Are C7 and C9 bulbs the same?

by | Oct 27, 2022

Great question, and we hear it several times a season.

Short Answer: No, they are very similar but are different sizes.

Longer Answer: C7 bulbs are shorter with smaller diameters than C9s. Both are installed in 18 AWG traditional Christmas light cords. Many of us remember this style of lighting from when we were kids.

Many Christmas displays use both sizes of bulbs but each bulb has its own type of cord.

Here is a photo of glass C7 and C9 bulbs showing their relative size difference.

Are C7 and C9 bulbs the same?

Questions about what size bulb/cord you have in your stash?

A C7 bulb has the same sized socket as a nightlight so using a nightlight bulb for reference can help in determining the size of an unmarked cord.


Are C7 and C9 bulbs the same?
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