How to Estimate the Electricity Cost of Any Appliance

Almost every guess people make about what an appliance costs to run is wrong, and wrong in a consistent direction: the things that feel expensive are cheap, and the boring ones nobody thinks about are where the money goes.

What the Electricity Cost Calculator does

Multiplies watts by hours by days, converts to kilowatt-hours and multiplies by your tariff, giving the cost of running one appliance over a period.

The unit that matters is the kilowatt-hour, and the conversion trips people constantly: 100 watts for 10 hours is one kWh, not 100.

Open the Electricity Cost Calculator and follow the settings and checks below.

Typical draws, for comparison

Setting	What it means
LED bulb	8-10 W
Laptop	30-65 W
Desktop PC and monitor	150-400 W under load
Fridge-freezer	100-200 W, but cycling — daily kWh is the useful figure
Electric kettle	2,000-3,000 W, for two minutes
Electric heater	1,500-3,000 W, for hours — this is where bills are made

How to use it

1. Find the wattage on the appliance label or its rating plate.
2. Enter realistic hours per day, not maximum possible hours.
3. Enter your actual price per kWh from a bill — not the number you half-remember.
4. Compare two appliances rather than reading one in isolation. The comparison is what changes behaviour.

Practical advice

Wattage on a label is usually the maximum draw, not the average. A fridge rated at 150 W does not use 150 W continuously — the compressor cycles, so real consumption might be a third of that. A kettle, by contrast, genuinely pulls its full 3,000 W for the whole two minutes. For anything that cycles or has a thermostat, the label overstates the cost, and a plug-in energy monitor is the only way to get the real figure.

Common questions

Where do I find the wattage?

On the rating plate — usually a small label on the back or underneath, sometimes moulded into the plug. If it lists volts and amps instead, multiply them: 230 V at 2 A is 460 W. Laptop and phone chargers state the output on the brick itself, which is closer to actual consumption than most appliance labels.

Why is my bill higher than these numbers suggest?

Because a bill includes a standing charge that applies whatever you use, and often a higher rate for the first block of units each day. This tool works out the marginal cost of running one thing, which is the right number for deciding whether to leave something on, and a smaller number than the bill it contributes to.

Do standby modes matter?

Less than they used to but not nothing. Modern devices draw around 0.5 W on standby, so a device left on all year costs roughly 4 kWh — pennies. Older equipment, set-top boxes and anything with a transformer can pull 10-20 W continuously, which over a year genuinely adds up.

What is a kilowatt-hour?

One thousand watts drawn for one hour, and it is the unit your supplier bills in. A 100 W bulb for ten hours is one kWh; a 2,000 W heater for half an hour is also one kWh. Getting comfortable with that conversion is most of what makes energy costs intuitive rather than mysterious.

Useful next tools

• Unit Converter — Length, mass, temperature, area, volume, speed and data.
• Percentage Calculator — Percent of, is-what-percent, and percentage change.
• 50/30/20 Budget Calculator — Split take-home pay into needs, wants and savings.
• Currency Converter — Live exchange rates from European Central Bank data.
• Time Calculator — Add or subtract hours, minutes and seconds.
• Date Calculator — Days between dates, or add and subtract from a date.

Vootkit provides a browser calculator and educational guidance. Results depend on the values and units you enter, so verify important financial, academic, safety or professional decisions with an appropriate authoritative source.