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How to calculate appliance running cost in the UK

Updated: October 2026

The heater label says 2000 W and you want a figure in pence, not a guess at the quarterly bill. This is how to calculate appliance running cost in the UK from kilowatt-hours and your own unit rate. The Ofgem average below is an example you replace. The standing charge is a separate daily line, and a plug on one socket never sees the rest of the house. Our [energy meter comparison](/hub/measuring-equipment/energy-meter) is where the meters live. This page is the arithmetic. Products Compared did not invent a saving, and we did not meter your home.

The heater label says 2000 W and you want a figure in pence, not a guess at the quarterly bill. This is how to calculate appliance running cost in the UK from kilowatt-hours and your own unit rate.

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On this page
  1. 1.The sum in one line
  2. 2.The October 2026 example
  3. 3.What the sum leaves out
  4. 4.When the label is not the load

The sum in one line

Pence equals kilowatt-hours times your unit rate in pence. Kilowatt-hours equal watts divided by 1000, times hours. A true 1000 W load for one hour is 1 kWh. National Energy Action uses the same shape: watts times the unit rate, divided by 1000. On the Tapsin, a review says the cost rolls after 99.99. Trust the kilowatt-hours.

The October 2026 example

Ofgem's Direct Debit average for England, Scotland and Wales from 1 October to 31 December 2026 is 26.32p per kWh and 54.83p a day. That is not your contract and not Northern Ireland. If your bill says 21p, swap 21 for 26.32. At 26.32p only, 1000 W for one hour costs 26.32p. A 2000 W hour costs 52.64p.
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What the sum leaves out

Do not add 54.83p to an appliance hour. The standing charge is for having the supply. Over 31 days the example is about £17 before any unit is used. It is not the cost of the heater. A plug misses every other circuit. Which? limits it to one appliance or one extension. A clamp is a different job. The buying guide is that choice. None of these listings is shown as a meter for billing a lodger. A qualifying purchase can earn a commission at no extra cost to you.

When the label is not the load

A nameplate wattage is a rated figure, not the average hour of a fridge. A 2000 W heater draws that only while the element is on. A KETOTEK review says the timer paused when the thermostat opened. Multiplying 2000 W by 24 hours invents a cost. That is a rule of thumb you have not measured. A 13 A plug at 230 V is about 2,990 W. A printed 3680 W still conflicts with the fuse. The buttons sit on how to use an electricity usage monitor.

Common questions

What is the formula?
Kilowatt-hours equal watts divided by 1000, times hours. Pence equal those kilowatt-hours times your unit rate in pence per kWh. A 1000 W load for one hour is 1 kWh. At a unit rate of 26.32p that hour costs 26.32p, and only if 26.32p is the rate you intended to use. The same sum is what a plug-in cost line does after you type a tariff.
Should I use 26.32p?
Only as a labelled example. It is Ofgem's Direct Debit average for England, Scotland and Wales from 1 October to 31 December 2026. It is not Northern Ireland, and it is not a fixed deal. Replace it with the unit rate on your bill before you decide whether an appliance is expensive. If the bill shows a day rate and a night rate, use the rate for the hours you ran the load.
Does the answer include the standing charge?
No. The example standing charge is 54.83p per day on that same Ofgem Direct Debit average, billed for the supply, not for one appliance. Leave it out of the heater's hour. You still pay it on the bill. Adding it into a one-hour sum makes the appliance look dearer and hides a charge that does not change when you switch the appliance off.
How do I turn watts into kilowatt-hours?
Divide the watts by 1000 and multiply by the hours. 500 W for two hours is 1 kWh. 2000 W for 15 minutes is 0.5 kWh, because 15 minutes is 0.25 hours and 2 kW times 0.25 is 0.5. Then multiply by your unit rate. A thermostat that switches off means those hours are shorter than the time the appliance was switched on at the wall.
Why is the meter's cost different from my bill?
The meter priced one socket at the rate you typed. The bill prices the whole home, adds the standing charge, and uses your supplier's rate, which may not be 26.32p. A wrong unit, pounds instead of pence, makes the gap larger still. On the Tapsin, a UK review says the cost rolls after 99.99, so the money line can also under-read while the kilowatt-hours keep going. Compare kilowatt-hours first.
Is Northern Ireland on this cap?
No. The 26.32p and 54.83p figures are Ofgem's Direct Debit averages for England, Scotland and Wales for 1 October to 31 December 2026. Northern Ireland is outside that cap. Use the unit rate and standing charge on your own bill. The formula, kilowatt-hours times unit rate, still works. The example pence do not travel with you.
My tariff is a fixed deal. Which number do I use?
Use the electricity unit rate on the bill or the contract schedule, in pence per kWh. A fixed deal can sit under or over the cap. The October 2026 example will mis-state every hour if you leave it in the sum. If the bill shows more than one unit rate, pick the rate that applied when the appliance ran, and keep the standing charge as its own daily line.

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Sources

Public UK sources on the price cap, trade meters, notifiable electrical work and competence. Shelf prices, stars and review counts are the amazon.co.uk lines in the twelve listings dated 16 October 2026. Prices move.

  1. Ofgem, energy price cap 1 October to 31 December 2026 (retrieved 16 October 2026)
  2. Ofgem, energy price cap unit rates and standing charges (retrieved 16 October 2026)
  3. GOV.UK, Measuring Instruments Regulations 2016, Great Britain (retrieved 16 October 2026)
  4. Measuring Instruments Regulations 2016, SI 2016/1153 (retrieved 16 October 2026)
  5. GOV.UK, building work, replacements and repairs (retrieved 16 October 2026)
  6. HSE, electrical safety introduction (retrieved 16 October 2026)
  7. Electricity at Work Regulations 1989, regulation 16 (retrieved 16 October 2026)
  8. Which?, energy monitors and measuring power use (retrieved 16 October 2026)