wb_incandescent
Christmas Outdoor Lights Calculator
The Christmas Outdoor Lights calculator estimates how many lights and light strings you need to line your roof, eaves or railings, based on the length you want to cover.
Last updated: June 2026 · Free · No sign-up required
Results
Enter values above and click Calculate to see your result instantly.
Quick reference
| Area | Typical length | @12 lights/ft |
|---|---|---|
| Single-storey roofline | 60 ft | 720 lights |
| Roofline + porch | 80 ft | 960 lights |
| Two-storey full outline | 150 ft | 1,800 lights |
| 6-ft shrub (wrapped) | — | ≈ 250 lights |
wb_incandescent Even coverage
Uses a sensible lights-per-foot density so the display looks balanced, not sparse.
cable Strings to buy
Converts the total into whole light strings for easy shopping.
bolt Avoid overload
Knowing the count helps you stay within the safe number of connected sets per circuit.
Interpretation guide
| Density | Look |
|---|---|
| 6–8 lights/ft | Light, classic outline |
| 10–12 lights/ft | Full, even coverage (default) |
| 15+ lights/ft | Dense, showpiece effect |
Formula & methodology
Formula: Lights = feet × lights-per-foot; strings = ⌈lights ÷ lights-per-string⌉
- Measure the linear feet to cover (roofline, eaves, railings, paths).
- Pick a density — 12 lights/ft gives even mini-light coverage.
- Enter your string size (100-count is standard) to get strings to buy.
Worked example: 80 ft at 12 lights/ft = 960 lights → ten 100-light strings. Check the box’s "max connected sets" — many mini-light strings cap at 3–5 per outlet run.
Authoritative source: Christmas lights — Wikipedia
Frequently asked questions
How many lights per foot of roofline?
Mini-lights: 10–12 per foot for full coverage, 6–8 for a lighter outline. C7/C9 bulbs are spaced one per 12 inches, so one bulb per foot plus a few spares.
How many strings can I connect end-to-end?
Incandescent mini-lights typically max 3–5 strings per run; LEDs often allow 40+ because they draw ~10× less power. The packaging states the limit — exceeding it blows fuses.
How many lights for a shrub or small tree?
Rule of thumb: 100 lights per vertical foot for a wrapped look — a 6-ft shrub takes ~250–600 depending on density. For trunks, one 100-count string covers about 3 ft of wrap.
How much power will my display draw?
Incandescent minis ≈ 0.4 W/bulb: 960 lights ≈ 384 W. LED equivalents ≈ 0.07 W/bulb ≈ 67 W. Keep total amps under 80% of the circuit (12 A on a 15 A circuit).
Should I buy extra lights?
Add ~10% for corners, peaks, and dead strings discovered in the box. Buying one spare string of the identical model avoids colour-temperature mismatches mid-season.