cryptography), a stream cypher
• Madang Airport, which has IATA code MAG
• MAG Technology Co., a company making computer display devices.
• Mog (people) a scheduled tribe in Tripura whose name is sometimes translitereated Mag.
• A helpful, familiar-like companion robot in the game Phantasy Star Online.