Four terms that are not interchangeable
| Term | Plain-language meaning in this site | Interpretation |
|---|---|---|
| Standby | Low-power state while connected and not performing the scheduled primary task. | May still provide displays, sensing, remote wake, memory, or controls. |
| Sleep | Reduced-power state designed for quicker return to active use. | Can preserve sessions, networking, updates, or wake functions. |
| Connected-idle | Low activity while remaining available to a network or remote service. | Loss of power can break communications or dependent services. |
| Always-on operation | The device is continuously performing its intended service. | Do not relabel operating power as avoidable standby. |
Standby formulas and units
annual standby cost = annual standby kWh × electricity price per kWh
Watts describe power at a moment. Watt-hours and kilowatt-hours describe energy accumulated over time. The rate must be a price per kilowatt-hour in the selected currency.
Worked illustrative example
| Inputs | 5 W standby × 20 h/day × 7 days/week at $0.20/kWh |
|---|---|
| Annual energy | 5 × 20 × 7 ÷ 7 × 365 ÷ 1000 = 36.500 kWh |
| Annual cost | 36.500 × $0.20 = $7.30 |
$0.20/kWh is an illustrative comparison input, not a national or current market price.
Labels, measured watts, and measured kWh
- Label value: useful when it clearly describes input power, but a maximum rating may not describe a low-power state.
- Measured watts: useful for a stable state; record what the device was doing and what accessories were connected.
- Measured kWh: useful across cycling or fluctuating states; divide energy by elapsed hours to obtain mean power for that period.
Measure long enough to include representative behavior. A five-minute sleep reading cannot establish a full day that includes updates or wake events. Measured active use does not automatically measure standby; measure standby separately or use a complete-period kWh reading without adding it twice.
Safety-first eligibility
| Eligibility | Current examples | Required action |
|---|---|---|
| Eligible only after explicit user confirmation | Televisions, game consoles, washing machines, laptops, and custom appliances | Mark Yes only after checking instructions, ratings, schedules, and required recording, updates, wake, charging, leak-protection, or other functions. Some presets also require the separate suitability checkbox. |
| Not eligible by default | Refrigerators, Wi-Fi routers, space heaters, and air fryers | Do not include them in scheduled-disconnection savings or show smart-plug economics. Edited standby watts do not override the policy. |
| Unknown | An unidentified appliance, lamp, smart bulb, hub, or imported record without a valid decision | Keep Not sure; check manufacturer instructions and critical functions before changing eligibility. |
Gross savings, plug cost, and payback
Gross avoided standby energy is the device electricity no longer used during an eligible disconnection schedule. A smart plug can consume electricity continuously, so its operating cost is subtracted to obtain net annual savings. Purchase cost is separate. Payback months divide complete purchase cost by positive net annual savings. Five-year net benefit is five years of net annual savings minus the complete purchase cost.
If plug operating electricity equals or exceeds the avoided standby cost, net savings are zero or negative and there is no finite payback. Safety eligibility must be established before economics are shown.
Use the tools
- Open the standby-only calculator and choose its Standby only tab.
- Open smart-plug payback and choose its Smart plug payback tab after confirming eligibility.
- Open the local standby audit that excludes No and Not sure records from its gross 80% standby illustration.
Related appliance guidance: television · game console · washing machine · laptop · Wi-Fi router · air fryer · refrigerator · space heater.
Calculation details: methodology · accuracy guide · source register
Last reviewed: August 14, 2026