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Standby Power Cost Calculator

Enter the standby wattage and electricity rate to get the annual standby power cost.

Result

$10.51
70.08 kWh

How it is calculated

The tool assumes the device draws the same power every hour of the year. Yearly energy is kWh = W × 24 × 365 / 1000, where W is the standby draw in watts, and the yearly cost is kWh × rate, where rate is the price of one kilowatt-hour. Both inputs must be zero or more. Energy is shown in kWh with two decimals and the cost in dollars. Use the same currency for the rate as you want in the answer, since the tool does not convert currencies. The model counts 8,760 hours per year, so a device that is only plugged in part of the year will cost less than shown.

Worked example

A set-top box and TV combination draws 8 W on standby, and electricity costs 0.15 per kWh. Energy: 8 × 24 × 365 / 1000 = 70.08 kWh per year. Cost: 70.08 × 0.15 = $10.51 (10.512 rounded). So that small, always-on draw costs about ten dollars a year.

Try this example →

Common mistakes

  • Entering the rate per Wh or per MWh instead of per kWh; your bill states a per-kWh price.
  • Entering the device's running power instead of its standby power. Standby draw is usually far smaller and is on the label or measured with a plug-in meter.
  • Entering the rate in cents (15) rather than the main currency unit (0.15), which makes the cost 100 times too high.
  • Using one device's wattage for a whole room of devices without adding them up first.
  • Ignoring tiered or time-of-use tariffs; the tool applies one flat rate to every hour.

About this calculator

Standby power (also called phantom load or vampire power) is the electricity a device draws while switched off or idle — think TVs, chargers, game consoles, and set-top boxes still sipping power from the wall. The annual cost is standby wattage ÷ 1000 × 24 hours × 365 days × electricity rate, converting continuous watt draw into yearly kilowatt-hours and then dollars (or your local currency).

Individually small, standby loads add up across a household's many always-plugged-in devices, and studies have found phantom power can account for 5-10% of residential electricity use. Homeowners and energy auditors use this calculation to quantify exactly how much a given device costs to leave plugged in, and to prioritize which ones are worth switching off at the outlet or replacing with lower-standby models.

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Comments (1)

  • Editorial team

    The tool takes one total wattage, so group devices that share an outlet strip and enter their standby watts added together. Five devices at 2 W each make 10 W, about 87.60 kWh a year. Then compare the yearly saving with what a switched strip or smart plug costs, remembering that a smart plug itself draws a little power. Which devices in your home do you suspect of drawing the most while idle?

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