Light Bulb Type Size Reference Guide

 

Light bulb size is determined by the maximum diameter expressed in eighths of an inch (1/8"). For example: A19 light bulb is 19-eighths of an inch or 2 3/8" in diameter. Refer to the more popular bulb type sizes indicated on the scale (calibrated in eights).

To determine a particular bulb size, approximately measure the bulb's maximum overall diameter to the nearest eighth of an inch (1/8").