What Bulb For
Your answer

C7 vs C9 vs mini lights: which replacement bulb fits?

The number is the bulb’s width in eighths of an inch: a C7 is 7/8 inch across and a C9 is 1-1/8 inch. Novelty Lights, a holiday bulb maker, gives the C7 the small E12 candelabra base and the C9 the larger E17 intermediate base, and Holiday Living’s clear C9 set takes E17 bulbs.

How does the old bulb come out?

It unscrewsA screw-in bulb, such as a C7 or C9It pulls straight outA tiny bulb, or an LED under a coverNot sureTell the base apart by its look

What’s in the socket?

A tiny glass bulbA mini lightAn LED under a shaped coverThe cover looks like a C7 or C9 bulb
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How wide is the bulb at its widest point?

Or read the code on the box or the set’s tag.

About 7/8 inchMarked C7About 1-1/8 inchMarked C9
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What fits

A mini bulb with your set’s volts and watts

Mini bulbs differ from set to set. GE’s mini sets take 2.5 volt bulbs, at 0.25 or 0.425 watts depending on the set.

Available on Amazon

Mini replacement bulbs
  • Push the new bulb straight in. On GE’s sets, a twisted bulb can leave part of the set dark.
  • GE marks its fuse bulbs with a white ring. Replace one only with a spare fuse bulb from the set.

See also

Christmas light fuses
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What fits

Use the set’s own spare LEDs

On GE’s LED C9 set, the C9 shape is a cover over a push-in LED.

  • On that set, the cover comes off with a counterclockwise turn.
  • After changing the LED, turn the cover clockwise so it fits tightly.

See also

Christmas light fuses
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What fits

C7 bulbs, E12 candelabra base

7/8 inch across.

On the package: C7, E12 (candelabra)

Available on Amazon

C7 replacement bulbs (E12) C7 LED replacement bulbs
  • Take the old bulb or its box along to compare the base.

See also

Christmas light fusesLight bulb base types
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What fits

C9 bulbs, E17 intermediate base

1-1/8 inch across. Holiday Living’s clear C9 set takes E17 intermediate-base bulbs.

On the package: C9, E17 (intermediate)

Available on Amazon

C9 replacement bulbs (E17) C9 LED replacement bulbs
  • Match the old bulb’s watts, within the most per bulb that the set’s instructions allow.

See also

Christmas light fusesLight bulb base types
Start over

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Unplug the set before you change a bulb, and let the old bulb cool.

Mini light bulbs push in rather than screw in. Match the volts and watts printed for your set.

C7 or C9

C7 and C9 follow the same rule as other bulb codes, such as A19. Satco’s 7 watt clear C7 (S3691), for example, is 0.88 inch across at its widest, about 7/8 inch, and has an E12 candelabra base.

Night light bulbs can be C7s too: Feit’s 4 watt C7 night light bulb has an E12 candelabra base.

Watts per bulb

Don’t fit a bulb with more watts than the set allows in each socket. Holiday Living’s clear C9 set, for example, takes bulbs of 7 watts at most.

Two kinds of set

The federal rule for holiday lights describes two kinds: sets with push-in or miniature screw sockets wired in series, as on GE’s mini sets, and sets with candelabra or intermediate screw sockets wired in parallel, directly across the 120 volt supply.

Common questions

What does the C in C7 stand for?

It's the shape letter. Bulb makers group C with B and CA as candle shapes.

Keep going

Christmas light fusesHow many light stringsHalf a string outBulb codesLight bulb base types

Where we get our information from

The widths come from the bulb makers’ size guides, the bases and bulb ratings from Feit’s product page, the light set makers’ own instruction sheets and a holiday bulb maker’s help pages, and the two kinds of set from the federal rule on holiday lights. Checked against published data from GE, Feit Electric, GE Lighting, Signify and Westinghouse (plus 4 more).

See all 12 sources
  • GE Lighting, “A Guide to Light Bulb Sizes, Types, Shapes, and Codes” (2022)
  • Feit Electric, “Decoding Bulb Shapes and Sizes” (2017)
  • Philips Lighting (Signify), Lamp Specification Guide 2015: shape codes, color rendering, color names, safety notes
  • Westinghouse Lighting, “Bulb Size” guide, and lamp catalog: shape sizes in eighths of an inch
  • GE mini light set instructions, models 61515LO and 61516LO (Nicolas Holiday, 2025): set watts, end-to-end maximum, amps times 120, fuses, GFCI outlet outdoors
  • Holiday Living light set instructions: clear C9 set W11C0154 (432 W maximum) and 6.5 ft. pre-lit Seneca Pine tree W14L0441 (lights rated 24 W, 216 W maximum)
  • 16 CFR 1120.2(d) and 1120.3(c): seasonal and decorative lighting products, and the UL 588 wire size, strain relief and overcurrent protection (fuse) requirements
  • Feit Electric, 4W C7 E12 candelabra base night light bulb (BP4C7/W/4/RP) product page
  • GE LED C9 Color Choice set instructions, models 89120LO and 89420LO (Nicolas Holiday, 2024): push-in LED lamps under C9 covers, spares only
  • GE 50, 100 and 150 light mini sets with fuse bulbs, instructions IM-56 (Nicolas Holiday, 2021): fuse bulbs, bulb ratings, 50-bulb circuits
  • Novelty Lights knowledge base (a holiday bulb maker and seller's help pages): C7 and C9 base sizes
  • Satco, S3691 7 W C7 incandescent product specs (satco.com; read by the owner in a browser, October 18, 2026): E12 candelabra base, MOD 0.88 in., MOL 2.13 in.

General guidance from manufacturer and standards data. Products vary, so check the label and the maker's instructions.