kWh: What is a Kilowatt-Hour?

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Last updated: 14 July 2021

Understanding kilowatt hours can save you money on your energy bills and help you to bag the best deal. As a result, you’ll also lower your overall emissions. We’ve put all you need to know about kilowatt hours in this nifty guide.

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Kilowatts (kW) versus Kilowatt-Hours (kWh) – What’s the difference?

It’s important to know the difference between kilowatts and kilowatt-hours, kW and kWh.

A kilowatt, or kW, is a unit of power. Specifically, 1 kW equals 1,000 watts.
A kilowatt-hour (kWh) is a measure of energy: 1 kWh is equal to 1,000 watts (or 1 kW) of energy being used over the course of one hour.

As an example, a 2,000 watt appliance would use 1kWh in just half an hour; or a 500 watt appliance could be running for two hours before it uses 1kWh of energy.

So, a kilowatt is how much power something needs to run, and this will vary across appliances; a kilowatt-hour is how much energy it uses while running, which is the kilowatt unit respective to time.

What will the kWh figure on my utility bill depend on?

Fewer kilowatt-hours on your bill equals a lower energy cost, so the more you can reduce this the more money you save.

Most commonly, it’ll depend on:

The size of the household – Size, both in terms of occupants and rooms, will play a big role in how much energy your home uses. Generally, more people equals more appliances, devices and rooms, which all require additional use of electricity and gas.
Whether your home is energy-efficient - Older homes with single glazing, large windows, or fireplaces, often have a lower EPC rating, meaning it’s likely your energy usage will be greater.
The rate per kWh offered by your energy provider.

Using kWh to monitor energy usage

Once you understand how much a kilowatt-hour is and how they work, it becomes simpler to lower your energy consumption and save money on your bills. A good place to start is by looking at national averages for households of a similar size and structure to yours, and see whether you are over-using (or overpaying!) on your energy bill.

If you do this, be sure to work out an average kWh figure over a period of time; usage can vary hugely with the seasons as people consume more energy in the winter months.

At the end of the year, energy companies may well have undercharged or overcharged you based on your usage throughout the year, so when you look to compare energy suppliers don’t be tempted to grossly underestimate your kWh figure just to get a cheap deal on your energy bill; you may well end up balancing the books in the end.

Where you will find kWh on your energy bill

When reading your energy bill, your kwh usage will be identified with a letter next to it, which helps to determine the accuracy of the figure listed:

the actual (A) amount – which is determined by the company;
the customer (C) amount – whether you have supplied to the company, usually given by metre readings
or an estimated (E) amount. Be aware that if you have an (E) on by your kwh figure then it’s likely your annual bill will fluctuate dependent on how accurate your estimations are.

Therefore, to maximise opportunity to get a better energy deal, it’s recommended you supply meter readings to your energy providers.

Compare energy deals with kWh figures

Understanding kWh can save you a lot of money when it comes to energy usage. Not only will it help you to reduce the amount of energy your home uses, but if you’re looking to switch providers then you may be able to access better bargains by having that accurate information to hand.

When you compare energy suppliers, you will be provided with their cost per kWh. If you want to get the best deal on your home energy, it is a good idea to use this figure to compare energy prices between suppliers.

The energy industry is a booming market, which is good news for consumers. With providers competing for customers there are heaps of energy deals to take advantage of. It might be worth seeing whether switching providers could save you money, or speak with your current provider to see if they can cut you a better rate.

How can I reduce my energy usage?

Knowing how kilowatt hours work is the first step towards making your home more energy-efficient. Here are a few of our favourite ways to reduce the number of kWh you use over the course of days, weeks or years.

Always turn electronics off at the mains – never leave them on standby! We know we sound like everyone’s parents ever, but leaving devices on standby still uses energy. So, a 250 watt television left on standby for four hours will still use 1kWh of energy, which will be included in your bill.
Don’t use more than you need. Only boil as much water as you need for that cup of tea! Use small gas rings on the hob for small pans, or use the warmth of the oven to warm the house after you’ve cooked.
For longer-term investments, look to better insulate your home or replace old white goods or boilers with newer, more energy-efficient models. Appliances have become vastly more economical even within the last decade, so don’t get left behind.

Now that you’ve reduced and better understood your household energy consumption, you’re in a much stronger position to snap up a bargain when choosing a new energy deal.

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Author: Harry Pererra

Harry turns on his experience in web design and programming to write about the latest news in the world of tech and broadband. When he isn’t writing for usave he is working towards his Blue Belt in Brazilian Jiu Jitsu, and prefers dogs to cats.