How much does it cost to boil a kettle? And how to make it cheaper

We all know heating less water reduces the cost of boiling your kettle. Yet, according to research from the UK Tea and Infusions Association, fewer than one in five of us are remembering to only heat what we need.

Overfilling may not be costing you a life-changing amount of money. But since rising food costs mean your cuppa is already more expensive, following some basic kettle etiquette could still boost your bank account. We break down how much it costs to boil a kettle, and how you can make savings.

How much does a kettle cost to boil?

It’s down to power and price per kWh

Even if maths isn’t your strong point, the sums involved in working out the cost of boiling your kettle are relatively simple. It’s all down to the cost per kilowatt unit of energy, the size of your kettle’s element (again based on kilowatts) and how long it takes to boil.

To get an average cost we can use the following information:

• Ofgem’s 30.1p per kWh price cap on electricity *
• A typical kettle has a 3kW element and a 1.7 litre (57 fl oz) capacity**
• A four-minute boil time for a full kettle

Therefore: 90.3 (price per 1kW hour x 3) divided by 60 (to get cost per minute) = 0.015 pence per minute 0.015 pence x 4 (minutes taken to boil full kettle) = 6p cost to boil at full capacity.

*These prices are based on the current price in place until September 30 2023. From October 1 2023, the price per 1kW hour will reduce to 27.35p per 1kW hour
** This is the most common power rating and capacity of kettles sold on the John Lewis website in August 2023.

If you just boiled the amount you needed, what could you save?

Boiling a cupful versus a full kettle

An average cup holds around 235ml (8fl oz) of water. A 3kW kettle will boil this amount of water in around 45 seconds. Therefore, only boiling the amount you need could reduce that 6p to 1.1p.

While we’re only talking pence per cup, if your household consumes around five hot drinks per day, but you fully fill the kettle each time, that’s going to cost you 30p a day and £109.50 per year.

Only boil the amount you need, and it reduces to £20.08 a year. A saving that could pay towards a new kettle, should yours break.

To get an accurate sum for boiling one cup follow these steps:

1. Fill your preferred drinking vessel with water and pour into your empty kettle.
2. Boil the kettle and note how long it takes.
3. Check your electricity or gas bill (if you use a hob kettle) for the price you pay per kWh.
4. Divide the kWh number by 60 to get a price per minute, then divide by 60 again to get a price per second.
5. Multiply this cost by the number of kW of your kettle (for example, three if you have a 3kW kettle).
6. Multiply this cost (either per minute or per second) by the time it took for your kettle to boil.
7. This is the cost for boiling one cup of water.

Ways to reduce the cost of boiling a kettle

Try these tips for a more efficient appliance

1. Cleaning is key

Nothing tastes better than a freshly brewed tea or coffee, and nothing boils quicker than a kettle that’s free of limescale on the inside.

If you live in a hard water area and struggle with limescale, knowing how to descale a kettle is essential – not only for improving taste, but also for reducing the time it takes to boil your kettle. Allow the limescale to build up and the electricity or gas will have to work harder to heat the water.

Limescale can also have longer-term cost implications, says Nigel Bearman, CEO of cleaning company Daily Poppins. “It poses a greater problem as it corrodes the components and shortens the lifespan,” he explains. So, as well as costing more to boil, you could find yourself replacing your kettle more often than normal.

2. Consider a water softener or filter

In response to our article on descaling a kettle, I received a great suggestion from one of our readers who noted that after he and his wife realised they lived in a hard water area, they had decided to only use filtered water in their kettle. The result? Twenty five years on and they haven’t once had to descale. It seems our reader isn’t alone in his suggestion as it’s also advice shared by the experts.

Lydia Mallinson, content marketing manager at Zwilling, tells Saga: “Investing in a water softener will benefit your washing machine and dishwasher, too. They work by removing minerals from your water supply, in turn reducing the amount of limescale in your home.”

But, if you don’t want one or can’t get one fitted, Mallinson confirms that, “another top trick is to fill the kettle from a filtered water jug instead of straight from the tap. This is a quick and easy solution to keeping limescale at bay.”

Less limescale = less energy = less cost.

3. Pick a kettle that has good water indicators

If pouring water from your mug into the kettle each time you fancy a brew seems a little arduous, make sure your kettle is clever as well as stylish. Opting for one with added extras may cost a little more but can save money in the long run.

Debbie Main-McIvor, marketing manager at Dualit, tells Saga about the value in having easy sight of the volume of water you’re adding to your kettle. She recommends purchasing a kettle that has “two measuring windows with cup level and litre indicators, to help you to boil only the amount of water required, from one cup to 1.7 litres [57 fl oz].”

“Invest in a kettle that helps avoid limescale deposits,” is extra advice from Mallinson, who says that consumers should look for ones that have integrated limescale filters.

To minimise energy use, she also recommends we choose a kettle with pre-set programmes for different drinks and a dual-wall heat-insulated body.

Some kettles, such as this one from Zwilling, also include a keep-warm function, which means if you have inadvertently over-filled, the water will remain at temperature for up to 30 minutes, giving you the chance to enjoy another speedy drink or use the excess water for cooking or cleaning.

Although these kettles may come at a higher cost than more standard models, the extra features and temperature control options will save on energy use and money in the long run.