The 4 Best Mug Warmers of 2025

When the Ember Mug first hit the scene — at the height of the let’s-make-everything-“smart” craze — it took a lot of, er, heat in the press. A coffee mug with a battery that you have to control with your phone? With to-the-degree temp control? Really?

But it turned out that owners truly liked the thing — as does noted coffee guru James Hoffmann. And since then it has caught on to the extent that even Costco stocked it at one point.

The Ember Mug 2 has remained on this list since we first tested mug warmers in 2021, even though the price tag still makes us cringe.

It keeps your drink at a consistent temperature. For around $150 (at this writing), it had better. But during our testing we were impressed to find that it kept our beverage within 1 Fahrenheit degree, plus or minus, from the set temperature. If you want to maintain the optimal drinking temperature for your coffee, the Ember Mug 2 allows you to get it right down to the degree.

“I think maintaining drinking temp, rather than serving temp, is the way to go,” said Hoffmann. “Thermoses work well but tend to hold the coffee hotter. I haven’t tried anything else comparable to the Ember.” In a brand-concealed taste test, Hoffmann even found that keeping coffee hot with the Ember Mug yielded less harshness and bitterness than other, traditional methods of reheating.

In a previous round of testing, we found that it maintained its temperature even through a brisk dog walk in 40 °F weather. It was also one of the few mugs that could warm a room-temperature drink up to the ideal drinking temp, in about 20 minutes.

It has the longest battery life of any self-heating mug we tested. Clocking in at 2 hours, the Ember Mug 2’s battery life was much longer than that of the Nextmug (just over 1 hour 30 minutes) and the Thermacup (around 1 hour 20 minutes).

Lids for the Ember Mug 2 are sold separately, for about $15 (at this writing), but they may be worth the expense since they help insulate your drink while the mug is running, and they also keep it warmer for longer after the battery has been fully depleted. (This is, of course, the case for all mugs, smart or not, and a plate over a ceramic mug achieves the same effect.)

It has plenty of volume. Battery-in-the-bottom mugs all have the same flaw: The battery takes up significant drink space in the cup. It’s almost like a false-bottom drawer — the mug looks deeper from the outside than it is on the inside. The Ember Mug 2 was the least offensive of the bunch in this regard, with a volume that seemed to come closest to matching the mug’s visual appearance.

That said, we tested the 14-ounce mug, not the 10-ounce version. Since 14 ounces is about the size of a normal mug, we suspect that the capacity helps alleviate the feeling of coming up short on your drink. With the 10-ounce mug, you might feel shortchanged.

It looks good and feels fancy. Some of the mug warmers we tested were real uggos. Though we wouldn’t go so far as to say that this mug is cute, the metallic edition of the Ember Mug 2 that we tested looked sleek on desks and end tables, and the charging dock was unobtrusive, just big enough to hold the mug.

The Ember Mug 2 comes in mostly neutral shades that blend in nicely with any decor, though there are some standouts, including candy-apple red. Ember also drops new shades from time to time; powder blue and lavender are new additions at this writing.

Drinking from the Ember Mug 2 feels a little luxurious, too. Maybe there’s a bit of confirmation bias going on because of the steep price tag, but we found it weighty and well balanced, and the handle is a comfortable size.

The app allows for exact temperature settings. The Ember Mug 2 pairs to your smartphone via Bluetooth, and its app makes changing the temperature of your drink as easy as sliding left or right on the main screen. Pairing our phone was easy and took only a minute (if that).

The app makes it very clear when the mug is turned off, displaying a gray screen instead of its usual yellow-to-red range of hues. If you try to set the temperature with the mug off or empty, the slider snaps back to “off” after a few seconds.

The app has preset temperatures for common drinks such as lattes, drip coffee, black and green tea, and cappuccinos. You can also save custom presets anywhere between 120 °F and 145 °F. It has a tea timer, which is nice for people (like me) who forget they have tea steeping and ultimately over-steep. And at the very bottom of a secondary menu, there’s even a card with a handful of recipes. When your phone’s battery is dead, or you’ve turned it off, you can still use the Ember Mug 2 — it just defaults to 135 °F.

We’ve seen reviews detailing issues with the latest version of the Android app, including from some owners who say that they have to continually re-pair their mug with the app or are unable to make custom presets. Our Android tester (who uses a Google Pixel 9 Pro) did not encounter any of those issues, but we did have to factory-reset the mug before it would pair with her phone.

It has commonsense safety features. When the Ember Mug 2 is empty, it does not heat up. You can run the slider up and down all you want, but the mug stays in “sleep mode” until you add liquid.

After standing two hours untouched, the mug shuts off, even if liquid remains and even if the mug is docked. Other battery-powered mugs didn’t shut off at all as long as they were docked, slowly causing my tea to evaporate and leaving a sticky tea syrup that was very disconcerting.

Flaws but not dealbreakers

It costs a lot more than most mug warmers. No matter how “smart” the Ember Mug 2 is and how well it works, at the end of the day, a $150 mug is kind of ridiculous. For the right person, it could be money well spent to keep expensive coffee at just the right temperature for as long as possible. Regardless, the Ember Mug 2’s price tag is a stiff barrier to entry. It strikes us as a good gift; you might not buy it for yourself but would be happy if you got it as a present.

You can’t run it through the dishwasher or put it in the microwave. Because of the open connections on its base, putting the Ember Mug 2 in the dishwasher is likely to destroy it. Some owners report that the mug worked fine after a trip through the dishwasher, but we don’t recommend trying that. The Ember Mug 2 is easy to wash by hand, and most of the time you can probably just give it a good rinse and be fine.

Specs:

• Capacity: 14 fluid ounces, 10 fluid ounces
• Safety shutoff: after two hours without movement or if the mug is empty
• Wash instructions: hand-wash only