Plain House Manual

Tools: do the math

Systems with a free kit

Guides: one question each

Every tool is free and ends with a sheet to print.

Chapter 03Fit · Tool and printable record

How many feet of holiday lights does the house need?

Quick answer

Measure each run you want to light, add 10% for corners and overlaps, and divide by the lit length on the box, rounding up. A window takes its perimeter and a door its two sides and top. For a gable you do not need a ladder: measure the width at the eaves and estimate the rise, and the tool works out the sloped edges. Bushes take one 4 by 6 ft net per 24 sq ft of face, and a tree about 100 lights per foot of height.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

A two-story house at night with white bulbs along the eaves and the gable, lit hedges and small lit trees by the fence
Example189 ft, 10 sets48 ft of eaves, a gable, 4 windows

Holiday light length calculator

Calculator
Roofline, measured from the ground

Straight eaves: stand under each corner of the gutter, mark the ground and tape the marks. Leave the rise at 0 if you are not outlining a peak.

Windows, doors and railings (leave 0 to skip)
Bushes and a tree (optional)

Result 189 ft of lights: 4 roofline sets and 6 smaller sets

Roofline (straight 48 ft, gable 26.8 ft)
82.3 ft with 10% slack · 4 sets of 25 ft · 2 plug points
Windows
70.4 ft with 10% slack · 4 alike, 17.6 ft each · 4 sets of 20 ft · 4 plug points
Doors
18.7 ft with 10% slack · 1 set of 20 ft · 1 plug point
Railings and edges
17.6 ft with 10% slack · 1 set of 20 ft · 1 plug point
Bushes, 12 sq ft of face each
3 nets of 4 by 6 ft (24 sq ft), 1 a bush
Tree, 7 ft tall
700 lights at 100 a foot · 7 sets of 100

8 plug points: each area starts at its own cord, and no run goes past 3 sets end to end, the number you read on the tag.

Measured 171.8 ft; the 10% slack covers corners, overlaps and the turn at each end. The cord from the outlet to the first bulb is not in this count.

How to use this, in plain words

  1. Stand across the street and decide what to light: the eaves, the peaks, which windows, the door, the rail, the bushes.

  2. Measure the eaves on the ground. Stand under each gutter corner, mark the spot with a stone or chalk, and tape from mark to mark.

  3. For each gable, tape its width at the eaves on the ground. Estimate the rise by counting rows of siding and measuring one row at the bottom.

  4. Write down the window and door sizes, the rail length, the bush sizes and the tree height.

  5. Read the box and the tag: the lit length of each set and the most sets end to end. The lit length is shorter than the cord, because the lead to the plug has no bulbs.

  6. Type it all in. Buy the sets the result gives and fill in the printable sheet with which set goes where.

Before you start

  • Note 01

    Measure what you can see from the street

    Neighbors see the front and maybe one side. Measure those runs only, and leave the back of the house off the plan.

  • Note 02

    Buy the same set for each run

    Sets from different boxes can differ in bulb spacing and color. Buy all the sets for one run in one go, from the same product.

  • Note 03

    Plan with the lit length

    The box often gives a lit length and a total length. Use the lit length; the extra lead at the plug end is what reaches the cord.

  • Note 04

    Count the clips too

    Clips hold the set to the gutter or the shingles. Count the bulbs on the box, read the spacing on the clip pack, and buy enough for the whole run.

How it works

  1. Each run: the measured feet plus 10% slack for corners, overlaps and the turn at each end. Windows use the perimeter, 2 × (width + height), plus the same 10%.
  2. A gable's two sloped edges: 2 × √((width ÷ 2)² + rise²). That is the right-angle rule, so you can measure the width on the ground and never climb to the peak.
  3. A door outline is both sides plus the top, 2 × height + width. The sill stays dark.
  4. Sets per run: the run with slack divided by the lit length on the box, rounded up. Each window and each door is its own run, because a set cannot be cut to share.
  5. Plug points: the sets in a run divided by the most sets end to end printed on the tag, rounded up. The tool has no default for that number, because it differs by set.
  6. Bushes: width × height of the face, divided by the 24 sq ft a 4 by 6 ft net covers, rounded up per bush. Tree: about 100 lights per foot of height.

Source: Christmas Light Emporium planning guide, checked October 9, 2026; 1000Bulbs holiday lighting guide, checked October 9, 2026.

Worked example

A two-story house with 48 ft of straight eaves across the front and one gable over the porch, 24 ft wide at the eaves and about 6 ft from the eaves to the peak. Four windows of 3 by 5 ft, a 3 by 7 ft front door, a 16 ft porch rail, three 4 by 3 ft bushes and a 7 ft tree in the front window. The roofline sets are 25 ft C9 strings, the window and rail sets are 20 ft minis, and the tag says to connect no more than 3 sets end to end.

  1. The gable is 24 ft across and rises 6 ft. Each sloped edge runs from the corner to the peak: half the span (12 ft) across and 6 ft up, so √(12² + 6²) = 13.4 ft. Two edges make 26.8 ft.
  2. Roofline: 48 ft of straight eaves + 26.8 ft of gable = 74.8 ft. Add 10%: 82.3 ft. At 25 ft a set that is 4 sets, and at 3 sets a run, 2 plug points.
  3. Each window is 3 by 5 ft, so 2 × (3 + 5) = 16 ft round it, 17.6 ft with slack: one 20 ft set each, 4 for the 4 windows.
  4. The front door gets both sides and the top, not the sill: 2 × 7 + 3 = 17 ft, 18.7 ft with slack, 1 set. The 16 ft porch rail needs 17.6 ft, 1 set.
  5. The 3 bushes, 4 by 3 ft, have 12 sq ft of face each, under one 24 sq ft net: 3 nets. The 7 ft tree takes 7 × 100 = 700 lights, 7 sets of 100.
House front, to scale (6 px a foot) 6 ft rise 12 ft 13.4 ft 13.4 ft 48 ft, gutter end to gutter end, taped on the ground Roofline arithmetic Gable edges 2 × √(12² + 6²) = 26.8 ft Eaves + gable, plus 10% 74.8 ft → 82.3 ft Sets of 25 ft, rounded up 82.3 ÷ 25 → 4 sets Tag says 3 sets end to end 4 sets → 2 plug points
Fig. 1The worked example: 48 ft of eaves taped on the ground and a 24 ft gable with a 6 ft rise, giving 26.8 ft of sloped edge, 82.3 ft with slack, four 25 ft sets and two plug points.

If the answer surprises you

The result is more than the house length

The 10% slack and the gable edges add up. A 48 ft front with one modest gable already needs about 82 ft of lights.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

A short window still takes a whole set

A 3 by 5 ft window needs 17.6 ft with slack. Sets come whole, so a 20 ft set does it with a little to tuck behind the frame, and a 25 ft set leaves a lot.

More plug points than you expected

Each window, door and rail starts at its own cord, and a long roofline splits when it passes the tag limit. Put the plan on paper before you buy cords.

What to record

Write the plan down once and next year is a 10 minute job. The printable sheet has a row for each run on the house:

  • Run (front eaves, left gable, porch rail, window 1) and its length in feet
  • Lit length and bulb type of the set that goes there, and how many sets
  • Most sets end to end from the tag, and which outlet or cord the run starts from
  • Clips used and how many, and any hooks left up from last year
  • Bushes and trees: size, nets or sets, and lights per set
  • Storage box or bag number for each run, so the right sets come out first
  • Date up, date down, and sets that failed or were replaced

Open the printable holiday lights plan sheet

Holiday lights plan sheet

Variants

Variant 01

A ranch with no gable

Leave the gables at 0. Measure the eaves along the ground under the gutter, from corner mark to corner mark, and add any side runs you can see from the street.

Variant 02

Two or more matching gables

If the peaks are the same width and height, enter the count and the tool multiplies. A smaller dormer is a separate run: work it out on its own and add the result to the straight eaves.

Variant 03

Windows only, roof left dark

Set the eaves and gables to 0 and fill in the windows, the door and the rail. Plug points then count one per window, because each window starts at its own cord.

Variant 04

Net lights instead of strings on hedges

For a long hedge, enter it as one bush: 20 ft by 3 ft is 60 sq ft, which is 3 nets.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

Numbers this tool uses

Limitations

  • Planning estimate; check the manufacturer's tag on each set for the lit length and the most sets end to end, and measure your own house.
  • This tool counts feet, sets and starting points. Choosing outdoor cords and outlets is outside it: read the label on each cord and set, and use a licensed electrician where the law requires one for outlet work.
  • It measures from the ground only. Hanging lights on a roof or a high gutter means ladder work; if that is not a job you do, hire a light installer.

Tips and tricks

  • Tip 01

    Mark the ground in daylight

    Do the measuring on a bright afternoon. Leave the chalk or stone marks until the lights are up, so you can check a run against the plan.

  • Tip 02

    Count siding rows for the rise

    Lap siding is the same height row after row. Measure one row at the bottom, count the rows from the eaves to the peak, multiply.

  • Tip 03

    Label each set when it comes down

    Tie a tag on the plug end with the run name from your sheet. Next year the front eaves sets come out of the box first.

  • Tip 04

    Test each set on the ground

    Plug each set in on the ground before it goes up, and replace a dead set while it is still in your hands.

What we would do

Plan the front from the street, then buy once

Measure the eaves and gables from the ground, run the tool, and buy all the roofline sets in one order from the same product. Do windows and the door with smaller sets. Fill in the printable sheet as the lights go up, so taking them down and putting them up next year follows the same plan.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

Questions

How many feet of Christmas lights do I need for my roofline?

The length of every run you want lit, plus 10%. A 48 ft front with one 24 ft gable that rises 6 ft has 74.8 ft of edge, so plan on 82.3 ft: four 25 ft sets.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

How do I measure the roofline without a ladder?

Stand under each corner of the gutter, mark the ground below it and tape between the marks. For a gable, tape the width at the eaves and estimate the rise by counting siding rows; the tool turns that into the two sloped edges.

How many sets of lights can I connect end to end?

The number printed on the tag of that set. It differs between sets; 1000Bulbs says it is usually 3 on the sets it describes. The tool asks for it and has no default.

Source: 1000Bulbs holiday lighting guide, checked October 9, 2026; Christmas Light Emporium planning guide, checked October 9, 2026.

How many lights do I need for a 7 ft tree?

About 700, at roughly 100 lights per foot of height: seven sets of 100. Add more for a full, wide tree and fewer for a slim one.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

How many net lights for a bush?

Multiply the width by the height of the side people see and divide by 24, the square feet a 4 by 6 ft net covers. A 4 by 3 ft bush takes one net; a 20 by 3 ft hedge takes three.

Source: Christmas Light Emporium planning guide, checked October 9, 2026.

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