Standard Light Bulb Base Sizes

Screw bases come in several sizes and they are referred to by both a descriptive name and size.

Standard light bulb base sizes.

Medium standard base code. The most commonly used a series light bulb type is an a19 bulb or its metric iec equivalent the a60 bulb which is 19 8 in 2 3 8 in. Unlike the light bulb shapes the number in the light bulb base measures the light bulb base diameter in millimeters. 60 mm wide at its widest point and approximately 4 3 8 inches 110 mm in length.

This base was developed by thomas edison for the first light bulbs and is still in use today. They are commonly used for general lighting in standard light fixtures such as ceiling lights lamps can lights outdoor spotlight and flood light fixtures and vanity lights. E26 is the size of most light bulbs used in the u s. Standard arbitrary a bulbs are the most widely used and thought of when it comes to household lighting.

The candelabra e12 has a diameter of 12 millimeters. Look at your fixture to determine its base type. The first letter designates the shape or form of the base and the number represents the width of the base normally in millimeters. Fluorescent pin bases miniature bipin medium bipin single pin recessed double contact 4 pin single ended 4 pin 2gx 13 axial twist lock bases 10mm gu10 10mm gx10 24mm gu24 bi pin bases 4mm g4 4mm gu4 4mm gz4 5 3mm g5 3 5mm g5 5 3mm gu5 3 5 3mm gx5 3 5 3mm gy5 3 6 35mm g6 35 6 35mm gy6 35 6 35mm gz6 35 8mm gy8 8 5mm g8 5 9mm g9 9mm g9 pin.

It s used for nightlight bulbs and sometimes for decorative light bulbs used in chandeliers and over bathroom mirrors. Screw in bulbs use a base called an edison screw or es base. Other sizes with a data sheet in iec 60064 are a50 a55 a67 a68 a71 a75 and a80. From top left to bottom right.

E17 intermediate base is in between these two sizes. Common bulbs with e26 e27 bases. Bulbs with these base types are available in many different styles. It s referred to as having a medium or standard base.

A further explanation of the light bulb base sizes you can look at the letter number references e12 e17 and e26 to help understand a bulbs base style and size. Most common light bulb uses including lamps recessed flush mount flood lights are going to have one of the first three base types shown above. Shoppers of led light bulbs often confuse the specifications for base type e26 or e27 and bulb shape a19. Look at your fixture to determine its base type.

Pin type bases are normally used for track lighting landscape bulbs.