C7 vs C9 Christmas lights: size, spacing and which goes on your roofline
A C9 is the bigger bulb: about 1⅛ inches wide and 2¼ inches long, on a 17 mm E17 base. A C7 is about ⅞ inch wide and 1½ inches long, on a 12 mm E12 base, and neither fits the other's socket. Rooflines usually get C9s because they're made to be seen from a distance; C7s suit things you see up close, like porches, walkways, shrubs and small trees.
Our seasonal service hangs C9s, with the January takedown and storage included in year one. On average, Christmas lights run about $600; smaller homes often cost less, and the free measure gives your exact written quote. The permanent versions are C9 Classic, on clips, and C9 Track, in a color-matched channel.
C7 vs C9 side by side
The C is for the candle or cone shape, and the number is the diameter in eighths of an inch: a C7 is 7/8 inch across and a C9 is 9/8, or 1⅛.
| Detail | C7 | C9 |
|---|---|---|
| Diameter | ⅞ in. | About 1⅛ in. (Wintergreen lists 1.18 in.) |
| Length | About 1½ in. | About 2¼ in. |
| Base | E12 candelabra, 12 mm | E17 intermediate, 17 mm |
| Incandescent watts | 5 or 7 W | 7 or 10 W |
| LED watts (Wintergreen OptiCore) | 0.8 W, 22 lumens | 0.8 W, 25.5 lumens |
| Stringer spacing | 6 or 12 in. | 6, 12 or 18 in. |
| Most common spacing | 12 in. | 12 in. on rooflines |
| Where it's used | Porches, walkways, outdoor trees and bushes, mantels, indoor trees | Rooflines, fences and posts, pillars, large outdoor trees, commercial displays |
Sizes vary a little by maker. Lengths, bases and uses from 1000Bulbs; diameters and watts from Wintergreen's bulb specifications; spacing from Christmas Lights, Etc.
- C7
- ⅞ in. wide, about 1½ in. long
- E12 candelabra base, 12 mm
- C9
- About 1⅛ in. wide, 2¼ in. long
- E17 intermediate base, 17 mm
Which goes where on a house
Rooflines and gables: C9. 1000Bulbs calls C9s the usual bulb for lining roofs because they can be seen from a distance. That's how a roofline is seen: the whole outline, from the sidewalk or across the street.
Porches, railings, walkways and shrubs: C7. These are seen from a few feet away, where the smaller bulb fits the scale. 1000Bulbs lists C7s for porches, walkways, bushes and trees.
Both on one house. You can mix them: C9s on the roofline, C7s on the porch rail or a front shrub. Just buy bulbs to match each stringer, since the bases differ.
House size, not bulb size, drives the bill. Our planning examples are about 150 feet of roofline for a single-story ranch, 220 for a two-story with gables and 320 for a large two-story lit on all sides. Our seasonal service hangs C9s on the roofline; trees, wreath outlets and railings are quoted at the measure.
Sources[1]
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Checking availability.
Spacing: how far apart the bulbs go
At Christmas Lights, Etc, C9 stringers come with sockets 6, 12 or 18 inches apart, and the store calls 12 inches the most common choice for C9 rooflines; 6 inches gives a dense line for trees and close-up displays. Its C7 stringers come in 6 and 12 inches, with 12 the usual residential choice.
Spacing sets the bulb count. On a 150-foot roofline, 12-inch spacing is 150 bulbs, 15-inch is 120 and 6-inch is 300. Our permanent C9 packages, C9 Classic and C9 Track, use 15-inch spacing.
- 6 in. apart · 300 bulbs
- 12 in. apart · 150 bulbs · the most common
- 15 in. apart · 120 bulbs · our permanent C9s
- 18 in. apart · 100 bulbs
At the free measure we show you exactly where the lights will go on your house before you decide.
Faceted or smooth, LED or incandescent
LED C9 lenses come two ways. Wintergreen's faceted lens has a diamond-cut pattern that throws a halo of light; its smooth, opaque lens gives the traditional look of classic Christmas bulbs. The bulbs in our seasonal service are faceted.
LED or incandescent matters more to your power bill than C7 or C9. An incandescent C9 draws 7 to 10 watts; Wintergreen's LED C9 draws 0.8. Our guide to LED vs incandescent Christmas lights works out what a whole roofline costs to run on Clark Public Utilities and PGE.
Colors
C7s and C9s both come in a wide range of colors, in LED and incandescent. The colors we stock for seasonal installs: warm white, pure white, red, green, blue, multicolor, red and white, red and green. See how each color looks on a house before you pick.
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Seasonal C9s or permanent C9s: how they compare
Same bulb shape, three ways to have it:
| Detail | Seasonal C9 | C9 Classic, permanent on clips | C9 Track, permanent in a channel |
|---|---|---|---|
| What it is | LED C9s in the color you pick, installed, taken down in January and stored | Full-color Minleon C9 bulbs at 15-inch spacing on clips | The same bulb in a color-matched channel |
| How it's priced | By the foot; later seasons are a re-hang of the same layout | By the foot, plus a system line | By the foot, controller included |
C9 Classic's controller is a separate system line on the quote; C9 Track has the controller included.
On average, permanent lights run about $3,000 and Christmas lights about $600; smaller homes often cost less, and the free measure gives your exact written quote. We charge by the foot: simple, honest, no hidden fees. Your written quote spells out everything before any work starts.
The trade-offs: permanent C9s change color from an app all year, while seasonal bulbs stay the color you picked and come down in January. C9 Classic leaves the green wire on the roofline all year, which some HOAs restrict outside the holiday window; C9 Track hides the wire in a channel matched to your fascia. Permanent vs seasonal lights compares the two side by side.
Want C9s that stay up all year?
- C9 Track: Classic C9 bulbs in a color-matched channel. Permanent, wire hidden, looks like Christmas lights should.
- C9 Classic: Full-color C9 bulbs on clips, the way Christmas lights have always been hung. Our lowest-cost permanent option.
Priced by the foot · No hidden fees
Read next
- LED vs Incandescent Christmas Lights: Cost to Run and Look
- How to Hang Christmas Lights on Your House Like a Pro
- Christmas Light Installation Cost 2026: Vancouver & Portland
- Permanent vs Seasonal Christmas Lights: Cost Over Time
- Christmas light installation: what's included and what it costs
Christmas light installation near you: Ridgefield, Salmon Creek, Washougal, Lake Oswego, Happy Valley, Tigard.
C7 and C9 questions
Which is bigger, a C7 or a C9 bulb?
Can I put C9 bulbs in C7 sockets?
Should I use C7 or C9 lights on my roofline?
What spacing should C9 lights be on a roofline?
How many C9 bulbs do I need?
Do C7 and C9 bulbs cost the same to run?
Sources
The outside figures on this page come from these pages, read on September 26, 2026. Makers change specs and stores change prices, so check before you buy.
- 1000Bulbs: C7 vs. C9 Christmas lights · May 9, 2025
- Wintergreen Lighting: C7 warm white OptiCore LED bulbs · 0.8 W, 22 lumens, 7/8 in., E12 base
- Wintergreen Lighting: C9 warm white OptiCore LED bulbs, faceted · 0.8 W, 3000 K, 25.5 lumens, 60,000 average hours
- Wintergreen Lighting: C7 clear transparent incandescent bulbs, 5 and 7 watt · 3,000 average hours
- Wintergreen Lighting: C9 clear transparent incandescent bulbs, 7 and 10 watt · 1.18 in., E17 base, 3,000 average hours
- Christmas Lights, Etc: C7 light strings and spools, spacing guide
- Christmas Lights, Etc: C9 light strings and spools, spacing guide
- Wintergreen Lighting: C9 opaque (smooth) warm white OptiCore LED bulbs