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Holiday lights cost calculator
Put your strands, watts, and hours in: 8 strands at 30 watts, on 6 hours a night, cost $7.34 a month.
★ MONEY · HOME · HOLIDAYS
Holiday Lights Cost Calculator: 8 Strands Cost $7.34
On the defaults — 8 strands, 30 watts a strand, on 6 hours a night for 30 days — holiday lights cost $7.34 a month. This is the holiday lights tool: multiply strands by watts for the total, multiply by the hours and the days for the kilowatt-hours, and multiply by the electricity rate for the bill — a roofline that looks festive tells you nothing until the watts are counted.
What does $7.34 mean?
It means 8 strands at 30 watts a strand — 240 watts in all — left on 6 hours a night for 30 days use 43.2 kilowatt-hours, and at $0.17 a kilowatt-hour that is $7.34 on the month’s bill. The watts set the energy and the timer sets the bill: the same strands left on all night would cost roughly double, and the same display swapped to LED would cost roughly a sixth.
Output · formula · meaning
| Output | Formula | What it means |
|---|---|---|
| Total watts | strands × watts a strand | 240 — 8 × 30. |
| Energy (kWh) | watts × hours × 30 ÷ 1000 | 43.2 — 240 × 6 × 30 ÷ 1000. |
| Monthly cost | kWh × $0.17 | $7.34 — 43.2 × $0.17. |
Three things to check before you trust the number
First, check the watts against the strand tag: 30 watts must be the strand’s real draw, because an LED strand at 5 watts turns this whole display into $1.22, not $7.34. Second, check the rate against the electricity bill: $0.17 a kilowatt-hour is the default, and a bill at $0.25 turns the same display into $10.80. Third, check the hours against the timer: 6 hours must be the hours actually lit, not the hours the house is awake, because a display forgotten until morning runs double the counted hours.
Worked example
8 strands, 30 watts a strand, on 6 hours a night for 30 days. Total watts: 8 × 30 = 240 watts. Energy: 240 × 6 × 30 ÷ 1000 = 43.2 kWh. Cost: 43.2 × $0.17 = $7.34 a month. In practice that means the display costs less than a takeaway coffee a week — and the $7.34 figure is the one to use when a timer or an LED swap is weighed against this display.
Every branch, checked
At 12 strands, same watts and hours, the result is $11.02 a month, 64.8 kWh. At 50 watts a strand, same strands and hours, the result is $12.24 a month, 72 kWh. At 4 hours a day, same strands and watts, the result is $4.90 a month, 28.8 kWh. At 6 strands, same watts and hours, the result is $5.51 a month, 32.4 kWh.
The reverses, worked backwards
The strands behind $7.34 are 8 strands: at 8 strands the result is $7.34; at the lower neighbor it is $5.51; at the upper neighbor it is $9.18. The watts a strand behind $7.34 are 30 watts: at 30 watts the result is $7.34; at the lower neighbor it is $4.90; at the upper neighbor it is $9.79. The hours a day behind $7.34 are 6 hours: at 6 hours the result is $7.34; at the lower neighbor it is $4.90; at the upper neighbor it is $9.79.
What the defaults assume
The defaults assume 8 strands at 30 watts, on 6 hours a night for a 30-day month, at $0.17 a kilowatt-hour. They do not assume a second month, inflatables, projectors, or a rate that varies by time of day — an inflatable fan adds its own watts all night, so treat $7.34 as the lights-only cost for one month at this rate, not the whole December bill.
Who uses this
- A homeowner hanging lights: the $7.34 figure settles whether the display is a treat or a worry before a single hook goes up.
- A renter splitting a bill: the kilowatt-hours figure is the fair share of a shared display.
- A holiday decorator: the per-strand watts turn a client’s wish list into a quoted running cost.
- An energy saver: the LED comparison is the cheapest argument on the page: same glow, a sixth of the bill.
Accuracy & limitations
The arithmetic is exact for the inputs entered; the judgement is the strand watts, the true hours lit, and the rate on the bill. Real displays vary with timers forgotten, dimmers, and rates that change by hour — so treat $7.34 as the planning cost for 8 strands at a true 30 watts and a true 6 hours, and check one bill before quoting it to anyone else.
Cite this calculator
Bright Side Kit, “Holiday Lights Cost Calculator: 8 Strands Cost $7.34”, https://brightoolbox.com/holiday-lights-cost-calculator/, accessed 3 November 2026. Students and researchers: cite the calculator name, the page URL and the date you used it, and quote the defaults so the result can be checked.
Frequently asked questions
How much do 8 strands of holiday lights cost a month?
$7.34 on the defaults: 8 × 30 = 240 watts, 240 × 6 × 30 ÷ 1000 = 43.2 kWh, and 43.2 × $0.17 = $7.34.
How much cheaper are LED holiday lights?
Roughly six times cheaper: 8 LED strands at 5 watts are 40 watts, 7.2 kWh over the same month, and $1.22 at the same rate.
What if the lights stay on all night?
About double: at 12 hours a night the same display uses 86.4 kWh and costs $14.69 a month.
Does the month mean 30 days?
Yes: the calculator uses a 30-day month, so a display up for six weeks costs about one and a half times the monthly figure.
Where do I find the watts per strand?
On the strand’s tag near the plug, or the box: the watts printed there are the draw to enter, and a strand with no tag can be estimated from its bulb count and bulb type.
How do I cut the cost without taking lights down?
Put them on a timer: cutting 6 hours a night to 4 cuts the month from $7.34 to $4.90, and swapping to LED on top of that takes it under $1.