Light Bulb & Socket Guide hopes to take the guessing game out of string light and bulb shopping. There are only three bulb sizes that we sell: C7, C9 and Medium. These are the names we use, but these bulb sizes can go by many different names. The images below provide a great visual for bulb size comparison.

A Bulb By Any Other Name...

  • C7 Bulbs have a candelabra or E12 base. This size bulb is typically used for chandelier-type fixtures and decorative lighting.
  • C9 Bulbs have an intermediate or E17 base. These are historically known as the old Christmas light bulb size.
  • Medium Bulbs have a E26 base (E27 in Europe). This is the same size as a standard household bulb.

Bulb Naming Convention

Besides the C7 or intermediate size references, the base size has the letter-number format. The first letter designates the shape or form of the base. The number represents the width of the base (normally in millimeters). For example, our 11S14 bulb has an E26 base. The "E" refers to the style which is an Edison screw-in, and the 26 means it has a 26 mm base width.

Socket Comparison

The following image provides dimensions of a bulb socket so if you're trying to match the socket size of a bulb you already have, this provides a comparison so you know the socket size of your bulb.

Bulb Socket Comparison

Bulb Comparison

The image below compares our three C7 (E12) base bulb sizes: G30, G40 and G50.

Bulb Comparison - G30, G40, G50 Globe Sizes

The image below compares our G40 and G50 bulbs in C7 and C9 base sizes.

Bulb Comparison - G40 & G50 in C7 and C9 Socket Sizes

The image below compares our G50 bulbs in all three base sizes.

Bulb Comparison - G50 in three socket sizes

Bulb Shopping

All three bulb socket sizes are available at — C7/E12/Candelabra base, C9/E17/Intermediate base and Medium/E26 base.