How much does an electric car (3-pin "granny" charger) cost to run?
About 61p an hour in the UK and 26¢ an hour in the US. An electric car (3-pin "granny" charger) draws about 2,300 W (1,400 W on a US supply) for as long as it is on. Not a real use case: even a 5 kWh station adds only around 10 miles of range and empties itself doing it. See the guide before you try.
What it costs, by how long it runs
| Running for | kWh (UK) | UK | US |
|---|---|---|---|
| 10 minutes | 0.38 | 10p | 4.3¢ |
| An hour | 2.3 | 61p | 26¢ |
| An 8-hour night | 18.4 | £4.84 | $2.05 |
| A full day (24 hours) | 55.2 | £14.53 | $6.16 |
| A month at 8 hours a day | 552 | £145.29 | $61.62 |
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 an electric car (3-pin "granny" charger), and for how long.
Appliance draw modelled on www.cse.org.uk.
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