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Is my kettle almost boiled yet? If that’s a question you find yourself asking every time you’re waiting for a cuppa, the Tefal Smart’n Light Digital Kettle KO853840 is the answer. The kettle will count up by the degree as it heats the water, displaying the information on one side. It also offers multiple temperatures, with one button to scroll through 40ºC, 70ºC, 80ºC, 90ºC and 100ºC options, and another that takes you straight to boiling. Sleek, fascinating to watch and capable of boiling quickly, what more could you want?


  • Variable temperatures
  • Washable limescale filter
  • Drip-free spout


  • Pricey
  • Just two water level marks inside
  • Narrow spout


  • USAunavailable
  • Europeunavailable
  • Canadaunavailable
  • Australiaunavailable


There are many small appliances that include timers as part of their spec, so the obvious question is why we don’t see them on kettles? Tefal’s Smart’n Light Digital Kettle KO853840 comes the closest to including such a feature, in the form of its count-up display, which indicates the temperature of the water as it’s actually heating. So no longer will you need to lurk nearby, listening for the noise of bubbling water, as you’ll be able to see how far you are from your desired temperature.

It’s also fantastically convenient for those who like water at different temperatures – just select from one of four options, go straight to 100ºC, or take it off the base when it hits your ideal 72ºC. With this much precision, you’ll wonder why you ever settled for a single boiling option again.

Design and features

  • Large, clear display that can be seen from several metres
  • Concealed element
  • Removable, washable limescale filter

While kettles that light up can be seen as a gimmick, this isn’t the case with the Tefal Smart’n Light Digital Kettle. It uses its built-in digital screen to relay information: the starting temperature of water in the kettle; the temperature as it rises; the temperature you’ve chosen to heat it to (40ºC, 70ºC, 80ºC, 90ºC and 100ºC options); as well as indication of you having selected the 30-minute keep-warm feature.

Being able to view the current temperature is handy, because it gives an idea of how long is left before the water has reached the desired temperature. It’s a feature that’s missing on the majority of kettles, even the Smeg KLF04, which has a similar selectable range of temperatures.

Tefal Smart'n Light Digital Kettle KO853840 current temperature

The keep-warm function maintains 100ºC boiling water at 95ºC – ideal, if the kettle has boiled while you’re mid another task, or the phone rings. Although this is only an option for 25 seconds once boiling is complete.

In some respects, the Smart’n Light Digital Kettle is an eco-friendly small appliance. The ability to boil water to the exact temperature you want is a smart way to save energy, rather than boiling to 100ºC then waiting for it to cool to a white tea-suitable 70ºC.

However, in other respects, it’s less so – a lack of internal marks for water volume (there’s only a minimum and maximum fill) means either having to measure out water before filling the kettle, or overboiling / repeated boiling. Its minimum fill equates to around 450ml, which is almost two cups’ worth – meaning that if you regularly boil water for one, you’ll be overboiling each time.

Tefal Smart'n Light Digital Kettle KO853840 inside

Inside you’ll find a washable filter, which you can keep from clogging up with regular cleaning, giving you fresh water into your cup.

Tefal Smart'n Light Digital Kettle KO853840 filter

There’s plenty more to like, too – it will remember the last temperature at which you boiled water, so you won’t have to keep selecting 80ºC for a steady stream of green tea, plus the option of 40ºC water is ideal for keen cooks. As well as the temperature option, there’s a button that gives the option to boil straight to 100ºC, so you don’t have to fiddle about when you want boiling water.

Tefal Smart'n Light Digital Kettle KO853840 controls


  • One litre boils in 2mins 20secs
  • Smooth pouring from narrow spout
  • Full kettle boils in 3mins 7secs

The act of filling the Tefal Smart’n Light Digital Kettle KO853840 is straightforward enough – a button on the lid pops the top open – but seeing how much water you’re adding is more difficult. Not only is the lid opening fairly narrow, the minimum and maximum marks inside are indentations rather than printed on, making them difficult to see without some tilting.

The control buttons are located at the top of the handle and unobtrusive – there are just two, one for boiling to 100ºC, and another for scrolling through variable temperatures that doubles as the keep warm when given a long push.

Tefal Smart'n Light Digital Kettle KO853840 pouring hot water

This kettle is relatively fast at heating: one litre boiled in 2mins 20secs, while its maximum of 1.5 litres took 3mins 7secs – and the kettle beeps twice when it’s finished. The spout is narrow, which makes for an even, controlled pour; it’s perfect for decanting water into smaller cups, but more time-consuming for filling pans.

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Should you buy it?

If you often use water at different temperatures (such as for green tea, herbal tea or coffee), like to keep an eye on boiling progress, or want a minimal, modern kettle to grace your worktops, then this is a great choice.

If you’re looking for a more budget kettle, then look elsewhere. Also, there are no cup measurements and limited fill marks inside, so boiling only as much water as you need is tricky.

Final thoughts

The Tefal Smart’n Light Digital Kettle KO853840 is only available in black, which is the one downside of anyone looking for a wider choice to match their kitchen. That said, everything else about this kettle is quality. It boils fast, offers a neat display and a choice of temperatures. If you do want a different design, check out our best kettle guide; if you want a flexible and powerful kettle, this is it.

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Can you select multiple temperatures on the Tefal Smart’n Light Digital Kettle KO853840?

Yes, you can. It has a low 40ºC setting, plus 10ºC increments between 70ºC and 100ºC.

How fast is the Tefal Smart’n Light Digital Kettle KO853840 to boil?

This has a 3kW element, the largest you can get in a kettle, so it boils as fast as is possible.


Size (Dimensions)
Release Date
First Reviewed Date
Model Number
Water capacity
Kettle type
Integrated filter
Multiple temperatures

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