Light Bulb & Socket Guide
Light Bulb & Socket Guide
Learn the most common bulb base sizes and how to match them to your sockets.
If you're building your own string light setup, it's important to know which light bulbs will fit your sockets. Without the right match, the bulbs simply won't screw in! This guide explains it all.
Bulb & Socket Quick Reference
- Bulb & Socket Base Sizes
- Bulb Shapes
- Globe Size Comparison
Light Bulb Base Sizes
PartyLights carries three of the most common base sizes used in decorative string lights. The industry uses many terms for the same size, so we've tried to use them collectively to avoid confusion.
✔ Three most common light bulb base sizes
✔ How to choose the right socket
✔ Match the bulb and cord socket sizes
C7 / E12 / Candelabra
WIDTH: 0.47 in. / 12 mm
The smallest of the three. Used in decorative fixtures, chandeliers, and small night lights.
C9 / E17 / Intermediate
WIDTH: 0.668 in. / 17 mm
Less common in everyday use. Found in some appliance bulbs, small desk lamps, and accent fixtures.
Medium / E26
WIDTH: 1.03 in. / 26 mm
The most common in North America. This is the standard household socket found in lamps and ceiling fixtures. (In Europe, the equivalent is the E27.)
Light Bulb Shapes
Similar to identifying a base size, light bulbs use a letter-number reference to reflect the shape and size of a light bulb. The letter refers to the shape, and the number refers to the size*. Here's a list of the letters used for bulbs we carry and their meaning:
- A (Arbitrary) ... Most closely resembles a standard household bulb.
- C (Conic) ... Often referred to as like a traditional Christmas tree bulb.
- G (Globe) ... Round or circular shape.
- S (Sign) ... Sometimes called straight-sided, they were traditionally used in signs.
- ST (Straight Tapered) ... This shape is most often seen in vintage, Edison-style bulbs.
- T (Tubular) ... A tall narrow tube-shape often used in vintage, Edison-style bulbs.
Below shows the bulb styles available at PartyLights.com for our decorative string lights:
G30 / G40 / G50
Compares three popular bulb shapes to compare globe sizes.
All shown in the C7/E12/candelabra base size to show that it's just the globe part that gets bigger.
G40 vs G50 and E12 vs E17
Compares the G40 and G50 globe sizes in two different socket sizes.
It shows that the globe size doesn't change even if the socket size does.
G50 in three socket sizes
Compares the G50 bulbs in all three socket sizes.
Once again, it shows that the globe size doesn't change even though the socket size gets bigger.