How this calculator works
Calculate the monthly and annual electricity cost of devices that remain on or in standby around the clock.
Why one watt matters over a year
A one-watt continuous load runs for 8,760 hours in a typical year. The cost is usually small for one modern device, but a group of network, entertainment, office, and control devices can create a persistent base load.
Measure before disconnecting
Nameplate wattage is often a maximum and may not describe standby use. A compatible plug-in energy meter can measure low-power operation over several days.
- Do not disconnect medical, safety, refrigeration, sump-pump, or security equipment casually.
- Check whether a device needs a controlled shutdown.
- Compare the annual savings with the cost and inconvenience of a control device.
Use the result to prioritize
Start with the largest measured continuous loads. Scheduling a home server or older set-top box can matter more than unplugging many devices with sub-watt standby consumption.
Frequently asked questions
Is standby power the same as idle power?
Not always. Standby usually means a low-power waiting state, while an idle computer or server may remain fully active at a higher draw.
How can I measure very small loads?
Use a meter rated to measure low wattage and record energy for a longer period so short cycling does not distort the result.
Should I unplug every device?
No. Prioritize meaningful, nonessential loads and preserve safety, updates, networking, and controlled shutdown requirements.
Use equipment documentation, your utility rate schedule, and measured data when they are available.