An indoor and outdoor iclever smart plug, and a GE smart plug.
Josh Hendrickson

Smart plugs are a great way to automate your dumb devices, like lamps, game systems, and coffee makers. They also promise energy and money savings. But will they save enough money to pay for themselves? Maybe eventually.

Smart Plugs Are Perfect For Simple Automation

We like smart plugs because they’re easy to set up and make for great automation. Just plug it into an electrical outlet and then plug something into it. You now have a smart outlet—use an app for the rest. No need to get out any tools, or play with electrical wiring.

You might think that smart plugs would be a great way to save energy too. After all, you can make sure whatever the smart plug controls aren’t left on all day long by setting up a simple schedule to turn things off when you leave. But it’s a bit more complicated than that. Many of your electronics are as energy efficient possible, to begin with, and at least in the United States, electricity is a fairly cheap resource.

RELATED: 5 Creative Uses for Smart Plugs

You Use Energy to Save Energy

The easiest way to save energy is to unplug your devices, but that’s inconvenient. Some things you need running often enough that walking around the house and plugging in everything would get old quick.

While connecting everything to a smart plug sounds like a money-saving solution at first, two factors are working against you. First, if your concern is vampire energy, well, that doesn’t cost you as much as you might think. Second, smart plugs draw power to work. That’s necessary when you think about it; your plug needs to connect to something (Wi-Fi, Z-wave, etc.), and it needs to listen for signals. Those might be timed signals from a schedule or one you send through an app or a voice assistant.

Thankfully smart plugs don’t consume much energy. We tested three different smart plugs with a Kill A Watt monitor, and after a half-hour of measuring the meter still showed 0.00 kilowatts used. Left plugged in long enough, eventually, we’d measure something but the use is pretty low.

But the same holds with vampire energy, in the past when we tried measuring how much energy a single device used when turned off, the only way we got results was by plugging in six devices.

So if you hope to prevent the vampire energy costs with a smart device, you should hold off. The low cost of vampire energy and the cost to run smart plugs will cancel each other out.

RELATED: Tested: Should You Unplug Chargers When You're Not Using Them?

Even Powerful Electronics are Energy Efficient

Kill a watt meter showing .15 kWh used.
Josh Hendrickson

Vampire energy isn’t the whole story, though. Do you tend to forget to turn things off? Do you come home to find you left the TV, Xbox, and surround system on for the entire day regularly? Smart plugs can help here. You can set a schedule to turn those devices off every morning and night. But it still won’t necessarily save you money or even pay for the smart plug itself.

As an example, we measured a power strip with 10 devices connected and turned on for a half-hour: an Xbox One X, a Nintendo Switch, controller charging bases for both systems, a surround sound system, a 60 inch TV with Netflix streaming, a Google Home hub, an Eero Wi-Fi router, a Synology NAS, and a Nvidia Shield TV.

Altogether those devices used 0.15 kilowatts (kW). According to the EIA, the average cost of electricity is 12.82 cents per kilowatt-hour (kWh). So if we left this set of devices running as is for an entire day and night, it would use about $1.10 of electricity.

It’s unlikely to leave all those devices on 24 a day, every day. So in a more likely scenario, if you left everything on every night for the eight hours you were sleeping, you’d spend about 32 cents each day. In that scenario, it would take 71 days for the Eufy smart plug to pay for itself. The time adds up when you stop being generous about how often you leave absolutely everything plugged in. But as you can see, it is possible a smart plug could pay for itself, and possibly even save you money in the long run.

How to Tell If A Smart Plug Will Pay For Itself

Frigidaire dehumidifier set to 45 humidity.
This dehumidifier uses a surprising amount of electricity.

If you intend to save money, skip over anything small. Your device chargers, for instance, don’t draw enough power to overcome the cost of the smart plug. Instead, aim for something that sees heavy use and is likely to require more energy. Then double check that you don’t already have a built-in option. In the example above, the Xbox and TV both have settings to turn off after a set of time, but the surround sound system does not.

In our case, a large dehumidifier in the basement seemed like a prime candidate for money savings. The basement it resides in is humid, and generally needs the dehumidifier to run five or six hours a day to prevent issues. But its humidity sensor doesn’t work well, and when left to its own devices, the dehumidifier will run all day and night.

Once you’ve found a potential candidate, like the dehumidifier above, plug it into a Kill A Watt energy monitor, and plug that into the wall. Wait either a half hour or an hour then press the kWh button. The Kill A Watt monitor’s display will show you the amount of electricity used in kilowatt-hours. Your next step is to do the math.

You need to determine how many kilowatts a device uses in an hour. Multiply that by the number of hours used each day. Then multiply that by the cost of kilowatt-hours in your area. That’s how much the device cost you to run each day. Next, decide how many hours you can cut back with a smart plug. Multiply that number of hours by the kWh figure from before, then the cost of kWh in your area. That’s how much you could save under ideal circumstances.

Sometimes the Savings Is Large

Kill a watt monitor showing .31 kWh used.
Josh Hendrickson

In the case of the dehumidifier, it used 0.31 kWh in a half hour. To make the math simple, we’ll double that to 0.6kWh in an hour. That means in a day; the humidifier uses 14.4 kilowatt-hours. (24 hours multiplied by .6 kWh).

Going back to our estimate of 12.82 cents a kWh, each day the humidifier costs $1.87 in electricity to run (we rounded up to 13 cents, so 14.4 kWh multiplied by 0.13). With a smart plug, we can cut the time the humidifier runs back to six hours. That reduces the electricity spent each day to 47 cents a day. (Multiply .6 kWh by 6 hours, then multiply that result by .13 cents).

Since this humidified really will run all day long, every day, the above numbers are closer to real life than the media center example. And by reducing the bill an estimated $1.40, the $23 Eufy Smart plug will pay for itself in about 17 days. And in the first month, it will save $18.20.

Automation Is Still the Best Feature

It’s possible that smart plugs may save you money. But for every place that math works out, there are probably two or three places it won’t. A smart plug with a coffee maker, a lamp, or the power strip you plug all your phones and tablets into probably won’t save you any money.

But you’ll still gain automation. Just because it doesn’t save money doesn’t mean scheduled outlets aren’t convenient. You could use timers and schedules to give the appearance of being home when you aren’t. And the ability to turn some lights on and off by voice, or from your phone is incredibly convenient.

So unless you know for a fact that you have energy-sucking devices that need controlling, it’s probably best to focus on the convenience of smart plugs and treat the potential money savings as a bonus. Nice if it’s there, acceptable if it’s not.

RELATED: The Best Smart Plugs

Josh Hendrickson Josh Hendrickson
Josh Hendrickson has worked in IT for nearly a decade, including four years spent repairing and servicing computers for Microsoft. He’s also a smarthome enthusiast who built his own smart mirror with just a frame, some electronics, a Raspberry Pi, and open-source code.
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