What is a kWh and how much does electricity cost per kWh?
13 May 2024 | OVO Energy
This guide is intended to provide general guidance only. It is not intended to give you advice on your personal financial circumstances. You should seek independent professional advice if you’re unsure about anything mentioned in this guide or what choices to make. Also, the figures included in this article were correct at the time of publication, May 2024, but may now be incorrect due to the changes in the cost of energy.
When you look at prices for energy plans and tariffs or your energy bills, you’ll see electricity and gas measured in kWh - also known as kilowatt hours. Understanding kilowatt hours is a big part of making sense of you energy use.
If you know what a kilowatt hour is and how much it costs, it’s much easier to understand:
How your energy supplier works out your bills
Why some appliances use much more gas or electricity than others
How much individual appliances use
It’s also a good way to make sure you’re getting a fair deal if you’re thinking of switching gas or electricity supplier. By looking at the exact cost of electricity or gas per kWh, you can compare different tariffs like for like.
What exactly is a kilowatt hour or kWh?
A kilowatt hour is a unit of measurement. 1 kilowatt hour is the amount of energy you’d use if you kept a 1,000 watt appliance running for an hour.
Different appliances use different amounts of energy – for exmaple, an alarm clock uses a lot less power than an electric kettle. Here are a few more rough examples:
A 50 watt alarm clock could take 20 hours to use 1 kWh
A 100 watt light bulb could take 10 hours to reach 1 kWh
A 2,000 watt dishwasher could use 1 kWh in half an hour
So what can 1 kWh power?
It varies a lot between appliances. Some are more energy-efficient than others. Here are some estimated examples of what might use 1 kWh:
Keeping an immersion heater (3,000 watts) on for 20 minutes
Cooking in an oven (2,000 watts) for 30 minutes
Using an iron (1,000 watts) for 60 minutes
Running a dishwasher (1,000-1,500 watts) for less than an hour
Keeping a fridge-freezer (200-400 watts) on for about three hours
Watching a 42” LED TV (80 watts) for 12 and a half hours
Keeping an electric blanket (130-200 watts) on all night
Using a laptop (20-50 watts) all day
Keeping a broadband router (7-10 watts) on for five days
What’s the difference between a kW and a kWh?
kW stands for kilowatt and it’s the same as 1,000 watts. It’s a measure of how much power an appliance needs to run. For example, a 1,000 watt vacuum cleaner is also a 1 kW vacuum cleaner.
A kWh stands for kilowatt hour. It’s how you measure energy use. 1 kWh is the amount of energy it takes to run a 1,000 watt appliance for an hour.
How much does 1 kWh of electricity cost?
The price of energy depends on the market conditions and price cap at any given time. Let’s say that the price for 1 kWh of standard rate electricity is 28p and you have a 1,000 watt electric heater.
Here's how to work out the kWh cost of running that heater for 3 hours a day. You would multiply the kW rating of the appliance by the hours it's running and by the electricity cost.
For this electric heater, that would look like:
1kW x 3 hours x 0.28p electricity cost per kWh = £0.84p a day
All of your appliances use energy in this same way. You’ll use some of them for just a few minutes a day, like your kettle, while others are on 24/7, like your fridge.
What determines my electricity cost per kWh on my energy bill?
When it comes to your bill, the price you pay is based on:
Your supplier
Whether you’re on a fixed-rate or variable plan
The type of meter you have
Your region
All these factors could affect your unit rate. That’s the amount you’re charged per kWh of energy you use. If you’re on a fixed rate plan, this will be the same for the length of your contract. If you’re on a variable plan, this price could go up or down.
There’s also the standing charge. This is a fee charged every day, no matter how much energy your home uses. It’s used to pay for things like meter maintenance and the costs involved in providing your property with energy. It’s a bit like line rental for broadband.
Whenever you’re looking at an energy plan, make sure you check both the unit rate and the standing charge to get a clear picture of how much it’ll cost overall. This is much easier if you also have a rough idea of your average energy use.
Energy suppliers base their prices on the cost of wholesale energy. As an energy supplier, we buy wholesale energy, which we then sell to our customers. The price per kWh of that wholesale energy is based on lots of different factors.
How many kilowatt hours does a home use each year?
How many kWh you’ll use annually depends on the size of your home, the number of people in your home, and whether you spend a lot of time there.
According to energy industry figures:
If you live alone in a small home and are out at work full time, you might use 2,000 kWh of electricity a year and 9,000 kWh of gas
A small family who live in a 3-bedroom house and are in full-time work and education might use 3,200 kWh of electricity and 13,500 kWh of gas
4 or 5 students who spend most of the day at home in a large 4-bedroom house could use about 4,900 kWh of electricity and 19,000 kWh of gas
You can find out more in our blog post about average electricity use in the UK.
Can I use kWh to compare energy suppliers?
Yes, you can. If you’re checking energy prices on a comparison site, you can get a much more accurate idea of how much you’ll pay by entering your energy use in kWh. You’ll find it on your bills or annual statement.
Don’t forget to check you’re entering the right time period. Some sites will look at cost over a month, while others will look at cost over a whole year.
Take control of your energy use with a smart meter
By allowing you to see your energy use in real time, smart meters can help you make small changes - saving energy and money. It’s a win-win.
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Looking for more advice? Check out our Energy Experts service for energy efficiency advice that’s tailored for your home.