Free UK tool
Is a Smart Plug Worth It? Breakeven Calculator
Smart plugs cost money to buy and draw about half a watt themselves. Enter what your device idles at, what the plug costs, and your electricity rate — this tells you how many months until the plug has paid for itself.
The honest answer is that a smart plug is a brilliant buy for a games console or soundbar and a pointless one for a phone charger. This smart plug payback calculator (breakeven calculator) shows exactly where the line sits for your device, at UK electricity prices, before you spend anything.
Your device
Figures include the plug's own ~0.6 W self-draw. Standby wattages are typical published values, not our bench measurements.
Your verdict
Probably worth it
Payback within a year and a half — fine if you'd use the scheduling and remote control anyway.
6.5 mo
to break even
£18.49
saved per year
£82.47
net gain over 5 years
How the maths works
The saving is the device's standby watts minus the plug's own draw, multiplied by the hours per day the plug keeps it off, multiplied by 365 and your unit rate. A 10 W console cut off for 22 hours a day saves roughly 78 kWh a year — about £19.11 at the rate you've entered — so a £10 plug recovers its cost in well under a year.
Where people go wrong is applying plugs to tiny loads. A 0.3 W phone charger saves less than the plug itself consumes, so the payback is literally never. The rule of thumb: anything idling above 4 W is a candidate, anything below 1.5 W is not.
Common questions
How much electricity does a smart plug use itself?
Typically 0.5–1 W while switched on — about £1–2 a year at UK rates. That is why this calculator subtracts the plug's own draw from your saving before working out payback.
Which devices are worth putting on a smart plug?
Games consoles, soundbars, set-top boxes, coffee machines and printers — anything idling above roughly 4 W. Skip chargers, routers and anything that needs to run or update overnight.
Is it safe to leave a smart plug cutting power every night?
Yes for ordinary consumer electronics, provided the plug is a UK-certified model from a reputable brand. Avoid using smart plugs on heaters, washing machines or anything with a motor or heating element that could start unattended.