Running costs · price cap 1 July to 30 September 2026
How much does a desktop computer cost to run?
A desktop computer rated at 140 W uses 0.14 kWh an hour, which costs about 3.7p an hour at the current price cap of 26.11p per kWh. Used for 4 hours a day, that is 15p a day, £4.39 over a 30-day month or £53.37 a year.
Prices checked against Ofgem on .
Per hour
3.7p
140 W
Per day
15p
for 4 hours
per year
£53.37
at 4 hours a day
Unit rate
26.11p
per kWh, price cap
Desktop computer running cost by time used
At 140 W and 26.11p per kWh. The week and year columns assume the same use every day.
| Time on | Per day | Per week | Per year |
|---|---|---|---|
| 10 minutes | 0.61p | 4.3p | £2.22 |
| 30 minutes | 1.8p | 13p | £6.67 |
| 1 hour | 3.7p | 26p | £13.34 |
| 2 hours | 7.3p | 51p | £26.68 |
| 4 hours | 15p | £1.02 | £53.37 |
| 8 hours | 29p | £2.05 | £106.74 |
Desktop computer running cost by electricity price
Monthly and yearly cost at the same usage. Fixed deals vary, so check the unit rate on your bill.
| Tariff | Unit rate | Per month | Per year |
|---|---|---|---|
| 1 July to 30 September 2026 price cap | 26.11p | £4.45 | £53.37 |
| 1 October to 31 December 2026 price cap | 26.32p | £4.48 | £53.80 |
| A 20p per kWh fixed deal | 20p | £3.41 | £40.88 |
| A 24p per kWh fixed deal | 24p | £4.09 | £49.06 |
| A 30p per kWh fixed deal | 30p | £5.11 | £61.32 |
How the cost is worked out
Watts ÷ 1,000 × hours × unit rate. For this desktop computer: 140 ÷ 1,000 × 1 hour × 26.11p = 3.7p an hour. Check the rating plate on your own desktop computer, as models vary.
From 1 October
The price cap changes to 26.32p per kWh from 1 October to 31 December 2026. At the usage above, a desktop computer would cost £53.80 a year, 43p more than now.
Guides and definitions
- Energy price cap explained: rates from 1 October 2026 and your bill (Guide)
- Is Economy 7 worth it? Hours, price cap and the night-use break-even (Guide)
- Standing charge vs unit rate: which energy tariff is cheaper for you? (Guide)
- Economy 7 (Economy 7 is an electricity tariff with seven cheaper off-peak hours, usually overnight, and a dearer daytime rate; Ofgem assumes 42% of use falls off-peak.)
- Typical domestic consumption values (TDCVs) (Typical domestic consumption values are Ofgem's yearly usage figures for a typical home, 2,500 kWh electricity and 9,500 kWh gas from 1 July 2026.)
- Energy price cap (The energy price cap is Ofgem’s limit on unit rates and standing charges for default tariffs; typical bill £1,723 from 1 October 2026.)
- Standing charge (A standing charge is the fixed daily amount on an energy bill, paid whatever you use; the capped average is 54.83p a day for electricity.)
Other appliances
- Electric hob (running costs)
- Hairdryer (running costs)
- Iron (running costs)
- Toaster (running costs)
- Vacuum cleaner (running costs)
- Heated towel rail (running costs)
- Electric blanket (running costs)
- Games console (running costs)
- Laptop (running costs)
- Broadband router (running costs)
Appliance running cost calculator · Use your own wattage and unit rate
Common questions
How much does a desktop computer cost to run per hour?
About 3.7p an hour for a 140 W model at 26.11p per kWh.
How much does a desktop computer cost to run a day?
About 15p if you use it for 4 hours. Double the time and the cost doubles.
How many watts does a desktop computer use?
The Centre for Sustainable Energy gives an average rating of 140 W. Yours will be on the label or rating plate.
Sources and assumptions
- Prices use the Ofgem price cap for 1 July to 30 September 2026: 26.11p per kWh, the average for Direct Debit customers in England, Scotland and Wales. Northern Ireland is not covered by the cap.
- Power ratings are the average figures published by the Centre for Sustainable Energy. Check the label on your own appliance for its wattage.
- The daily standing charge (57.19p a day) is paid whatever you use, so it is not included.
- Ofgem: energy price cap unit rates and standing charges
- Centre for Sustainable Energy: how much electricity am I using? (reviewed July 2026)
These are estimates. Your bill depends on your tariff, your region and how you use the appliance.