Which Appliances Actually Cost You Money

There’s a category of energy advice that feels responsible and achieves almost nothing. Unplug your phone charger. Switch the TV off at the wall. Don’t leave the laptop on standby.

None of it is wrong. All of it is rounding error.

The arithmetic

cost = (watts ÷ 1000) × hours × price per kWh

A kilowatt-hour is one kilowatt drawn for one hour. A 2000 W heater uses 2 kWh per hour of running. At 25p per kWh that’s 50p an hour, £1.50 for three hours a day, about £548 a year.

Now the phone charger: roughly 5 W, two hours a day. That’s 3.65 kWh a year. 91p.

Six hundred times the difference. This is the whole story.

Where it actually goes

The rule is simple and almost never stated: anything that makes heat costs real money. Anything that runs electronics doesn’t.

Appliance	Power	Roughly per year*
Immersion heater, 1.5 h/day	3000 W	£410
Oven, 1 h/day	2100 W	£190
Electric heater, 3 h/day in winter	2000 W	£135
Tumble dryer, 4 loads/week	2500 W	£130
Desktop PC, 6 h/day	200 W	£110
Fridge-freezer, always on	~150 W cycling	£70–100
Kettle, 5 boils/day	3000 W	£55
Television, 4 h/day	100 W	£37
Router, always on	10 W	£22
LED bulb, 5 h/day	9 W	£4
Phone charging, daily	~5 W	£1

*At 25p per kWh. Scale proportionally for your own rate.

Look at the top four. Heating water, heating an oven, heating a room, heating wet clothes. Every one is a resistive heating element, and every one dwarfs the entire bottom half of the table combined.

Standby, properly quantified

Since it comes up every time: a device drawing 1 W constantly costs about £2.19 a year at 25p per kWh.

A generous estimate for a whole house, TV, set-top box, microwave clock, games console, several chargers, a soundbar. Might be 15 W of permanent standby. That’s £33 a year.

Real money. Also less than running your tumble dryer three extra times a month.

Do it if it’s easy. Just don’t mistake it for having addressed your bill.

The bit your bill has that this doesn’t

Two things:

Standing charge. A fixed daily fee whether you use anything or not, commonly 50–60p a day, which is around £200 a year before you switch anything on. You cannot reduce it by using less.

Time-of-use rates. On an off-peak tariff the same appliance costs very different amounts depending on when it runs. That’s the actual argument for running the dishwasher overnight. Not that it uses less, but that the same kWh is cheaper.

So the electricity cost calculator gives you the marginal cost: what you save by using something less. That’s the number that answers a decision. The total on your bill doesn’t.

Finding the wattage

It’s on a rating plate, usually the back or underside, or inside the door on ovens and washing machines.

If it only lists amps and volts, multiply: 10 A at 230 V is 2300 W.

One caveat. Thermostatic appliances cycle. A fridge rated at 150 W isn’t drawing 150 W continuously; the compressor runs maybe a third of the time. For fridges, freezers and air conditioners, the annual kWh figure on the energy label is much more accurate than anything calculated from the plate.

What to actually do

In order of how much it’s worth:

1. Heating and cooling. One degree on the thermostat beats every gadget in the house combined. This isn’t close.
2. Hot water. Shorter showers, and don’t heat a full tank you won’t use.
3. Tumble drying. The most expensive routine appliance most households own. A clothes airer costs nothing and runs on air.
4. Fill the machine. A half-empty dishwasher costs the same as a full one, so you’re paying twice per plate.
5. Boil what you need. Filling a kettle for one cup wastes most of the energy in heating water you pour away.
6. Shift to off-peak if your tariff has one.

None of these involve unplugging anything.

The point

Energy advice tends to optimise for what feels virtuous rather than what’s measurable. Unplugging a charger is visible, immediate and free, which makes it satisfying. Taking ten minutes off the tumble dryer is invisible and saves ten times more.

Run the numbers on the three or four appliances in your house that make heat. That’s your bill. Everything else is noise.