- With three-fifths of Gen Z (58%) admitting to making tea in the microwave[1], here’s why you shouldn’t try a slow cooker or air fryer to make one either
- A 300W slow cooker could take more than three hours to get the water hot enough to make a cup of tea, but a lot could have evaporated by then
- The gentle heat of the slow cooker also means that it would use 900Wh of energy in that time, 20 times more energy than a kettle[2]
- Using an air fryer isn’t advised at all, as the fan could blow hot water around the device and potentially damage the heating element
- Brits will spend £390 million a year on energy to make nearly 37 billion cups of tea, according to new research for National Tea Day, Tuesday 21 April[3]
- Uswitch.com offers tips to bring your beverage bill down on National Tea Day, including saving energy by not over-filling your kettle.
With a shocking three-fifths of Gen Z (58%) boiling the water for their cup of tea in the microwave[1], households are being warned not to try using other inappropriate appliances for the task this National Tea Day (Tuesday 21 April) by Uswitch.com, the comparison and switching service.
While a slow cooker could theoretically get water to boiling point, the reality is that much of the water would evaporate before getting to a usable temperature.
The gentle heat of the slow cooker also means that it’s a very inefficient method, and could end up using much more energy than the humble kettle.
A 300W slow cooker on high would use 0.9kWh of energy if it took three hours to get the water to temperature – 20 times the amount used by a kettle[2].
Table: Various ways and costs for boiling a cup of water
| Cup of tea (300ml water) | Power (kW) | Time to boil | Energy used (kWh) | Total cost | Total cost for 100 cups of tea (£) |
|---|---|---|---|---|---|
| Gas hob (covered pan) | 1.95 | Three mins 37 secs | 0.118 | 0.67p | £0.67 |
| Gas hob (uncovered pan) | 1.95 | Four mins, five secs | 0.133 | 0.76p | £0.76 |
| Microwave | 0.8 | Three mins | 0.040 | 0.99p | £0.99 |
| Kettle | 3 | 52 secs | 0.043 | 1.07p | £1.07 |
| Electric hob(covered pan) | 1.95 | Three mins 37 secs | 0.118 | 3p | £2.90 |
| Air fryer | 1.4 | 20 mins | 0.467 | 12p | £11.51 |
| Slow cooker | 0.3 | Three hours | 0.900 | 22p | £22.20 |
Source: Uswitch.com
Air fryers heat by using hot air, making it a much less efficient way of heating water, compared with appliances where the heating element has direct contact. The lack of a sealed lid also means that evaporation can allow heat to escape constantly.
Using an air fryer isn’t advised at all, as the fan could blow hot water around the device and potentially damage the heating element.
The cheapest way of heating water for a cup of tea is to use a covered pan on a gas stove, with the method costing less because of the lower cost of gas.
Brits will spend £390 million a year on energy to make nearly 37 billion cups of tea, according to new research for National Tea Day[3].
Gen Z are nearly ten times more likely to use the microwave than the Silent Generation – those aged 79 and older. Meanwhile, Millennials (those aged 28 to 43) are more than twice as likely as Gen X to commit the unforgivable habit[1].
PG Twits: What proportion of each generation make tea in a microwave
| Generation | Ever use a microwave to make tea |
|---|---|
| Gen Z (18-27) | 58% |
| Millennials (28-43) | 32% |
| Gen X (44-59) | 15% |
| Boomers (60-78) | 10% |
| Silent Generation (79+) | 6% |
Source: Uswitch.com
Men are more likely to be microwave users, with nearly three in ten men (28%) microwaving their tea – compared with a fifth (19%) of women[1].
Natalie Mathie, energy expert at Uswitch.com, comments: “It sounds like it goes without saying, but with so many Gen Z people making tea in the microwave, we don’t advise you to try other appliances like slow cookers and air fryers.
“The trusted kettle is the simplest and quickest way to boil water for tea, while heating water in a covered pan on a gas hob is the cheapest option.
“Make sure you keep a lid on pans, as letting the water evaporate as you heat it means it will waste energy and end up costing you more.”
Uswitch’s tips for making the most efficient cup of tea
1. Use a plug-in kettle. These boil water faster than on an electric hob, saving you precious time and pennies.
2. Some eco kettles have a vacuum flask that is claimed to keep water hot for up to four hours — meaning you could enjoy multiple warm drinks with just one boil.
3. Only use as much water as you need for the number of hot drinks you are making. It will take less time for the kettle to reach boiling point, saving you energy.
4. Boiling water on an electric hob is more expensive than using a kettle – but a gas hob might save you money. This is because the price of gas is cheaper than electricity.
5. Make sure you’re not overpaying for your energy by seeing if you can save with a fixed deal. Making a cuppa might be even cheaper if you can lock in lower rates.
Compare energy deals now at Uswitch.com to see if you can switch and save.
For more information
Rianna York | Energy PR Manager
rianna.york@rvu.co.uk
Twitter: @UswitchPR
Notes to editors
1. Research conducted online by Opinium, 6th to 11th June 2025, among 2,002 UK energy bill-payers, weighted to be nationally representative. Respondents were asked ‘How often do you do each of the following? Boil water for tea or coffee in the microwave.’ 24% of respondents said they had done this. 28% of men and 19% said they had done this.
2. See table in release.
3. UK Tea & Infusions Association says 100 million cups of tea are drunk every day. Cost of boiling a 3kWh kettle for 300ml of water = 1.07p. £0.0107 x 100 million = £1,070,000 in energy costs a day. £1.07 million x 365 days a year = £390 million. 100 million cups of tea a day / 47,205,195 adults in the UK = 2.1 cups of tea a day on average. 2.1 cups x 365 days a year = 773 cups of tea a year x £0.0107 per brew = £8.27 yearly cost.