Appliance running cost calculator

Where to find the wattage

Every appliance has a rating plate — a sticker or moulded panel on the back, the underside, or inside the door. It gives a figure in watts (W) or kilowatts (kW). If it says 1.5kW, that is 1500 watts.

If the plate gives amps and volts instead, multiply them together for watts. A 5A appliance on a 120V supply draws roughly 600 watts.

Your real cost per kilowatt-hour

The rate printed on your tariff is rarely what you actually pay, because standing charges, fees and taxes are spread across whatever you used that month. The honest figure is the total bill divided by the kilowatt-hours on it.

That number is usually higher than the advertised rate, sometimes considerably, and it is the one to enter above.

Rated wattage is not constant draw

Anything that heats or cools cycles on and off rather than drawing full power continuously. A fridge rated at 150 watts does not use 150 watts for 24 hours — it runs in bursts. For appliances like that, enter the hours it is actually running rather than the hours it is switched on, or treat the answer as an upper bound.

Appliances that run flat out while on — kettles, heaters, hair dryers, lighting — are the ones this calculator is most accurate for.

What this does not cover

This is running cost only. It says nothing about whether an appliance is wired correctly, whether a circuit can carry it, or whether anything needs replacing. Those are questions for an electrician looking at the actual installation, and no calculator should answer them.