What Does It Cost to Run? An Autumn Guide to Heating and Household Appliances

Published 6th November, 2026

Running cost depends on how much electricity an appliance uses, how long it runs and the unit rate on your tariff.

Understanding watts, kilowatts and kilowatt hours makes it easier to estimate costs for your own home.

Check your own appliance and energy bill rather than relying on “cost per hour” figures that can quickly become out of date.

As autumn arrives, heating goes back on, tumble dryers are used more often and appliances such as dehumidifiers or heated blankets may become part of the daily routine.

You may see claims that an appliance “costs 50p an hour” or a heater “costs £3 a day,” but electricity prices, appliance sizes and usage vary. Learning the calculation means you can estimate the cost using your own figures.

How to calculate appliance running costs

What do watts, kilowatts and kWh mean?

Watts (W) and kilowatts (kW) tell you an appliance’s power. There are 1,000 watts in one kilowatt, so a 2,000W electric heater is 2kW.

A kilowatt hour (kWh) measures energy used. If a 2kW heater ran at full power for one hour, it would use 2kWh.

Your energy bill shows a unit rate, usually a price per kWh. Citizens Advice explains that an energy tariff includes the rate you pay for the energy you use and a separate daily standing charge.

Here's how to calculate it in three simple steps.

Appliance power in kW × hours used × electricity unit rate = running cost

Step 1: find out how much power your appliance uses

Start by checking the appliance's power rating, which is usually shown in watts (W) or kilowatts (kW).

If it's shown in watts, simply divide by 1,000 to convert it into kilowatts.

For example, a 2,000W electric heater uses 2kW of power.

Step 2: calculate how much electricity it uses

Next, multiply the appliance's power in kilowatts (kW) by the number of hours you use it for. This gives you the amount of electricity used in kilowatt-hours (kWh).

Let's say you use your 2kW electric heater for two hours:

2kW × 2 hours = 4kWh

That means your heater uses 4 units of electricity over those two hours, assuming it runs at full power throughout.

Step 3: work out how much it costs

Now you know how much electricity you've used, you can calculate the cost.

Find your electricity unit rate on your energy bill. This tells you how much you pay for each kWh of electricity.

For example, if your electricity costs 25p per kWh:

4kWh × 25p = 100p (£1.00)

So, running your 2kW heater for two hours would cost £1.00.

Remember the 25p unit rate is just an example. Use the rate shown on your own electricity bill for a more accurate estimate. If you're on a tariff where electricity prices change throughout the day, use the rate that applies when you're using the appliance.

Running costs for common autumn appliances

Electric heater: Find the wattage on the heater or in its manual, convert it to kW and multiply by the hours used.

Heated blanket: A 100W blanket is 0.1kW. Four hours at full power would equal 0.4kWh before multiplying by your unit rate.

Dehumidifier: Check the rated wattage and running time. Models with a humidistat may switch on and off automatically, so actual use can be lower than a simple full-power estimate.

Tumble dryer and washing machine: These operate in cycles and do not necessarily draw maximum power throughout. If the energy label or manufacturer gives consumption per cycle in kWh, that can provide a more useful figure.

Oven and air fryer: Heating elements switch on and off as the appliance reaches temperature, so rated wattage gives a starting point rather than an exact figure. Cooking time, temperature and the appliance itself all affect use.

Why can the real cost be different?

An appliance labelled 2kW does not always continuously use 2kW. Thermostats, heating elements, motors and programme stages can change consumption while it operates.

Treat calculations based on maximum wattage as estimates. Where an appliance provides a kWh-per-cycle figure, this may give a better basis for comparing particular programmes.

Remember that your electricity standing charge is separate. You pay this daily charge regardless of whether you use a particular appliance.

Use the numbers to make practical choices

Autumn is a useful time to review appliances you are beginning to use more often. You could compare washing or drying programmes, check how long a portable heater is running or review whether a dehumidifier needs to operate for as long as it does.

The aim is not to stop using appliances you need. Understanding their running costs can help you identify wasted energy and make informed choices while keeping your home comfortable.

Get help from LEAP

LEAP’s free Running Cost Guide explains how to work out the energy used by household appliances, alongside many energy-bill and smart-meter guides.

If you are unsure where to find your unit rate, how to read your bill or where your energy is going, Applying for LEAP’s free energy advice service can help you understand your usage and find practical ways to manage costs this autumn.