Ember Mug Review 2022: I Tested It for a Year

Jun 18, 2023

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How the buzzy heated mug faired in our Lab tests — and daily life.

Back in 2021, I found myself curious about the Ember self-heating mug. While I do drink iced coffee, I'm one of those people who can drink hot coffee year-round. And I do mean hot; I don't want lukewarm coffee. I've never enjoyed coffee reheated in the microwave: I like milk (no sugar), and the milk skin on a reheated coffee is unappealing. Was a heated mug the answer?

So I jumped at the chance to test the Ember Mug 2 in August 2021. I did some cursory tests — you can read more about how I put it through the paces in the Good Housekeeping Institute Kitchen Appliances and Innovation Lab below — and also just used it in my office life. When official testing was done, I kept on using it. So here we are more than a year later, and it's time to share the upsides and downsides of this coffee tech.

Heated mugs keep coffee hot via a hotplate or a built-in heating element. Ember, which falls into the built-in heating element category, is among the best-known. According to the brand, Ember's founder and CEO, Clay Alexander, is an inventor who holds more than 200 patents worldwide. The first generation of the heated Travel Mug launched in 2010, and in 2018, the self-heating mug drew investors like Nick and Joe Jonas.

The company is now on the second generation of the product — the Ember Travel Mug 2 — which has a longer battery life and a new LED touch screen. Ember also offers the 6-ounce Ember Cup (a handleless variation designed for espresso drinks) and the 10- and 14-ounce Mug 2 (a traditional coffee mug with a handle).

Ember's products rely on sensors placed throughout the mug that monitor the temperature of the liquid inside and then turn on built-in heaters if the temperature drops below the preset temperature. Out of the box, the default temperature is 135˚F (57˚C), but you can use the Ember app to set the temperature — in 1˚ increments — you prefer. The range for all the products is 120°F – 145°F (50°C – 62.5°C). The app will also send notifications when the set temperature is reached, but you can choose not to receive any. I share more thoughts on the app below.

✔️ Easy to use: A regular mug is inherently uncomplicated: You fill it; you sip from it. I didn't want an Ember mug to add too much tech to a simple daily task. And I definitely didn't want to feel like I was on my phone when I wanted to be drinking coffee. The good news: Ember felt set-it-and-forget-it to me. I downloaded the app and paired it with my mug — and now, thanks to testing, multiple mugs. It is very easy to load more than one and then switch between them from your home screen of little mug avatars. I set the temperature I wanted to keep my beverages. And that was it: Now I just turn my mug on — i.e. push the large button on the bottom — fill it and sip from it.

✔️ Useful app: I do appreciate that you can go deeper with the app so that it earns its spot on your phone. It offers presets for latte, cappuccino, coffee, black tea and green tea. Milk-based drinks get a gentler heat to help prevent scalding. There's also a tea timer that offers an up-to-10-minute countdown within the app and also suggests steep timers for green, black and herbal teas. The app even includes recipes like "Chai Spiced White Hot Chocolate" and "Beet Latte" if you want to expand your warm beverage repertoire. You can also use the app to choose the LED color that shows up on your Mug 2 and sync it with Apple Health if you want to track caffeine consumption.

✔️ Simple to keep charged: I like that charging is easy. I'm a coaster user, so I'm always putting my mugs down in a specified place anyway. The Ember charging coaster is a simple landing pad that's just permanently charging at my desk. When I pick up the mug, it's fully charged.

✔️ Solid performance: It succeeds in its main objective: It keeps my coffee hot. I use my Ember Mug 2 when I'm at the office, and apparently, I love to get a coffee and settle in ... only to realize I need to do something away from my desk. With the Ember mug, I feel like I've granted myself a grace period because I know my drink will still be hot when I come back to it. Both the Mug 2 and Cup have been tested in our Lab and sent to consumer testers, and both got positive feedback, leading them to earn our 2021 Kitchen Gear Awards and 2022 Coffee Awards, respectively.

One tester of the Mug 2 said, "I was especially impressed that it not only kept my coffee hot, but it also heated up lukewarm leftover coffee by 20 degrees in only five minutes." In my Lab tests, the Mug 2 held the set temperature for nearly its entire battery life, dropping only slightly in the last 15 minutes. In my daily life, I never felt a drop in temperature during regular use. Even better: The mug itself does not overheat, so I have never burned my lips, as I have with some other mugs. The Travel Mug 2 also aced the heat retention tests, but the Cup did come in under the set temperature for much of the 90-minute battery life.

✔️ Comfortable to hold: The circumference of the Cup is grippable for most hands, even though it doesn't have a handle. (I've also found that the 6-oz Cup fits nicely under my espresso machine and helped my espresso shots stay warm.) The Mug 2 gives me a nice, three-finger grip with a spot for my thumb to rest on top for control. And despite the built-in battery, Ember's mugs are not overly heavy. The Cup and Mug 2 have a bit of extra weight for their size, but I have never felt a strain. The Travel Mug 2 feels like a standard travel mug to me.

✔️ Must wash by hand: I'll say right off the bat, it's not dishwasher safe. That's not a dealbreaker for me — in fact, I've found them easy to clean, thanks to a wide opening and slick surfaces — but it is a small con.

✔️ Will affect the taste of your coffee: The other issue, which isn't specific to Ember but applies: All heated mugs will change the flavor of your coffee over time for the worse — similar to the way drip coffee continues to "cook" when it's kept warm on a heating plate. This means the longer your brew is held in the mug, the more likely it is to taste more sour, bitter or metallic — all issues I encountered in my testing across the different Ember mugs, though your specific outcome will depend on the coffee beans you use. When I step away from my mug, it's long enough that I'd notice a decrease in temp if I were using a regular mug, but often only 10 to 15 minutes. And then I finish my coffee in probably 20. So I'm grateful for the heat assist over roughly 30 minutes. But I will say that if you want to use the Ember as some sort of coffee incubator over the full 90-minute battery life, you will notice a difference in the flavor from the fresh cup to the final sip.

✔️ Must purchase lid for Cup and Mug 2: The company offers the Travel Mug 2, so there is a clear option if you want something for your commute; it didn't leak in my tests and kept coffee warm over the battery life. It also has a well-designed push-button lid opening that lets you drink from any angle. But the others are not designed for portability. They're very much intended to take the place of your regular around-the-house (or office) mug. One consumer tester agreed, noting that their experience with the Cup was positive but that they didn't like that they "could only use this cup while sitting at home or in the office." And if you do want a little extra protection from spills, you'll have to purchase a sliding lid (available for the 10- and 14-ounce sizes) separately. I have not yet tested the lids but will be doing so in the coming months.

When I tested the Ember mugs in the Kitchen Appliances and Innovation Lab, I wanted to know whether they really kept the coffee at a consistent temperature. To track the heat over time, I inserted a thermocouple (a thin, wire-like thermometer) into each mug and captured the data during Ember's stated battery life for each.

The other piece of the puzzle was flavor. Would waging war against the laws of thermodynamics — i.e. keeping coffee hot over a two-hour period — make the coffee taste overcooked? To find out, I tasted coffee from a control cup and then from each Ember mug every 30 minutes. I made notes on the aroma, bitterness, acidity, mouth feel and temperature sensation of each cup.

The last issue was ease of use. I read the owner's manual and considered the design of the app. I checked out the type and readability of the controls and assessed the feel of the mug in my hand and the comfort of drinking from it. I decided what I thought about washing each by hand, as none is dishwasher safe. For the travel mug, I also factored in opening and closing the mug and using the touch-control interface. I also tested whether it leaked by putting it through our timed leak tests: tipping it over, rolling it side to side and shaking it upside down.

In a word: Yes. If you think you'd benefit from a heated mug, Ember is a good one. Other styles did well in my broader test of heated mugs, but I have returned to the Ember because it's comfortable to drink from (no burned lips!), easy to set and simple to keep charged. A bonus is the range of styles and sizes as well as colors.

Sarah Wharton led the Good Housekeeping Institute's testing of heated mugs, which included three of Ember's mugs. She has been using the Ember Mug 2 for more than a year. She has also covered related content such as the best travel coffee mugs and the best milk frothers.

Sarah (she/her) is a deputy editor for the Good Housekeeping Institute, where she tests products and covers the best picks across kitchen, tech, health and food. She has been cooking professionally since 2017 and has tested kitchen appliances and gear for Family Circle as well as developed recipes and food content for Simply Recipes, Martha Stewart Omnimedia, Oxo and Food52. She holds a certificate in professional culinary arts from the International Culinary Center (now the Institute of Culinary Education).

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