To measure your roofline for Christmas lights, measure the straight gutter runs from the ground with a tape, then add the sloped edges of every gable and peak you want lit. The gutter is easy because it runs right above a line you can walk. Gables take a little math, since the slope is always longer than the width. You can do the whole thing in 15 minutes without a ladder, and a satellite map view makes a good double-check.
Here are three ways to do it, from most accurate to quickest. Pick one, or use two and compare.
First, decide what you’re lighting
Before you measure anything, grab your phone and take a photo of the front of the house from the street. Then decide which lines you want lit:
- The gutter line only. The flat, horizontal edge along the front. Simplest look.
- Gutter plus gables. Adds the sloped “A” shapes over the garage, porch, or front rooms.
- Everything. Gutters, gables, dormers, and the ridge line along the top.
More lines means more footage. Drawing the lines right on your photo with a markup tool is the easiest way to keep track.
Method 1: tape measure and a helper (most accurate)
This is the one to use if you’re buying lights for a DIY install.
What you need
- A 25-foot or longer tape measure (a 100-foot reel tape is even better)
- A helper
- Your phone for notes
- Your marked-up photo
Straight runs
Stand under the gutter and walk the tape along the ground right below it, corner to corner. The gutter sits directly above that line, so the ground distance is the gutter distance. Write each section down separately: “garage, 24 feet,” “front porch, 18 feet,” and so on. Separate numbers help later, because every section usually needs its own connection.
Gables and peaks
This is where people come up short. The sloped sides of a gable are longer than the width of the gable, and how much longer depends on how steep the roof is.
Measure the gable’s width at its base from the ground. Then:
- Low pitch (a gentle slope, common on ranches): the two sloped sides together come to a little more than the width.
- Moderate pitch (a typical two-story house): the two sides together come to roughly 1.2 times the width.
- Steep pitch (tall, pointy gables): the two sides can come to 1.4 times the width or more.
So a 20-foot-wide gable with a moderate pitch needs about 24 feet of light to outline both sides. When in doubt, round up. Coming up two feet short on a gable is far more annoying than having a little extra.
Don’t forget
- The run from the outlet to the roof. Measure from your outdoor outlet to where the lights start. That’s cord, not bulbs, but you still need it.
- Corners and returns. If the gutter wraps around a corner and you want it lit, include that side.
- Gaps you want to skip. Subtract any sections you plan to leave dark.
Method 2: satellite map view (good from the couch)
Most free online map tools have a satellite view and a “measure distance” feature. Search your address, switch to satellite, and click along the edge of your roof.
Tips for getting a useful number:
- Trace the gutter edge, not the middle of the roof. Follow the outer line of shingles.
- Measure each side separately and write it down.
- Watch out for gables. A satellite image looks straight down, so a gable’s slope shows up as a flat line. The map gives you the width, not the sloped length. Use the pitch multipliers from Method 1 to adjust.
- Trees hide things. If an oak covers half the front, the tape measure is more reliable there.
This method is great for a quick estimate, and it’s a nice sanity check against your tape numbers. If the two are more than about 10 feet apart, measure the tricky section again.
Method 3: count gables and siding (the fast estimate)
No tape, no map. Just stand in the driveway and count.
- Count the gables on the front of the house.
- Estimate the front width. Pace it off (a normal adult step is roughly two and a half feet) or count siding boards if you know their width.
- Add them up. Front width, plus the sloped length of each gable using the multipliers above.
Example: a ranch with a 60-foot front and one 24-foot gable over the garage with a low pitch.
- Gutter line: 60 feet
- Gable sides: about 26 feet
- Outlet to roof: about 10 feet of cord (separate from the bulb run)
- Total bulb run: about 86 feet, so plan on around 90 feet of strand and about 90 bulbs at one per foot
It won’t be exact, but it gets you within a strand or two.
Turn footage into bulbs and clips
Roofline C9 and C7 bulbs are usually spaced 12 inches apart. That keeps the math friendly:
- Bulbs: about one per foot
- Clips: about one per bulb on a roofline
- Strands: your total footage, broken into the sections you measured
If you’re curious what those bulbs will add to your power bill, our electricity guide runs the numbers for a 100-foot roofline.
Measuring worksheet
Copy this into your phone notes and fill it in:
- Front gutter runs (each section): ____ ft
- Side returns you want lit: ____ ft
- Gable 1 width ____ ft × pitch multiplier = ____ ft
- Gable 2 width ____ ft × pitch multiplier = ____ ft
- Dormers or porch roof: ____ ft
- Ridge line (optional): ____ ft
- Outlet to first bulb (cord): ____ ft
- Total bulb run: ____ ft
Or skip the tape
If you’d rather not measure at all, you don’t have to. Text one photo of the front of the house and the address to (470) 470-4485 and we’ll work out the footage for your free written quote. We cut commercial-grade LED strands to the measured runs, so each strand ends where your roofline ends. Clips hold everything without nails or staples, and a timer is set before we leave.
Start with roofline lights, add trees and shrubs, or go with the whole-house package. In January we handle takedown and storage, so the strands you measured this year are ready for next year. If you manage a neighborhood entrance, the HOA and entrances page covers signs and landscape beds.
We work across the metro, including Marietta, Roswell, Alpharetta, Lawrenceville, Smyrna, and Peachtree City. Prefer a form? Use the contact page.
Common questions
How do I measure my roofline for Christmas lights?
Measure the straight gutter runs along the ground with a tape, since the gutter sits right above them. Add the sloped edges of each gable, which are longer than their width. You can check the total with a satellite map’s distance tool.
How do I measure a gable without getting on the roof?
Measure the width of the gable at its base from the ground. For a common moderate pitch, each sloped side is a bit more than half that width, so the two sides together come to a little more than the full width. Steeper roofs run longer, so round up.
How many C9 bulbs do I need per foot of roofline?
Roofline C9 and C7 bulbs are usually spaced 12 inches apart, so plan on about one bulb per foot. A 90-foot roofline takes about 90 bulbs and about 90 clips.
Do I need to measure before I ask for a quote?
No. A photo of the front of the house and the address is enough for us to start. Measuring is handy if you plan to hang lights yourself or want to understand what your quote is based on.
