Do Smart Plugs Save Energy?

Smart plugs get sold on two promises: convenience, which they deliver completely, and energy saving, which is where the claims get vague. The vagueness is not entirely the industry’s fault — the honest answer really is “it depends” — but it depends on things you can check in about ten minutes.

The principle is simple. A smart plug does not make anything more efficient. It makes things switch off. So the saving is entirely determined by what you are switching off, and how much that thing was costing while it was on.

Where the savings are real

Three categories, and they have something in common: a heating element, a motor or a compressor.

Heating appliances left running.Space heaters, towel rails, heated airers, a coffee machine keeping a jug warm all morning. These draw substantial power whenever they are on, and they are very frequently on when nobody is benefiting. Putting one on a schedule — or on an away-from-home trigger — is the clearest saving a smart plug produces.

Old appliances running continuously. A second fridge or chest freezer in a garage that is half empty, a dehumidifier running around the clock, an aquarium pump on a system that does not need one permanently. The plug lets you run these on a duty cycle rather than constantly.

Entertainment systems that never fully sleep. A games console, an amplifier, a soundbar and a TV on one plug can draw a surprising amount doing nothing, and unlike a modern LED lamp there is real power involved. One plug switching the whole cluster overnight is a genuine reduction.

Where they will not save you anything

Being equally clear about this is the point of the page.

The last two rows are warnings rather than advice. Never put your router, your smart-home hub or your alarm base station on a smart plug — the one time it switches off unexpectedly is the time everything else stops working. And appliances with internal clocks or programs lose them when the power is cut, which turns a small saving into a daily irritation.

The plug uses power too

Worth stating because it is rarely mentioned. A smart plug keeps its Wi-Fi radio awake continuously so it can receive the command to turn on. That draw is small, but it is not zero, and it is constant.

Which means fitting a smart plug to something that already drew almost nothing on standby can leave you marginally worse off than before. That is not an argument against smart plugs — it is an argument against fitting them to everything indiscriminately. Put them where there is a real load to control, and use them elsewhere for convenience with your eyes open. Our running cost guide puts this alongside the other always-on devices in a connected home.

Measure instead of guessing

The genuinely useful feature on a smart plug is not the switching — it is the energy monitoring that many of them include. Rather than relying on published averages for a category, you can put a plug on the suspicious appliance, leave it a week, and read what that specific device in your specific house actually drew.

We would rather you did that than trusted a number from anyone, including us. Standby draw varies enormously between a five-year-old appliance and a new one, and between models within the same category. A week of measurement settles it for your house permanently, and it usually produces one or two genuine surprises — which are exactly the appliances worth automating.

The plugs we would buy

Both of these are cheap in multipacks, need no hub, and work as simple Wi-Fi devices — which is what you want for something that should just work for years.

The bigger energy lever, for context

If reducing energy use is your actual goal rather than a nice side effect, smart plugs are not where the money is. Heating and cooling dominate household energy in most homes, which is why the U.S. Department of Energy and ENERGY STAR both focus their connected-device guidance on thermostats and scheduled setbacks rather than on switching individual appliances.

A smart thermostat that stops you heating an empty house addresses a far larger number than a plug on a coffee machine. Our do smart thermostats save money? guide covers what the federal sources actually support, and the best smart thermostatsroundup covers the hardware. Buy the plugs for convenience and for the two or three appliances where they genuinely help — and buy the thermostat if the bill is the reason you are here.

The honest verdict

Smart plugs save energy on appliances that draw real power and are sometimes on when nobody needs them, and on nothing else. Heaters, old fridges, dehumidifiers and entertainment clusters: yes, measurably. Lamps, chargers and low-draw electronics: no, and the plug’s own standby draw makes the case weaker still.

The right way to buy them is to get a multipack, put one on each suspect appliance, read the energy monitoring for a week, and then decide what to automate. That approach costs very little, tells you something true about your own house, and leaves you with plugs on the lamps as a bonus. They are also, incidentally, one of the best first smart-home purchases anyone can make for reasons that have nothing to do with energy — see our beginner picks for why.