Smart plugs that show watts and shift off-peak

A smart plug does not make a kettle or a dehumidifier more efficient. It does two smaller jobs. It shows the watts the thing in the socket is using, and it can turn that socket on and off at a time you choose. On a tariff with a cheap window, the second job is how the plug saves money. The first job is how you find out whether anything is worth moving.

The value of one shifted unit

Ofgem’s October–December 2026 electricity average is 26.32p/kWh. Intelligent Octopus Go’s overnight rate is 7.6p/kWh from 23:30 to 05:30. The gap is 18.72p per kWh, call it 18.7p. That is the saving for every unit you move from the cap rate into the off-peak window. It does not matter whether the unit went through a washer, a dehumidifier or a charger, as long as the unit really moved and the rest of the house was not accidentally added.

• 1 kWh shifted: 18.7p.
• 2 kWh shifted, the example on the homepage card: 37.4p.
• A steady 10W for 24 hours is 0.24 kWh. At 26.32p that is 6.3p a day. At 7.6p it is 1.8p. Shifting it, if you can, saves about 4.5p a day. Many always-on loads cannot be shifted because you want them on.

The 10W case is an example so you can read a plug’s display, not a claim about a typical UK home. Write down what the plug shows for an hour, multiply watts by hours, divide by 1,000, and you have kWh. Then multiply by 18.7p if that whole block can move into the cheap window. The homepage timer tab does this for a dishwasher at 1.1 kWh, a washing machine at 0.9 kWh, a heat-pump dryer at 1.4 kWh and a 2.0 kWh immersion-style load. Those four numbers are the calculator’s assumptions. Open the calculator and set the weekly counts you actually run.

What to schedule, and what not to

A dehumidifier on a six-hour laundry mode, or a heated airer rated at 198W, fits a timed socket and fits the six-hour cheap window. Start them at 23:30. The airer’s electricity for those six hours is 1.188 kWh, or 9.0p at 7.6p, as set out in the winter drying guide.

Use the washer and dishwasher delay-end buttons when they have them, so the machine’s own heater runs in the cheap hours and the appliance still ends the cycle the way it was designed to. A plug that cuts power is the wrong tool for a tumble dryer or any load above the plug’s rating, and it is the wrong tool for anything that would be unsafe if it started while you were asleep and a fault developed. Keep the kitchen alarms that you already need. The plug is a timer and a meter, not a reason to leave a risky load unattended.

Four plugs are enough to meter more than one socket and to notice the always-on ones: a set-top box, a second fridge, a console on standby. Turn each off at the plug for a day if you do not need it, and the app’s kWh tally tells you whether the standby was pence or tens of pence. Do not copy a “phantom load” figure from a headline. Read your own sockets.

What this does not change

The 54.83p daily standing charge is about £200.13 a year and does not shrink because a plug moved 2 kWh. Octopus also has to have you on a tariff with a real off-peak window. A flat 26.32p tariff gains nothing from a 23:30 schedule except the convenience of the timer. If you type an off-peak rate that is not below the day rate, the homepage badge on the plug card says the shift needs a cheaper off-peak rate, which is the same point.

No shop price is used. A payback month would need one, and this site has not checked a live price for the 4-pack.

Sources

• Ofgem, price cap 1 October–31 December 2026
• Ofgem, unit rates and standing charges
• Octopus Energy, Intelligent Octopus Go
• Lakeland, Dry:Soon family specifications (Mini, 198W)

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