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Christmas Light Footage Calculator
Measure the front of the house once. Get linear feet, bulb count, how many strands to pull off the shelf, clip count, amp draw and crew hours — before you quote it.
- Bulbs143
- Strands (25 ft)6
- Clips151
- LED load137 W
- Amp draw1.1 A
- Circuits1
- Crew hours (2 people)3.9
LED wattage assumed. Incandescent C9 pulls roughly 7W a bulb — seven times this load.
How the estimate is built
The single measurement that matters is the width of the house across the front. Everything else is a multiplier. Lighting the front only is roughly that width; adding both sides brings you to about 1.7×; running the full perimeter is roughly 2.4×. Roof shape then adds run: a simple gable adds about 10%, a hip roof 25%, and a complex roof with dormers, returns and multiple peaks close to 45%. Height adds run too, because second and third stories mean more gable faces and more vertical transitions — not just harder access.
Bulb count comes from spacing: C9 and C7 at 12 inches, minis at roughly 4. Clip count matches bulb count with 5% spare. Load is calculated for LED — 0.96W per C9, 0.6W per C7, 0.07W per mini — and circuits are sized so no single 15-amp circuit carries more than 12 amps continuously. Crew hours assume two trained installers at about 55 feet an hour, halved for multi-story access.
Now show them what it'll look like.
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Common questions
How many feet of Christmas lights do I need for my roofline?
Start with the width of the house across the front, then multiply: about 1.7× for front plus both sides, 2.4× for the full perimeter. Add 10-45% depending on roof complexity — a simple gable adds little, a multi-peak roof with dormers and returns adds nearly half again. A 50-foot two-story hip roof lit front and sides typically needs around 160 linear feet.
How many C9 bulbs per foot?
One bulb per foot is the standard commercial spacing for C9 and C7. Twelve-inch spacing reads cleanly from the street and is what nearly every pre-made commercial spool uses. Eight-inch spacing looks denser and richer but raises bulb count by 50% and pushes your amp draw up with it.
How many amps do Christmas lights draw?
LED C9 bulbs pull roughly 0.96W each, so 200 bulbs is about 192W — under 2 amps. Incandescent C9s pull 7W each, so the same 200 bulbs would be 1,400W, nearly 12 amps, and you'd need a dedicated circuit. Never load a 15-amp household circuit past 12 amps continuous.
How long does it take to install a Christmas light roofline?
A trained two-person crew runs about 55 linear feet per hour on a single story. Two stories or higher slows that by roughly half because of ladder repositioning and safety setup. A 160-foot two-story job is typically a 4-5 hour install.
How many clips do I need?
One per bulb, plus about 5% for breakage and the extra clips you'll want at corners, peaks and transitions. Shingle clips, gutter clips and ridge clips are not interchangeable — count each roof surface separately before you order.