How many C9 bulbs, clips and feet of socket wire do you need for a roofline? Enter the feet and pick your products. The calculator works out your material list, what it costs at wholesale, your cost per foot and what the job can bring in. Each line links to the product so you can order it.
Prices are Grants Outdoor’s listed wholesale prices as of October 2026 and can change. Check the store for current pricing. Bulbs, wire and clips are sold in contractor quantities, so one case usually covers several jobs. The calculator adds 5% extra bulbs, 10% extra wire for cuts and jumps, and 10% extra clips.
How the math works
Sockets = roofline inches ÷ spacing. Every socket needs one bulb and one clip. Add extra for cuts, jumps and breakage.
| Spacing | Bulbs per 100 ft | Bulbs per 1,000 ft spool |
|---|---|---|
| 12 inch | 100 | 1,000 |
| 15 inch | 80 | 800 |
| 18 inch | about 67 | about 667 |
| 24 inch | 50 | 500 |
- 15 inch spacing is the most common for homes: bright from the street without overspending on bulbs.
- 12 inch spacing looks fuller and brighter and is popular on high-end homes and close-up areas.
- Wider spacing (18 to 24 inch) stretches a budget on long commercial runs viewed from far away.
Power check: how many C9 LED bulbs per run?
At 0.85 watts per LED C9 bulb, 100 bulbs draw about 85 watts, or roughly 0.7 amps. Socket wire rated at 7 amps can carry more than you’ll usually put on one run, but you still need to stay within the wire, connector and circuit ratings.
- Plan runs so each one stays well under the wire and connector rating. Many installers keep loads at or below 80% of the rating.
- Use GFCI-protected outdoor outlets and outdoor-rated connections.
- Seal cut ends with clear end caps to keep water out.
- Always follow the manufacturer’s ratings and local electrical code.
You’ll also need
Measure from a photo instead of a ladder
Grants Pro Estimator measures rooflines from a photo, builds the mockup and writes the quote. ChristmasPlug installers get 50% off with code ChristmasPlug.
See Grants Pro EstimatorList my business freeWatch: designing and quoting from your phone
Watch on Instagram
🎥 More install tips and how-to videos: TikTok · Instagram · Facebook
FAQ
How many C9 bulbs do I need per foot?
At 15 inch spacing you need 80 bulbs per 100 feet of roofline. At 12 inch spacing you need 100 bulbs per 100 feet. Add about 5% extra for spares.
How much socket wire do I need?
About the length of your roofline plus 10% for cuts, jumps and corners. Socket wire is sold on 1,000 foot spools.
How many Christmas light clips do I need?
One clip per bulb plus about 10% extra. 100 feet at 15 inch spacing is 80 bulbs, so about 88 clips.
How much do C9 materials cost per foot?
At listed wholesale prices, C9 bulbs, socket wire and clips for a roofline typically come to roughly $1 to $1.50 per foot depending on spacing and brand. Use the calculator for your exact numbers.
Keep reading: Which Christmas light clip to use · C9 socket wire buying guide · Choosing C9 bulb colors · How many mini lights to wrap a tree