Key takeaways
- The Tapo P110 two-pack was number one in Amazon UK’s Smart & Remote Controlled Plugs chart and number 12 across the whole DIY & Tools department when we checked on 9 October 2026.
- All six best sellers we read are 13A plugs, yet their listings and spec sheets quote four different maximum loads: 2,860W, 2,990W, 3,250W and 3,680W. The number changes because each one assumes a different mains voltage, not because the hardware differs.
- The declared UK low-voltage supply is 230V with a permitted range of 216.2V to 253V, so the most a 13A plug can pass anywhere in that range is 3,289W. One listing in our six claims 3,680W alongside a 13A rating, which would need 283V.
- A smart plug’s reading carries no statutory accuracy class. Active electrical energy meters are regulated under the Measuring Instruments Regulations 2016 only when they are used for trade, which is your billing meter and not the plug in your socket.
Smart plugs sell hardest in the first cold weeks of autumn, and this year is no exception. When we read the charts on 9 October 2026 the Tapo P110 two-pack sat at number one in Smart & Remote Controlled Plugs and number 12 across the entire DIY & Tools department, with 54,155 ratings behind it. The Tapo TP11 four-pack was number two. People are buying them for one reason above all others: the October price cap has just landed and they want to know which appliance is eating the money.
That is a good instinct, and a plug-in meter is the cheapest way to answer it for a single socket. What nobody selling them explains is how to read the two numbers that matter, the maximum load printed on the box and the wattage shown in the app. We went through the spec sheets of the six best sellers and found that neither number means quite what it looks like.
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Prices and specs last checked by Look Into on 9 October 2026 · next check 4 December 2026 · how we picked
Every one of these is a 13A plug. The watts on the box are an assumed voltage
A UK three-pin socket is a 13A socket, and every smart plug in our six is rated at 13A. So the maximum load should be one number. It is not. TP-Link’s own product pages give 2,990W for both the Tapo P110 and the TP11. SONOFF’s spec sheet for the S60ZBTPG gives 3,250W. The Amazon spec table for the Tapo P110 two-pack gives 2,860W, while the description on that same listing says 2,990W. The ANTELA four-pack listing pairs a 13A current rating with 3,680W.
Watts are volts multiplied by amps, so a 13A ceiling only becomes a wattage once you decide what the voltage is. Work the numbers back and the four figures resolve into one plug described four ways: 2,860W is 13A at 220V, 2,990W is 13A at 230V, 3,250W is 13A at 250V, and 3,680W is 16A at 230V rather than 13A at anything plausible.
Only one of those voltages is the British one. Regulation 27 of the Electricity Safety, Quality and Continuity Regulations 2002 requires the declared low-voltage supply to be 230V between phase and neutral, with a permitted variation of 10 per cent above and 6 per cent below. That puts the legal range at 216.2V to 253V. At 13A, the absolute ceiling anywhere in that range is 3,289W, and the figure you should plan around is 2,990W.
Why it matters in practice: the spread between the lowest and highest claimed figure is 820W. A reader comparing a 2,860W plug against a 3,680W plug would reasonably think the second one has headroom for a bigger appliance. It does not. They are the same 13A device, and the 3,680W claim describes a supply voltage no British home is permitted to have.
There is a second limit the listings bury. TP-Link’s P110 page says EV charging is not supported because its charging current exceeds the plug’s rated current, and tells you to avoid appliances with a motor or compressor rated above 1/6 HP, naming air conditioners. If you are buying a smart plug to measure a fridge, a freezer, a dehumidifier or a portable air conditioner, check the manufacturer’s motor limit before you plug it in rather than after.
What the number in the app is not
The reading these plugs show you has no legal standing. Under the Measuring Instruments Regulations 2016, active electrical energy meters are a regulated category, but regulation 3(2) narrows that to meters “for use for trade”. Your supplier’s meter is one of those, and it has to meet an accuracy class and pass conformity assessment before it can bill you. A smart plug is not sold for trade use, so none of those requirements touch it, and no manufacturer in our six states an accuracy figure in its UK listing.
None of that makes them useless. It does mean using them for the job they are good at, which is comparing one appliance against another on the same plug, or the same appliance before and after you change how you run it. Treat the absolute pounds figure in the app as an estimate and the relative difference as the useful output. For whole-house numbers, your smart meter’s in-home display is the regulated instrument, and we have gone through those separately in our guide to energy monitors.
What a smart plug costs to run
A measuring device that costs more than it saves is a bad buy, so this is worth doing before you fill the house with them. SONOFF’s own FAQ for the S60 series puts smart plug standby draw at “usually below 1W”. Take 1W as the working figure. Left on all year that is 8.76 kWh, which at the current cap rate comes to £2.31. Buy the four-pack and run all four permanently and you are looking at £9.22.
Those are small numbers, and they are meant to be. The point is the comparison: a plug that costs a couple of pounds a year to run pays for itself the first time it shows you that a second fridge in the garage is costing forty times that. Our appliance running cost calculator and the UK Running Cost Index give you the figures to check a reading against once you have one.
All running costs on this page use the Ofgem price cap unit rate for the 1 October to 31 December 2026 period, direct debit average for England, Scotland and Wales, and update automatically when the cap changes.
How we picked these
We read the Amazon UK Smart & Remote Controlled Plugs and DIY & Tools charts on 9 October 2026 and took the six best-selling plugs we could verify, then opened every manufacturer spec sheet we could find for them. Each product page was checked for title, price, stock and the stated current and wattage ratings on the day. The legal figures come from the regulations themselves rather than from other people’s summaries. This is desk research: we have not taken these plugs apart or tested their measurement accuracy against a reference meter, and where we could not verify something we have said so.
At a glance
| Plug | Price | Per socket | Max load as stated | Energy monitoring |
|---|---|---|---|---|
| Tapo P110, 2-pack | £20.99 | £10.50 | 2,860W in spec table, 2,990W in description | Yes |
| Tapo P110, single | £9.00 | £9.00 | 2,990W, 13A | Yes |
| Tapo TP11, 4-pack | £44.99 | £11.25 | 2,990W, 13A | Yes |
| ANTELA, 4-pack | £29.99 | £7.50 | 3,680W alongside a 13A rating | Yes |
| SONOFF S60ZBTPG | £12.77 | £12.77 | 3,250W, 13A | Yes, Zigbee gateway needed |
| Amazon Basics smart plug | £9.99 | £9.99 | Not stated in the spec table | No |
One thing worth noticing in that table before you go any further. The single Tapo P110 at £9.00 is cheaper per socket than the two-pack at £10.50 and the TP11 four-pack at £11.25. Multipacks are usually the cheaper route and today they are not, so check the single’s price against the pack maths on the day you buy.
The six we would actually buy
Tapo P110 Smart Plug, 2-pack
The chart leader by a distance, and the one most people end up with. Two plugs for £20.99 covers the usual pairing of a tumble dryer and a dehumidifier, or a fridge and a freezer, and TP-Link’s app will take your unit rate and turn the kWh into pounds for you. Setup needs no hub and the body is small enough to leave the socket next to it usable, which is more than several rivals manage.
The catch: this listing cannot agree with itself on how much it can carry. The Amazon spec table says 2,860W at 220V, the description on the same page says 2,990W, and TP-Link’s own site says 2,990W. Go with 2,990W. It also works out dearer per socket than buying two singles at today’s prices.
Tapo P110 Smart Plug, single
Identical hardware to the two-pack above at £9.00, which makes it the cheapest plug on this page that actually measures anything. If you have one appliance you are suspicious about, this is the sensible purchase: buy one, leave it on the suspect for a fortnight, then move it to the next one. TP-Link states the spec properly at 2,990W and 13A, and the figures on its product page match its listing.
The catch: one plug measures one socket, so building a picture of the whole house this way takes months of shuffling it around. TP-Link also tells you not to use it for EV charging or for motor and compressor appliances rated above 1/6 HP, which rules out some of the things you most want to meter.
Tapo TP11 Smart Plug, 4-pack
Number two in the chart, and the one to buy if you want to stop guessing and meter four things in parallel over the same winter week. That is the only way to get a fair comparison, because a cold snap that lands while the dehumidifier is metered and the heater is not will flatter the heater. TP-Link gives the TP11 the same 2,990W and 13A rating as the P110 in a smaller body.
The catch: £11.25 a socket is the most expensive per-plug price on this page, and four plugs left on all year carry the standby cost worked out earlier on this page. Worth it if you act on what you find, wasteful if the app goes unopened after a fortnight.
ANTELA Smart Plug with Energy Monitoring, 4-pack
Four monitoring plugs for £29.99 works out at £7.50 a socket, which undercuts everything else here including the single Tapo. It runs on the Smart Life app rather than a manufacturer-specific one, so it sits alongside other Tuya-based kit if you already have some, and it does Alexa and Google Home.
The catch: the listing’s own spec table is incoherent. It gives a 13A current rating, an operating voltage of 220V and a wattage of 3,680W, and those three numbers cannot all be true. 13A at 220V is 2,860W; 3,680W is what you get from 16A at 230V. Treat it as a 13A plug and keep it under 2,990W, whatever the headline figure says.
SONOFF S60ZBTPG Smart Plug
The one for people who have moved off wi-fi for their smart home. It speaks Zigbee 3.0, acts as a repeater so it strengthens the mesh rather than loading your router, and SONOFF publishes a proper spec sheet with the input rating, the maximum load and the casing material on it, which is more transparency than most of this field offers. At £12.77 for one plug it is mid-priced.
The catch: it needs a Zigbee gateway, so the true cost is higher than the sticker unless you own one already, and SONOFF warns that timers stop working if the plug loses the gateway. Its 3,250W maximum load is 13A measured at 250V, the very top of the legal range, so the number to work to in a normal house is still about 2,990W.
Amazon Basics Single Outlet Indoor Wi-Fi Smart Plug
Included here as the control, because it is the one plug in the chart that does not measure anything. For turning a lamp or a Christmas tree on at sunset through the Alexa app it is perfectly good, it needs no hub, and the setup is about as painless as this category gets.
The catch: at £9.99 it costs more than the Tapo P110 single at £9.00, which does everything this does and reports your consumption as well. Its listing works with Alexa only, and its spec table gives a voltage with no current rating or maximum load at all. If you came to this page to find out what an appliance costs to run, this is the one to skip.
Questions people ask
Can I put a 3kW fan heater on a smart plug?
A heater sold as 3kW is right on the edge. At the declared 230V supply a 13A plug passes 2,990W, so a true 3,000W load is already over the line, and most of these plugs are 13A. Heaters also tend to be the appliance people leave running longest, which is the worst case for a connector running at its limit. If the heater’s plate says 3kW, measure it with something rated above it or leave it in the wall socket.
Why does my smart plug disagree with my smart meter?
Partly because they are measuring different things, since the plug sees one socket and the meter sees the house. Partly because only one of them is regulated. Meters used for billing fall under the Measuring Instruments Regulations 2016 and have to meet an accuracy class; a plug-in monitor has no such requirement and none of the six listings we read quotes an accuracy figure. Where the two disagree, the meter is the one that decides your bill.
Does leaving smart plugs plugged in waste money?
A little, and far less than most people assume. SONOFF puts the standby draw of its S60 series at below 1W, and on that basis a plug left on for a full year uses 8.76 kWh, costing £2.31 at the current cap rate. The arithmetic only turns against you if you buy a lot of them and never act on what they tell you.
Can I use one on a fridge or a freezer?
Check the manufacturer’s motor limit first. TP-Link’s P110 page says to avoid appliances with a motor or compressor rated above 1/6 HP and names air conditioners as the example. Compressors also draw a surge at start-up well above their running figure, so a plug sized to the running watts can still be undersized. There is a second risk worth naming: a smart plug that drops offline or gets switched by a routine defrosts your freezer.
Is a smart plug better than the in-home display that came with my smart meter?
They answer different questions. The display tells you what the whole house is drawing right now, from a regulated meter, and costs nothing because you already have it. A smart plug tells you which specific appliance is responsible, which the display cannot. Start with the display you own, and buy a plug when you have narrowed it to a suspect. We compared the free options in our energy monitors guide, and our running cost head-to-heads work through the appliance pairings people ask about most.
Sources
- The Electricity Safety, Quality and Continuity Regulations 2002, regulation 27, declaration of phases, frequency and voltage
- The Measuring Instruments Regulations 2016, regulation 3, interpretation and application
- The Measuring Instruments Regulations 2016, Schedule 1, regulated measuring instruments
- TP-Link UK, Tapo P110 product page and specifications
- TP-Link UK, TP11 product page and specifications
- SONOFF, iPlug Zigbee Smart Plug S60 series specifications and FAQ
Prices, stock and listing specifications were read on Amazon UK on 9 October 2026 and will have moved since. Running costs use the Ofgem price cap unit rate for 1 October to 31 December 2026, direct debit average for England, Scotland and Wales. Look Into earns a commission on some of the links on this page, at no cost to you, and that commission plays no part in which products we include or what we say about them.