Holiday Lights Buying & Planning Guide
Product types, outdoor ratings, connection limits, installing safely and storing lights for next year.
What would you like to decorate?
Units
Roofline
ft
One continuous section you’ll lightruns
Same length, not connectedA run is one continuous section. Separate sections, like the garage and the house, each need their own strands.
What lights are you using?
Example strand · replace with your product’s numbersft
Example strand. Change it to match the lights you’re buying.bulbs
Not every 25-ft strand has the same bulb countColorColor changes the picture, not the count.
Not sure which lights to buy or how to hang them safely? Read the Holiday Lights Guide →
Your lighting estimate
Example strand · enter yours above
2 strands
of 25 ft to buy (example strand)
50 ftof lights needed
- Bulbs purchased
- 50 on 2 strands · 25 each, not all on the decorated areas
- Clips
- 51 one every 12 in plus one per run, outlines only
- Separate runs
- 1 one continuous section
in
Use your clip’s spacing. Clips are counted on outlines only.Roofline · 50 ft
You need 2 strands.
Those 2 strands fit your runs exactly, with no extra lit length.
How the strands fit each run
Each bar is one run and each segment one strand. The pale part is extra lit length: the lit section left over on that run’s last strand, which can’t be moved to another run.
Roofline1 run · 50 ft
2 strands · 0 ft extra litEverything you need to buy
| Item | Quantity | Price optional | Total |
|---|---|---|---|
| 25-ft warm white light strands25 ft lighted · 25 bulbs each · example strand, use your product’s numbers | 2 | $ per strand | — |
| Compatible mounting clipsOne every 12 in · match your gutter, shingle or railing | 51 | $ per pack | — |
Add to the list
- Strands
- 2
- Bulbs
- 50
- Lighted length
- 50 ft needed · 50 ft bought
- Clips
- 51
Estimated materialsAdd pricesEnter prices to see a materials subtotal. CalcBrite doesn’t track store prices.
More options
Your plan
Ready to light up your home?
Learn more
How do I calculate holiday lights for a roofline?
Measure each continuous section you’ll light, such as the front eave or the garage, as its own run. Divide each run by the strand’s lighted length and round up. Add the runs together only after rounding.
How many lights do I need for a tree?
It depends on the tree’s shape, how far apart you wrap the passes and how full you want it. CalcBrite estimates from the cone’s surface and your spacing, so treat the result as a starting point.
How many light clips do I need?
Divide each outlined run by your clip spacing, round up, and add one per run. Only outlines (rooflines, windows, doors and straight railings) get clips; wrapped railings, trees and shrubs take none. Clips are made for specific surfaces (gutters, shingles, railings, brick), so choose ones that fit where you’re hanging the lights.
Questions
Should I use LED or incandescent lights?
LED strings use far less electricity: ENERGY STAR certified decorative strings use about 92% less energy than incandescent strings. Whatever you choose, connect no more strands end to end than the label allows, and don’t mix products on one run unless the instructions say you can.3
How can I estimate holiday-light installation cost?
Installers price by the job. Share your areas, approximate footage, number of separate runs and whether you’ll supply the lights, then ask what’s included: lights, clips, installation, removal and storage. CalcBrite doesn’t estimate labor rates.
How many feet of holiday lights do I need for a house?
Add up the runs you plan to light: rooflines, window and door outlines, railings, trees and shrubs. Measure each one rather than guessing from the size of the house, and count each separate section as its own run.
Can I connect strands end to end?
Only up to the maximum the manufacturer states on the label or instructions. The Consumer Product Safety Commission says never to string together more than three sets of incandescent lights. Enter your product’s limit under More product details and CalcBrite flags runs that need more.1
What’s the difference between lighted length and cord length?
Lighted length is the section with bulbs. Cord or package length also includes the lead and tail wires, so it’s longer. Use the lighted length to plan.
How we calculate, assumptions & sourcesWorked example, formulas, safety limits, 5 sources
Worked example: a 35 ft roofline and two 3 × 4 ft windows, 25-ft strands
- Roofline 35 ft ÷ 25 ft = 1.4 → 2 strands
- Window 1: 2 × (3 + 4) = 14 ft → 1 strand
- Window 2: 14 ft → 1 strand
- Total lighted length = 63 ft; pooled 63 ÷ 25 = 2.52 → 3, but separate runs need 4 strands
- Clips (12 in): roofline 35 + 1 = 36; each window 14 + 1 = 15 → 66 clips
Formulas
- Roofline
- runs × run length
- Window or door
- all sides 2 × (width + height) · top and sides width + 2 × height · top only width
- Wrapped railing
- (length ÷ wrap spacing) × √(spacing² + distance around²)
- Tree (estimate)
- π × r × √(r² + h²) ÷ spacing between passes
- Shrub (estimate)
- surface of a half-ellipsoid dome (width × depth at the base, height = the dome’s height from the ground) ÷ row spacing; front only = half
- Strands
- Σ runs × ⌈ run length ÷ lighted length ⌉
- Clips
- Σ runs × (⌈ run length ÷ clip spacing ⌉ + 1), outlines only
- Electricity
- strands × watts × hours × days ÷ 1,000 = kWh; × rate
- Metric
- 1 ft = 0.3048 m · 1 in = 2.54 cm
Assumptions
- Each separate run gets whole strands; leftover length isn’t moved to another run.
- Strands aren’t cut, modified or connected beyond what the product allows. Never string together more than three sets of incandescent lights.1
- Bulbs and watts come only from the product details you enter.
- CO₂e uses the U.S. grid average, 0.77 lb (0.35 kg) per kWh; your utility’s may differ.5
- Trees and shrubs are estimates from shape and spacing; outlines are measured.
- Clip counts are for outlines; surfaces and clip types vary.
- A strand count isn’t a safety check. Use lights and extension cords marked for outdoor use outdoors, plug them into GFCI-protected circuits and don’t overload outlets.21 CalcBrite doesn’t size cords or approve electrical loads.
- All math uses full precision; results are rounded only for display. Unit conversions follow NIST.4
Sources
- Holiday Safety, U.S. Consumer Product Safety Commission — “Never string together more than three sets of incandescent lights and never overload electrical outlets.”.
- Outdoor Decoration Safety Tips, Electrical Safety Foundation International (ESFI) — extension cords and decorations marked for outdoor use; match amperage needs to the cord’s rating; plug outdoor lights into GFCI-protected circuits; inspect before use; fasten without damaging the insulation; ladders at least three feet past the roof edge; stay 10 feet from power lines; don’t overload outlets (industry source).
- Decorative Light Strings, ENERGY STAR (U.S. EPA) — certified decorative light strings use about 92% less energy than incandescent strings; products labelled for outdoor use are weathering tested; no more than 0.2 W per bulb.
- Guide to the SI, Appendix B.8: factors for units listed alphabetically, NIST Special Publication 811 — foot = 0.3048 m; inch = 2.54 cm.
- eGRID Summary Data (eGRID2023, revision 2), U.S. Environmental Protection Agency; June 2025 — U.S. average total output emission rate: 770.884 lb CO₂e per MWh (0.77 lb per kWh).
- Last reviewed:
- October 2026
- Last updated:
- October 31, 2026
- Calculator version:
- 1.0