Quick answer: A 100-bulb string of LED mini lights uses about 5 watts, while the same string in incandescent bulbs uses about 40 watts. Lit 6 hours a night for a 40-night season, ten LED strings cost about $2.18 in the US and £3.16 in the UK, against about $17.47 and £25.27 for incandescent.
Modern LED lights have made even large displays cheap to run. Older incandescent strings and big inflatables are where the cost hides.
Christmas light running costs
| Lights | Power | Hours a day | US per hour | US per day | US for the season (40 nights) | UK per hour | UK per day | UK for the season (40 nights) |
|---|---|---|---|---|---|---|---|---|
| LED mini lights, 100 bulbs | 5 W | 6 | $0.001 | $0.005 | $0.22 | 0.1p | 0.8p | 32p |
| Incandescent mini lights, 100 bulbs | 40 W | 6 | $0.007 | $0.04 | $1.75 | 1.1p | 6.3p | £2.53 |
| LED C9 bulbs, string of 25 | 25 W | 6 | $0.005 | $0.03 | $1.09 | 0.7p | 3.9p | £1.58 |
| Incandescent C9 bulbs, string of 25 | 175 W | 6 | $0.03 | $0.19 | $7.64 | 4.6p | 28p | £11.05 |
| Inflatable yard decoration | 120 W | 6 | $0.02 | $0.13 | $5.24 | 3.2p | 19p | £7.58 |
Holiday lights cost calculator
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How to keep your display cheap
- Switch to LED. They use around a tenth of the power of incandescent mini lights and run cooler.
- Use a timer or smart plug so lights are only on in the evening.
- Watch the inflatables. Their fans run the whole time they are lit.
- Use outdoor-rated lights and cables outside, and don’t overload sockets or extension leads.
Frequently asked questions
Is it expensive to leave Christmas lights on all night?
For LED lights, not very: a 5 W string left on for 12 hours costs about $0.01 in the US or 1.6p in the UK. For incandescent C9 strings it adds up faster, and lights left on unattended are a fire risk.
How many watts do LED Christmas lights use?
Around 4 to 7 W for a string of 100 mini lights, depending on the model.
A real example: a full house display
A large outdoor display with 30 LED strings, a few LED projectors and an inflatable might draw about 150 W in total. Lit 6 hours a night for 40 nights, that is 36 kWh: about $6.55 in the US or £9.48 in the UK for the season.
The same display with older incandescent strings and floodlights could easily draw 1,200 W, or 288 kWh for the season: roughly $52.42 or £75.80. That difference is why replacing a big incandescent display with LED usually pays for itself within a few seasons.
How to check what your lights use
- Look for the wattage on the tag near the plug or on the box. It is usually given per string.
- Multiply by the number of strings you connect.
- For inflatables, projectors and animated figures, check the label: inflatables have a fan motor that runs all the time, often 60 to 150 W.
- Plug the whole display into a plug-in energy meter for one evening to see the real figure.
More questions readers ask
Are battery-powered lights cheaper?
Usually not. Disposable batteries cost far more per kWh than mains electricity. Rechargeable or solar lights are a better choice where there is no outlet.
Is it safe to connect many strings end to end?
Only up to the limit printed on the packaging. LED strings allow many more connections than incandescent ones, but mixing types can overload the first string.
Sources
- U.S. Energy Information Administration, Short-Term Energy Outlook.
- Ofgem, Energy price cap.
- Our methodology.