Standby Power Calculator
Some devices draw electricity while idle or waiting, while others are intentionally always on. A continuous draw adds up over a year, but it is only waste if the device is providing no function you want.
Set the number of each device you have and add your unit rate to see what that costs over a year.
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The starting watts are editable site illustrations. Replace each active row with the standby or idle draw you measured, or the figure stated by its manufacturer.
The starting unit rate is Ofgem’s price-cap rate for GB average, Direct Debit, 1 July 2026 to 30 September 2026 (Ofgem). Use the rate shown on your own tariff if you have it.
145 kWh per year
16.5 W drawn continuously. Add your unit rate above to see the cost.
What standby power is
Standby power — sometimes called phantom load or vampire draw — is electricity used by a device that is switched off or idle but still connected. It keeps a remote sensor listening, a clock running, a network connection alive or a device ready to wake quickly.
It is different from the running cost of an appliance you are actually using. If you want to know what one wash cycle or one hour of television costs, the appliance electricity cost calculator is the tool for that. This page answers a different question: what are you paying for things you are not using?
What actually costs you money
A device category does not determine one standby draw. Network settings, wake features, age and model can all change it, and some equipment has several idle modes. The number to cost is the mode the device actually spends time in.
The calculation is direct: continuous watts multiplied by 8,760 hours, divided by 1,000, gives annual kWh. Multiply that by the pence-per-kWh rate and divide by 100 for pounds.
The calculator's starting wattages are site illustrations only. Replace them with a measured draw or a figure for the relevant mode in the device's documentation.
What is worth switching off
Not all standby is waste. A router that is switched off has no internet. A set-top box that is off cannot record. A freezer is not on standby at all. The saving only counts if the device was not doing anything you wanted.
Worth targeting:
- Games consoles, if you do not need remote downloads overnight.
- Set-top boxes for services you no longer watch.
- Printers, desktop computers and monitors overnight.
- Second televisions and sound systems in rooms rarely used.
Check the function before switching:
- Broadband routers and network equipment.
- Anything with a clock you rely on.
- Devices scheduled to record, download or update.
Measuring it yourself
Your own devices can differ by make, age, mode and settings. A plug-in energy monitor can measure suitable mains-powered equipment; use a long enough observation to capture any cycling or wake events.
A whole-home smart-meter baseline is not a standby measurement. It can also include refrigeration, heating controls, pumps, storage heaters and other loads that cycle or run on a schedule. Use it as a prompt to investigate, not as the wattage for the rows above.
For what that consumption looks like across the country, the typical energy use page carries the published UK figures.
Frequently asked questions
How much does standby power cost a UK household?
There is no single household figure. Enter the standby or idle watts for each device, multiply the combined draw by 8,760 hours to get watt-hours a year, divide by 1,000 for kWh, then apply your unit rate. The calculator performs those steps.
Which devices use the most on standby?
The answer depends on the model and operating mode. A router is normally an always-on device, while a television may have several standby modes and a console can be configured to keep network features active. Measure the relevant mode or use the manufacturer figure rather than relying on a device-category estimate.
Is it worth switching things off at the wall?
Use the measured draw and your unit rate to calculate the saving, then consider what function would be lost. A router, recorder or device performing updates may be doing useful work while idle. Follow the manufacturer’s safety and shutdown guidance rather than assuming every connected device should be switched at the wall.
Do smart plugs use power themselves?
Yes. Include the smart plug’s own measured or manufacturer-stated draw when comparing it with the load it controls. Without both figures, the calculator cannot establish whether adding the plug reduces total consumption.
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Written by
Rob Gibbs
Hi, I'm Rob, and I run Energy-Review.co.uk. I initially started this project in 2018 when I was looking to switch energy suppliers and found there wasn't a website that provided simple, data-backed reviews on all the suppliers available. Since then, I have spent a lot of time (too much, some may say!) looking at all publicly available data about each supplier and writing reviews using this information. These reviews are updated as regularly as possible, and any data is backed up by a source where necessary. I have also started writing guides on various energy-related topics, which hopefully you will find useful. If you find any issues, please use our contact form to let us know.