Smart Plug Savings Calculator

Estimate whether reducing a device’s scheduled hours with a smart plug would change its electricity cost by a meaningful amount.

A cost estimate does not mean an appliance is suitable for a smart plug. Check the appliance load and the smart plug’s printed rating. High-heat appliances may require specific rated equipment and should not be automated casually.

Your inputs

Estimated change

Current monthly cost-
Automated monthly cost-
Monthly savings-
Annual savings-
Reduction in this device’s hours-
Simple payback-

What this calculator estimates

It subtracts one running schedule from another. Current hours minus after-automation hours, at the wattage and rate you enter, scaled by days per week across a 365-day year. Month equals year divided by 12. Buying a smart plug does not, by itself, save money. Only fewer powered hours, or a drop from a high-draw state to off, can change the bill.

If you only need the running cost of a device, use the Energy Cost Calculator first. Come back here when you have a specific cut in hours to test.

When scheduling can reduce consumption

Schedules help when a device would otherwise stay powered longer than anyone is using it: a floor lamp left until morning, a space heater that keeps a workroom warm after you have left, a window fan that does not need the overnight hours. The larger the wattage and the larger the cut in hours, the more visible the dollar change.

That pattern is the same one described in the guide to useful plug automations and the electricity-cost article. A schedule is a blunt instrument. It is reliable when the device has a predictable day.

When a smart plug may save almost nothing

A 5 W speaker that already sleeps, a modem that must stay on, or a lamp you already switch at the door will not move a monthly bill. If current hours and after hours are the same, savings are zero. If after hours are higher, the estimate will show an increase. The tool will not dress that up.

At $0.15 per kWh, cutting three hours from a 100 W load saves about $1.37 a month, or about $16.43 a year. That can still be worth a $15 plug if you value the automation. It is not a reason to expect the electric bill to look different at a glance.

Standby power versus running devices

A plug that cuts power at the outlet removes both the running load and the standby load for those hours. That is useful for a television, a game console, or a charger strip. It is the wrong tool for a device that must stay reachable: a router, a fridge, medical equipment. The beginner guide covers ratings and the devices that should stay off a plug. Browse the rest of the Smart Plugs hub for setup and compatibility.

Standby watts are small. A 2 W idle load, 24 hours a day, is about 17.5 kWh a year. At $0.15 that is under $3. Do not use standby math to justify a plug on a device you need available.

A realistic example

100 W, 8 hours a day now, 5 hours after a schedule, 7 days a week, $0.15 per kWh. You remove 3 hours, or 0.3 kWh, each day. That is $0.045 a day, about $1.37 a month, about $16.43 a year. Enter a $20 plug cost and simple payback is a little over 14 months, assuming you actually keep the shorter schedule.

Raise the load to a 1,500 W heater and the same three-hour cut is 4.5 kWh a day: about $20 a month at that sample rate. The dollars get serious only when both the wattage and the unused hours are large. Even then, confirm the plug is rated for that load before you treat the estimate as a plan.