How much do incandescent Christmas tree lights (500 bulbs) cost to run?
About 5.4p an hour in the UK and 3.7¢ an hour in the US. Incandescent Christmas tree lights (500 bulbs) draw about 204 W for as long as they are on. The old bulbs draw about six times what LEDs do for the same tree, and run hot.
What they cost, by how long they run
| Running for | kWh | UK | US |
|---|---|---|---|
| 10 minutes | 0.034 | 0.89p | 0.62¢ |
| An hour | 0.2 | 5.4p | 3.7¢ |
| An 8-hour night | 1.63 | 43p | 30¢ |
| A full day (24 hours) | 4.9 | £1.29 | 90¢ |
| A month at 8 hours a day | 48.96 | £12.89 | $8.98 |
UK prices use the Ofgem price cap for 1 October to 31 December 2026 (direct debit, average across England, Scotland and Wales, with no VAT on electricity this winter): 26.32p per kWh (Ofgem). The standing charge of 54.83p a day is paid whatever you run, so it is left out. US prices use the US average residential price for June 2026 from the Energy Information Administration: 18.34¢ per kWh (EIA). Your own tariff is on your bill; scale the figures by it.
Measure your own
These are typical figures for a typical unit. A plug-in energy monitor between the socket and the appliance shows the real watts and adds up the kWh, so after a day or a week you know exactly what it costs on your tariff.
Compared with similar appliances
| Appliance | Average W | UK per hour | US per hour |
|---|---|---|---|
| Baby monitor | 6 | 0.16p | 0.11¢ |
| Aquarium, 100 litre | 24 | 0.63p | 0.44¢ |
| Hair straighteners | 24 | 0.63p | 0.44¢ |
| LED Christmas tree lights (500 bulbs) | 35 | 0.92p | 0.64¢ |
| Garden inflatable (Christmas or Halloween) | 50 | 1.3p | 0.92¢ |
| Dehumidifier, 12 L/day | 150 | 3.9p | 2.8¢ |
| Well pump (1/2 hp) | 200 | 5.3p | 3.7¢ |
| Cordless mower battery charger | 200 | 5.3p | 3.7¢ |
| Incandescent Christmas tree lights (500 bulbs) | 204 | 5.4p | 3.7¢ |
| Sump pump | 240 | 6.3p | 4.4¢ |
| Heated clothes airer | 300 | 7.9p | 5.5¢ |
| Hair dryer | 1,800 | 47p | 28¢ |
| Electric car (3-pin "granny" charger) | 2,300 | 61p | 26¢ |
Running it in a power cut
See which power station will run incandescent Christmas tree lights (500 bulbs), and for how long.
Appliance draw modelled on www.christmaslightsetc.com. The retailer’s wattage page puts 1,000 incandescent mini lights at about 408 W, so 500 is about 204 W.
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