The E12 light bulb is a candelabra light bulb with a 12-millimeter screw-thread base. These small bulbs generally are found in chandeliers or night lights.
Light bulbs are described by a number to indicate the wattage, a letter to indicate the bulb or glass shape and a number that indicates the diameter of the base, expressed in the number of eighths. In the United States, the base of a light bulb is expressed as the word “medium” and is an indication of about 1 inch in diameter. The synonyms used for medium bases include: E26, “Edison” and “standard.” Screw-thread bases that have been prefixed with the letter “E” followed by a number indicate the diameter in millimeters.