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ENERGY CALCULATOR

Standby Power Cost Calculator

Use this standby power cost calculator to estimate the yearly electricity cost of always-on and idle devices. Enter your own values, then select Calculate to see the result.

Reviewed Oct 15, 2026Formula shownRuns in your browser

Your inputs

Change any value. Use one currency consistently for all money fields.

W
/kWh

Enter your numbers, then tap Calculate.

The currency selector changes the displayed symbol only. It does not convert exchange rates.

Your result

A transparent estimate based on the assumptions you enter.

Annual standby cost
—
Estimate only. Check the explanation and limitations below.
FormulaAnnual standby cost = standby watts × 24 × 365 ÷ 1,000 × electricity rate.

What this result means

This treats standby devices as continuously drawing the wattage you enter for a full year.

How the Standby Power Cost Calculator works

Measure standby draw with a plug-in energy meter for a more accurate estimate.

The calculator does not fetch live prices or rates. That is intentional: you provide the tariff, price, rate or cost that actually applies to your situation, which makes the assumptions visible and avoids presenting stale market data as current.

How to get a more useful estimate

  • Measure several always-on devices together with an energy meter if possible.
  • Focus on devices with continuous draw, such as decoders, routers, chargers, and entertainment equipment.
  • If a device is unplugged for part of the day, adjust the assumed hours using the appliance-cost tool instead.

Scenario check

Measure several always-on devices if possible, because small individual loads can add up across a home or office. The calculator assumes the entered standby wattage runs all day, every day. If a device enters deeper sleep or is switched off for part of the year, reduce the wattage or hours through a separate scenario instead of treating 24/7 as exact.

Important limitations

  • The model assumes 24-hour standby throughout the year.
  • Some electronics enter deeper sleep states and draw less over time.
  • The calculator does not value convenience or functionality provided by always-on devices.
Planning note: SmartCostTools provides educational estimates, not personalized financial, tax, legal, engineering, energy, lending or professional advice. Verify major decisions with current local information and qualified professionals where appropriate.

Frequently asked questions

Is standby power really significant?

For one efficient device it may be small, but many devices drawing power continuously can add up over a year.

Can I enter the total wattage of several devices?

Yes. Add their measured standby wattage and enter the combined figure.

Does a charger use power with nothing connected?

Many modern chargers draw very little when idle, but the exact amount varies. Measurement is the best way to know.