I tested whether it’s cheaper to make a cup of tea with a kettle or microwave – and the results surprised me


WE’RE paying too much to make a cup of tea, experts warned earlier this month.

Price comparison site uSwitch recently tested the cost of making tea using the kettle, gas hob and microwave – and the kettle was found to be dearer than the other two methods.

Experts have warned we’re paying too much to make a cup of tea

Using a covered pan on the gas hob was found to be cheapest, with 100 cups costing 87p to heat up.

But that’s not an option for those without a gas hob.

The microwave worked out cheaper than using a kettle, with 100 cups costing £1.12 to make, as opposed to £1.21.

So are microwaved mugs of water the new solution for a budget brew?

Here reporter Harriet Cooke puts it to the test.

I never think twice about switching the kettle on at least five times a day – but I’m aware it’s one of my kitchen’s biggest fuel guzzlers.

So I decided to see how using a microwave might save my costs.

My no-nonsense Breville kettle – which fires up as soon as you touch it – can heat a mug of water within 50 seconds, meaning in a rush I can have a brew made in under a minute.

According to energy efficiency database sust-it.net, the cost of my kettle’s 50-second water-heating effort is 1.2p.

The microwave test proves much trickier – not least because I’m super-scared of getting third degree burns. 

The internet is full of warnings of the dangers of water super-heating in the microwave, where the liquid is heated to higher than boiling point but is not actually boiling.

If I disturb superheated water it could erupt in a fury of scalding water, apparently.

So I was careful. I added a wooden spoon into my mug of water which apparently prevents superheating.

I then microwaved it on the 1000W setting for 30 seconds, and stopped to tap the mug. It was nowhere near hot enough to make tea.

I blasted it for another 30 seconds, and checked again. After five rounds of this I once again tapped and carefully touched the water… to find it defiantly lukewarm. I was getting bored, and thirsty.

The tea-dious process went on and on. In the end it took 10 rounds of 30-second heating, so five minutes of microwaving in total, before I deemed my water hot enough for tea.

Five minutes of microwave heating on the 1,000W setting currently costs 3.27p – almost three times the cost of using my kettle so I definitely lost out financially.

And there’s a cost in terms of time as well.

The whole process took longer than just cooking – around 11 minutes once I had done all the tentative faffing about to check for superheating. Maybe I’m being overzealous but I didn’t want to risk getting burns.

Another problem is that it’s hard to see when the water’s reached the right temperature, unless you have a thermometer that measures water temperature, which lots of people won’t have.

I judged it ready when I saw the water profusely steaming, but it may have been boiling before that. I’m no physicist. 

Given how long it took, I can’t imagine the bother of heating larger amounts of water in there.

For all the benefits of microwave cooking, while it can save considerable energy on a conventional oven, it’s not a patch on the kettle so far as my tea-making is concerned.

Having said that, I could do more to trim my kettle costs. One positive aspect of using the microwave is heating the exact amount of water needed, whereas I do tend to overfill my kettle.

Here are some handy tips to save on kettle costs.

  • Don’t overfill – pour in the number of cups you need rather than filling the kettle using the tap. This can save as much as £50 a year.
  • Descale the kettle to prevent limescale building up around the element, which causes it to use extra energy. To do this, unplug it and fill it with a mixture of half white vinegar and half water. Leave for an hour then boil, let it cool, rinse it out and boil fresh water in it again.
  • Some kettles tell you how hot the water is, like the Aigostar electric model, currently £34.99 from Amazon. This is useful if you don’t need to get to 100C. Green tea brews low at 70C or 80C.