Smart plug standby savings calculator

How the calculation works

Standby power is a small, constant draw, so the math is simple: standby watts × hours cut per day × 365 ÷ 1,000 = kWh saved per year, then kWh × your rate = dollars. This is the same watts-and-hours method the Department of Energy gives for any appliance. The calculator then subtracts what the plugs themselves use, because a smart plug keeps its radio awake 24 hours a day even when the device behind it is switched off: plugs × plug watts × 24 × 365 ÷ 1,000.

Payback in months is the purchase cost divided by the net savings per month. The default case: a TV (1 W), a console in instant-on mode (10 W) and a sound bar (3 W) make 14 W of standby. Cut for 18 hours a day, that is 14 × 18 × 365 ÷ 1,000 = about 92 kWh, or $16.56 at 18¢. One plug using 0.8 W takes back about 7 kWh ($1.26), so the net saving is about $15.29 a year (the tool rounds each line separately). A $15 strip pays for itself in roughly 11.8 months.

A second case: a console alone (10 W) with one plug, power cut 20 hours a day, comes to 73 kWh, minus about 7 kWh for the plug, so $11.88 net a year at 18¢ and a payback of about 15.2 months. The 18¢ default reflects the EIA’s forecast of about 18.2¢ per kWh for the 2026 U.S. average residential price.

The wattages beside each device are typical starting points, not measurements. Lawrence Berkeley National Laboratory has reported worst-case devices drawing more than 20 W in standby and has pointed to 1 W or less as a reasonable target; NRDC has measured a console at roughly 9 to 10 W in an instant-on setting and under 1 W in an energy-saving setting. Your gear will differ, so replace the defaults with a meter reading when you can.

Common mistakes

• Counting a 1 W device as a big win. A constant 1 W costs about $1.58 a year at 18¢, and the plug uses nearly as much. Plugs pay off on loads of several watts, or on groups of devices behind one strip.
• Forgetting the plug’s own draw. It is small, but it is the reason very low-power devices are not worth switching off.
• Changing the console setting instead. If a console is the main load, the free fix is its energy-saving power mode: no purchase needed. Try that first, then see whether a plug adds anything.
• Cutting power to gear that needs it. DVRs, routers, refrigerators and alarms should stay powered. See which devices use the most standby power for what to cut and what to leave.
• Ignoring the hassle. If turning the gear off means a five-minute reboot every evening, the habit will not last. Save the plugs for equipment that wakes up quickly.

To read real numbers from your own devices, see smart plugs with energy monitoring.