A smart plug with energy monitoring is one of the cheapest pieces of hardware that can pay for itself. Most cost less than a takeaway. Most also tell you, with reasonable accuracy, how much electricity any plug-in appliance is using — turning vague suspicions (“the dehumidifier seems to run forever”) into actual numbers (“that’s 3.2 kWh a day, costing me roughly 80p”). For a household that’s serious about understanding which appliances are quietly costing real money, this is the right starting tool.
What the better smart plugs do well, and what the worse ones do badly, has very little to do with the marketing and a lot to do with a small handful of practical things: the accuracy of the energy meter, the reliability of the app’s historical reporting, the size of the plug body (so it doesn’t block the next socket on a double outlet), and whether the manufacturer charges for features that should obviously be free.
What “energy monitoring” actually means on a smart plug
Almost every modern smart plug measures three things: instantaneous power draw (in watts), cumulative energy (in kWh) over a period, and on/off state. The decent ones store historical data daily, weekly, and monthly so you can see trends. The good ones let you export the data. The mediocre ones show today’s usage and lose everything if the plug loses Wi-Fi for a few hours.
Crucially, none of them measure absolute mains-feed accuracy to lab tolerances. Treat the readings as accurate to within a few percent — which is more than enough to make every useful decision. The dehumidifier is either drawing 200W or 600W; you don’t need three decimal places to spot the difference between a £20-a-month appliance and a £60-a-month one.
The kWh figure is the one that matters for bill maths. Multiply kWh by your unit rate (the price-cap-aligned figure most UK households pay around 24–28p per kWh in 2026, depending on supplier and tariff) and you get the cost. Most apps will let you set your unit rate and show estimated cost directly, which is convenient but only as accurate as the rate you put in.
How to pick the right one for your household
The key questions:
- How many do you need? One per appliance you’re investigating is fine. Six or more, and the case for a whole-home energy monitor (which clamps onto the meter tail and reports total usage) becomes stronger. Smart plugs are best for diagnosing individual culprits, not measuring everything.
- What’s the appliance’s wattage? Most smart plugs are rated at 13A / 3000W maximum, which covers nearly every domestic appliance. A few high-draw items (some heaters, pressure washers, kettles when paired with another draw on the same circuit) push close to the limit. For anything over 2500W sustained, check the plug’s spec.
- Does the plug body block adjacent sockets? This is the most underrated criterion. A bulky plug on a double socket means you can only use one outlet. Compact-body plugs are worth a small premium.
- Do you care about Matter support? Matter is the cross-ecosystem smart-home standard. If you want a single plug that works with Apple Home, Google, Alexa, and Samsung simultaneously, look for Matter compatibility. If you only use one ecosystem, native integration with that ecosystem is usually more polished.
- App quality matters more than spec sheets. Energy monitoring is only useful if you actually look at it. The apps with the best historical visualisations are the ones you’ll keep using; the apps with charts that reset weekly are the ones you’ll forget about.
The shortlist
| Smart plug | Best for | Compact body? | Ecosystems | Price band |
|---|---|---|---|---|
| TP-Link Tapo P110 / P115 | Most households, best app for the price | Yes (P115) | Apple, Google, Alexa, Matter on newer firmware | Budget |
| TP-Link Kasa KP125M | TP-Link households wanting Matter from day one | Yes | Apple, Google, Alexa, Matter | Budget |
| Meross MSS315 | HomeKit-first households on a budget | Yes | Apple Home, Google, Alexa | Budget |
| Eve Energy (Matter) | Apple Home households who want polish over price | Yes | Apple Home / Matter / Thread | Mid-range |
| Sonoff S60 / S60TPF | Tinkerers who want local control and integration with non-mainstream platforms | Yes | Google, Alexa, eWeLink, Home Assistant | Budget |
TP-Link Tapo P115 — the default for almost everyone
The Tapo P115 is the smart plug to recommend if you don’t have a strong reason to recommend something else. The body is genuinely compact, so it doesn’t block the second outlet on a double socket. The Tapo app is mature, the historical energy view is clear, and the unit-rate cost calculation is set up properly. Tapo’s wider ecosystem — cameras, doorbells, sensors — slots in cleanly, which matters if you might add more devices later.
The P110 is the same plug at a slightly lower price point with a marginally bulkier body; if you can find them at similar prices, take the P115. Newer firmware versions support Matter, which extends the plug’s lifespan in households that change ecosystems.
The compromise is one Tapo shares with most cheap Wi-Fi devices: the cloud is part of the system. Most features still work locally over your network, but if Tapo’s cloud has a bad day, schedules and remote access can suffer. For energy monitoring specifically, the data is logged on the plug and synced when the cloud comes back, so you don’t lose history.
View TP-Link Tapo P115 Smart Plug options on Amazon
Check current price and bundle options on Amazon
TP-Link Kasa KP125M — the polished alternative
Kasa is TP-Link’s older smart-home brand, sitting above Tapo in price and (arguably) polish. The KP125M is the Matter-native version of Kasa’s energy-monitoring plug, and it’s the right pick if you want Matter support from the box rather than waiting on a firmware update. App quality is comparable to Tapo. Build feels slightly more substantial. The energy reporting is detailed and stable.
The reason most households should pick Tapo over Kasa is price. The Kasa premium is real and the practical difference for energy monitoring is small. The reason a household might pick Kasa over Tapo is consistency — if your existing TP-Link kit is Kasa, staying in-app is more comfortable than mixing.
Check TP-Link Kasa KP125M Smart Plug price on Amazon
Meross MSS315 — the HomeKit-first budget pick
If your household is built on Apple Home, Meross is the brand that’s done the work to make HomeKit integration painless on cheap hardware. The MSS315 sets up via the Home app, reports power and energy through Home, and supports automations alongside the rest of your HomeKit kit. The Meross app exists if you want richer historical reporting, but you don’t have to use it.
The downside is the same as any HomeKit-first plug: if you don’t use HomeKit, you’re paying for capabilities that don’t add value, and the Meross app is functional rather than excellent compared to Tapo or Kasa. For non-HomeKit households, pick something else.
See Meross MSS315 Smart Plug on Amazon
Eve Energy (Matter) — the premium HomeKit / Matter pick
Eve makes the smart plug equivalent of a Bose speaker — more expensive than the alternatives, slightly better thought through, and disproportionately appreciated by the people who buy it. The Eve Energy works over Thread (so it doesn’t add load to your Wi-Fi), supports Matter for cross-ecosystem use, and produces the clearest energy-monitoring visualisations of any plug on this list.
It’s the right choice for Apple Home households who want a plug that feels good to use and doesn’t behave like a budget product. It’s the wrong choice for households that just want a £10 plug to find out how much the dehumidifier is costing — the value proposition doesn’t survive that question.
Compare Eve Energy Matter Smart Plug options on Amazon
Sonoff S60 — the tinkerer’s pick
Sonoff is the brand that turns up when you ask a Home Assistant user what they bought. The hardware is cheap, the firmware is open enough to flash with custom versions, and the S60 series — including the energy-monitoring variants — works with eWeLink, Home Assistant via the Sonoff integration, and the major voice ecosystems. Local control is more thoroughly supported than it is on most cheap plugs.
For non-tinkerers, Sonoff is pointless. The default app is fine, the energy reporting is fine, but there’s nothing it does in mainstream use that Tapo doesn’t do as well or better. The reason to buy Sonoff is specifically because you want local-first control or because you’re feeding the data into a custom dashboard.
View Sonoff S60 Smart Plug options on Amazon
Where smart plugs actually save money (and where they don’t)
Smart plugs are diagnostic tools first. They tell you what an appliance costs to run. The savings come from what you do with that information — not from the plug itself.
The high-value targets in a typical UK household are usually:
- Tumble dryers and electric heaters. Heating elements draw a lot. A smart plug confirms exactly how much, and informs whether the tumble dryer or a heated airer paired with a dehumidifier is the cheaper way to dry clothes in winter.
- Old fridges and freezers. A 1990s freezer is often costing far more than a new one. A smart plug for a week tells you the kWh. A new energy-rated freezer will pay back the difference faster than people expect.
- Game consoles and PCs left on standby. A smart plug catches the standby draw. If it’s high, an automation that cuts power overnight saves money without inconvenience.
- Aquarium pumps, dehumidifiers, and other always-on appliances. Anything running 24/7 is worth measuring once. The cheap appliances often turn out to be expensive over the year.
Where smart plugs do not save money is on appliances they can’t measure (anything hard-wired into the consumer unit), on devices that don’t have meaningful standby load (a phone charger plugged in but not charging draws negligible power), and on households who aren’t going to look at the data after week one. If you know yourself well enough to know that’s you, buy a different smart-home toy.
For the bigger picture of where home energy goes, smart plugs pair well with thermal curtains and draught proofing and smart radiator valves or thermostats — the former addresses heat loss, the latter addresses heating cost, and smart plugs cover the long tail of plug-in appliances. Together they’re a coherent set; alone, each is a partial answer.
Frequently asked questions
How accurate are the energy readings? Within a few percent of true for the plugs in this guide. That’s plenty for any practical decision. Don’t expect lab-grade accuracy — and don’t pay extra for it on a domestic smart plug.
Will smart plugs work with my router? All the plugs here use 2.4GHz Wi-Fi (not 5GHz). Most modern UK routers broadcast both bands and the plugs find the 2.4GHz network automatically. Some mesh systems require you to temporarily separate the bands for setup. Check your router’s setup guide if the plug won’t connect; it’s almost always a 2.4GHz issue, not a faulty plug.
Can I run a fan heater or kettle through one? Up to the plug’s rated capacity, yes. The plugs here are 13A / 3000W — covering most domestic appliances. Fan heaters at 2000W are fine. A kettle at 2400W is fine. Avoid running multiple high-draw appliances through a single plug via an extension.
What about Matter? Should I wait for it? If your existing smart-home kit is already in one ecosystem, Matter doesn’t change much in the short term. If you’re starting fresh or might switch ecosystems, prefer a Matter-supporting plug — but don’t pay a large premium for the badge. Most plugs in this guide either support Matter or will via firmware updates.
Is there a privacy concern with cloud-connected plugs? The data being sent is essentially “this plug is on” and “this plug used X watts in the last interval.” It’s not a privacy emergency, but it’s not nothing either. If you specifically want local-only operation with no cloud component, look at Sonoff (with custom firmware) or the Matter-over-Thread route via Eve.
The recommendation, in plain terms
Buy the Tapo P115 unless you have a reason to do something else. It’s the right combination of compact body, solid app, accurate enough energy reporting, and competitive pricing. If you’re a HomeKit-first household, Meross MSS315 is the cheap pick and Eve Energy is the polished one. If you specifically want Matter-native, take the Kasa KP125M. If you’re running Home Assistant and want local control, Sonoff S60.
Buy two or three to start, point them at the appliances you suspect of running up the bill, and look at the data after a fortnight. That’s where the value is — not in the plug itself, but in what you do with what it tells you.