Identifying Light Bulbs

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HARRINGTON LIGHTS is pleased to provide the following information to help in



Light bulbs are generally described by:

  • a NUMBER indicating WATTAGE
  • a LETTER indicating bulb (glass) SHAPE
  • a NUMBER indicating diameter, expressed in the number of eighths of an inch (whether it is an improper fraction or not)
  • an indicator of the finish, whether clear, frost, or in some cases an indicator of flood, spot
  • an indicator of the base of the bulb
  • an indicator of voltage

EXAMPLE (using the corresponding colors above):


The example translates to:  60 Watt, A-shape ("regular light bulb" shape), 19/8" in diameter (correctly adjusted to 2-3/8" diameter if you really want to know the actual dimension), Frost finish, Medium base*, 120 Volt.

*Base:  In the US, "medium" indicates a base that is about 1" in diameter.  Synonyms for medium are "standard", "Edison" and E26. It's best to call medium "medium" or "E26" because when other bases are being discussed, the two other synonyms may cause confusion.  Here in the US and elsewhere, there are other screw-thread bases that are prefixed with an "E" followed by a number indicating diameter expressed in millimeters.  "Edison" is medium in the US, but only by general usage and not by any technicality, unless one is inclined to argue (probably unwisely) that E11, E12, etc., is not an acknowledgment of Edison's contribution.


6lampbases.jpg (41997 bytes)
(Click for larger image)
Left to right: E10, E11, E12, E14, E17, E26


  • E10  Miniature Screw Base  10mm diameter  

  • E11**  Mini-Can (Miniature Candelabra), 11mm diameter

  • E12**  Candelabra (US), 12mm diameter, typically found on night light bulbs, chandelier bulbs

  • E14**  European Base (obviously an American term), 14mm, typically found on imported chandeliers and sconces

  • E17  Intermediate Base, 17mm (appears to be about 5/8" diameter) found on industrial bulbs and on some decorative bulbs

  • E26  Medium Base (US), 26mm diameter (about 1")

  • E39  Mogul Base (US), 39mm, (slightly over 1-1/2") found on some incandescent bulbs and on many HID lamps (NOT SHOWN IN PHOTO)

**Also see:  Identifying Screw Bases



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