Do Smart Plugs Use Electricity When Off: Standby Costs Explained

Why the plug stays powered even when the outlet is off

Switching a smart plug’s outlet off cuts power to whatever device is plugged into it — but not to the plug itself. The plug’s internal circuits stay energized so it can receive commands from your phone or a voice assistant at any moment. Standby power is the electricity a device consumes when switched off or not performing its primary function, according to Lawrence Berkeley National Laboratory’s standby power research program.

The same principle applies to any device that must respond to a remote signal. A smart plug that cannot hear your app’s command is useless, so it never truly powers down as long as it is plugged into the wall. As the Wikipedia article on standby power explains, that draw comes from internal power supplies, remote control receivers, and circuits that stay energized even when the device appears off.

How much standby power a smart plug actually draws

Berkeley Lab reports that most modern products draw less than 0.5 watts in standby — a significant drop from the 1–3 watts typical of devices made 20 years ago. Older devices can draw as high as 10–15 watts. No smart-plug-specific standby figure is confirmed in the available evidence, so treat 0.5 W as a reasonable upper-end reference for a current-generation device.

Standby loads from all connected devices in a home add up. According to Berkeley Lab, they account for 5–10% of residential electricity use in a typical American home.

What that standby draw costs per year

Each watt of continuous power consumption uses about 9 kWh of electricity per year (1 W × 24 hours × 365.25 days). At average US electricity rates, that works out to roughly $1 per year per watt of continuous draw.

Illustrative example: If your smart plug draws 0.5 W continuously in standby, it consumes about 4.4 kWh per year (0.5 × 8,766 hours), costing approximately $0.50 annually at average US rates. If you have ten smart plugs, that rises to roughly $5 per year — still modest, but measurable.

Your actual cost depends on your local utility rate, which varies by state and is not fixed at the average used above.

How to measure your smart plug’s actual standby draw

The most direct method is a plug-in wattmeter, sometimes called an energy monitor. You plug the wattmeter into the wall outlet, plug the smart plug into the wattmeter, then switch the smart plug’s outlet off while leaving it connected to your app. The wattmeter displays the real-time wattage the plug is drawing in that state.

Plug-in wattmeters start at around $10 and are an affordable way to check your smart plug’s draw. Some US public libraries and local utilities lend them at no charge. Keep one limit in mind: at very low wattages (under 0.5 W), cheaper meters can have large percentage errors. Treat the reading as a useful estimate, not an exact figure. A meter rated for RMS measurements gives more reliable results at low loads. For reference, IEC 62301 guidance calls for uncertainty of no more than 0.01 W when measuring loads below 0.5 W — a standard that requires lab-grade equipment, not a $10 consumer meter.

What you can do to reduce or eliminate the draw

The only way to eliminate a smart plug’s standby draw entirely is to unplug it from the wall — which also removes its ability to respond to commands. That trade-off defeats the purpose of the device.

More practical options, supported by standby power research:

• Use a switched power strip: Plug several smart plugs or other devices into a power strip that has a physical switch. One flip cuts standby power to the whole group without unplugging each device. This works best for devices in a room you leave unused for long stretches.
• Use a timer: A timer outlet can cut power to a smart plug on a schedule — for example, overnight — if you know you will not need remote control during those hours.
• Accept the cost for always-on devices: For plugs controlling devices you genuinely need to reach remotely at any time, the standby draw is the price of that convenience. At under 0.5 W per plug, the annual cost is typically less than $1 per plug at average US rates.

Switching off standby power may cause some devices to lose configuration settings, so check your smart plug’s app behavior before cutting power for long periods. For more on managing connected devices and home network power, see the Smart Home topic hub.