We’re Drinking Hot Coffee All Day Long, Thanks to These 3 Temperature Control Mugs

On the spectrum of “indispensable kitchen gear” to “goofy-but-fun gadgets,” temperature control mugs fall… well, you know where they fall. Do we, Serious Kitchen People, believe a battery-powered mug that keeps your joe hot, is a must-have appliance? Admittedly, no. But we’ll also admit that they’re nice to have, especially if you’re a sip-not-slurp kind of coffee drinker. A handful of Serious Eats editors have temperature control mugs, and yes, we really do use them.  

But are temperature control mugs better than simply microwaving your coffee? Consider this: coffee’s flavor changes as it cools, so even if you do nuke your mug, the flavor will have been irreparably altered, and not for the better. In other words: You can heat it back up, but you can’t restore that freshly brewed flavor. So what’s a slow-drinking coffee lover to do?

We tested 13 temperature control mugs and warming pads to see which ones did what they promised (kept coffee hot) and weren’t annoying to use (nobody wants to fiddle with faulty buttons). The result? We found two temperature control mugs that were a joy to drink from, plus one great warming pad that can be used with whatever coffee mug you’ve already got.

The Winners, at a Glance

The Best Temperature Control Mug

Ember Travel Mug 2

$298 at Amazon $249 at Walmart View on Ember.com

There’s nothing this mug can’t do. Along with a digital thermometer that gives temperature readings in real-time, the Ember Travel Mug can also be controlled using the brand’s easy-to-use app. At 12 ounces, it had the largest capacity of all the mugs we tested, as well as a handsome touch display.

The Best Coffee Mug Warmer

Sweetfull Coffee Mug Warmer

$30 $24 at Amazon

While the Ember Travel Mug was the priciest option we tested, the Sweetfull Coffee Mug Warmer was the least expensive. It did exactly what it needed to do: It kept coffee consistently hot. The warming pad featured three temperature settings, and it was the biggest one we tested. Plus, it works with whatever mug you already own. It does take up a bit more counter or desk space, though, and if you’re traveling with it, you’ll need to make more room in your pack.

Editor’s Pick

Ember Temperature Control Smart Mug 2

$130 $90 at Amazon $150 at Williams Sonoma $90 at Target

The Ember Mug 2 is a more traditional pick for at-home coffee drinkers and is ideal for use at a desk. It has a sleek look that’s still comfortable to hold (the roomy handle is great), and it comes in loads of fun colors. “I have the rose gold Ember mug and I use it nearly every day,” says associate editorial director Riddley Gemperlein-Schirm.

The Tests

• Charging Time Test: We recorded how long each mug took to fully charge out of the box. The mug warming plates weren’t part of this test because all of them are plug-ins without internal batteries.
• Temperature Hold Test: After charging, we poured each mug’s capacity of hot coffee into it and set each one to 135°F (if a specific value could be set), testing its temperature using an instant-read thermometer every 10 minutes for 90 minutes to see how it held temperature off of its charging station. We did the same with the mug warming pads, but each was plugged in to see how long it would last before going to sleep.
• Long-Hold Test: We placed each mug on its charging or warming pad, poured each mug’s capacity of hot coffee into it, and took temperature readings using an instant-read thermometer every 40 minutes for four hours at the highest temperature settings. 
• Accuracy Test: We placed each mug on its charging or warming pad, poured each mug’s capacity of hot coffee into it, and measured temperature readings (if specified) against both the lowest and the highest temperature it could be set to. We gave all of the mugs a grace period of -/+ 3 degrees.
• User Experience Test: Of course, we drank from the mugs. We noted how easy or difficult each was to use. Were the settings easy to figure out and use? 
• Smart Features Test: Some of the mugs had smart features. Did they enhance the experience, or were they confusing and glitchy?

What We Learned

Without a Temperature Control Mug, Coffee Cools Off Quickly

Even though the first sip may seem scalding (It’s so hard to wait!), coffee cools quickly when left to its own devices. But if you're the type to set down a cup of coffee and immediately get distracted, you probably already know that. In our round of long-hold testing, we also measured how a coffee fares in a traditional coffee mug. We used an amber glass mug as a control, and were astounded to see how much it cooled off in the first ten minutes alone. Its temperature dropped almost 40 degrees! By the end of our 90-minute test period, the glass mug of coffee had lost 94 degrees. Check out the chart below to see how the temperature declined.

After seeing these results, we understood that the temperature of coffee is similar to the ripeness period of an avocado: It takes forever to be ready for consumption, there's an impossibly short period where it's perfect, and then it begins to rapidly decline in quality. All this to say, even if temperature control mugs seem a little silly, they really do solve a common problem.

135˚F Was the Magic Number

If you're looking for a mug warmer or temperature control mug that lets you set a temperature down to the tenth of a degree, you're going to have to keep looking. None of the mugs we tested were that precise (although we've tested some fantastic electric kettles that do get down to business like that). In fact, most of the mugs we tested offered a standard preset temperature of 135˚F. And the mugs that didn't offer any temperature customization all flirted with that temperature.

At first blush, that may seem too cool. After all, the ideal brewing temperature for coffee is around 200˚F (you can read more about the art of pour-over brewing here). But research has shown that most coffee drinkers prefer their coffee around 136 to 140˚F. What this means for our purposes here is that you aren't missing anything if your temperature control mug can't get blisteringly hot. As long as your coffee stays close to 135˚F, your palate will perceive it as pleasantly warm.

Most of the mugs we tested were able to hold temperature at 135°F for at least an hour. This factor is more reliable if the mug is actively sitting on its charging pad. Both the Ember Mug and Cup were supposedly able to hold a charge for 90 minutes. The ionMug claimed it could handle three hours, and the VSITOO promised eight hours at the lowest temperature setting. But every one lost battery power at the 70-minute mark when taken off the charging pad. (The mugs were able to keep a consistent temperature for four hours when kept on their pads.)

Some Mugs and Pads Had a Frustrating User Experience

The temperature control mugs and coffee warming pads we tested all did what they said they’d do: keep coffee warm. The Ember Mug 2 and Ember Travel Mug had a pleasurable-to-use, easy-to-navigate app but they were the exception. The rest of the mugs and pads we tested lost points for finicky controls and frustrating interfaces. The OHOM Self-Heating Ceramic Mug, for example, supposedly doubled as a phone charger but our mobiles remained at low battery—we couldn't get it to work.

Warming pads were hit or miss when it came to basic features. Some, like the Kin Intelligent Mug Warmer and Bestinnkits Smart Coffee Cup Warmer, were gravity-operated. Just place the mug on the pad and it will activate the heat. The Cosori Coffee Mug Warmer and OHOM mug regularly shut off after an hour. This wasn't a big deal in the case of the Cosori—we just pressed a main power button to turn it back on. But the OHOM had to be unplugged and re-plugged... and sometimes, that didn't even do the trick.

The mugs had similarly variable performances. We mentioned how great the Ember's app was to use, but we didn't love the fact that the Mug 2 and the smaller Cup's temperature control button doubled as the power button. The Ember Travel Mug 2, on the other hand, has a futuristic touch function. Just tap the logo on the cup, and a temperature gauge will light up. Use that to set your ideal temp

Looks Mattered!

Coffee mugs (and espresso cups, for that matter) are incredibly personal. A good one can make your morning, and a bad one can set off a chain of "terrible, horrible, no good, very bad day" events. And just because a temperature control mug shares some qualities with techy appliances doesn't mean it has to look utilitarian.

Our favorite mugs and warming plates had a lovely aesthetic. The Ember Mug comes in loads of handsome colors, including powder blue, sage green, and a collection of eye-catching metallics. The Ember Travel Mug offers just basic black, but it's sleek and understated. The Sweetfull pad has three color options, including a faux wood finish that looked surprisingly chic.

On the other hand, we cringed at the Cosori's utilitarian stainless steel and grippy rubber aesthetic. The Ikago mug was nice-looking enough, but the digital display reminded us of a 1980s alarm clock—not cute. Ultimately, we felt strongly enough about a coffee mug's role in the expression of one's personal style that its design did matter.

The Criteria: What to Look for in a Temperature Control Mug or Warming Pad

We liked temperature control mugs and warming plates that delivered on their stated promise: They kept coffee at a pleasant temperature over an extended period. The best mugs kept coffee hot even off the charger and had helpful smart functions. How the mugs and pads deliver information matters, too. Mugs should clearly and accurately signal that they’re fully charged, in need of a charge, or at your desired temperature. The best mugs, like the Ember, were easy to understand and use. Finally, temperature control mugs should be easy to clean and comfortable to handle—just like any other coffee mug!

Our Favorite Temperature Control Mugs and Warming Pads 

The Best Temperature Control Mug

Ember Travel Mug 2

$298 at Amazon $249 at Walmart View on Ember.com

What we liked: For starters, the Ember Travel Mug is the only mug we tested that relies on old-fashioned keep-warm design: Even “basic” travel mugs can keep coffee hotter for longer. It simply kept the most consistent temperature both on and off its charger. Also, because of their tall, lidded design, less coffee is exposed to oxygen, so it oxidizes at a much slower rate. 

The Ember Travel is also the “smartest” mug we tested. Although the Ember Mug 2, Ember Cup, and the Ember Travel also use the same app to control temperature, the Ember Travel displays temperature readings in real time. (The Ember Mug just has a light on the bottom that flashes different colors.) When we initially poured coffee into the Ember Travel, it gave a reading of the coffee’s current temperature. However, there was a threshold: When we poured cold water, the mug simply read “cold.” It flashed the word “empty” to indicate when there was no liquid. 

The app for the Ember comes with preset temperatures for a variety of drinks. It’ll hold other liquids at an ideal temperature (great for tea) and you can set a customized preferred temperature setting or just rely on one of the defaults already programmed. It also has a Find My Mug feature, which is important because it’s pricey, and the feature helps protect your investment in it. 

What we didn’t like: The Ember Travel is the most expensive mug we tested. Because the Ember Travel is designed to go into sleep mode after three hours, it was difficult to “remind” the mug we were still using it. We had to pick it up and fiddle with the app a few times before the mug kicked back on. If you prefer drinking out of a traditional mug, this won’t be a good fit for you. Finally, although you can set your ideal temperature down to a degree, the temperature range is limited. The mug will only keep liquid warm between 120 to 145°F, so if you want something hotter or cooler, this mug can’t do it.

Key Specs

• Type: Travel
• Materials: Stainless steel, ceramic coating
• Capacity: 12 ounces
• Weight: 2.4 pounds
• Temperature range: 120 to 145°F 
• Stated battery life: 3 hours
• Charging time: Approximately 3 hours
• Care instructions: Hand-wash only

The Best Coffee Warming Pad

Sweetfull Coffee Mug Warmer

$30 $24 at Amazon

What we liked: The Sweetfull doesn’t have bells and whistles. There are no digital displays presenting temperatures. (This is a mark in the “Positives” column, because we found many other models displayed inaccurate temperatures.). The simple Sweetfull is just a plug-in cord and a power/temperature control button, but what it lacks in brains it makes up for in brawn. With its ample 5.2-inch-diameter heating surface, there is plenty of room to work with. (Go ahead and pour your coffee into a bowl.) It kept coffee consistently hot, between 130°F and 140°F for the length of the four-hour-long hold test. Unlike other devices, it doesn’t have a built-in shut-off function. If you’d like a hot, reliable cup of coffee next to your computer all day without having to fuss with the device, that’s an asset. It’s just a reliable workhorse at a bargain price. For $23, it’s the least expensive of all the devices we tested.

What we didn’t like: This warming pad is rather bulky. Given its size, you may need a large desk or table to fit it. We weren’t fans of the all-in-one button that both controlled the pad’s temperature and turned it off and on. If you tend to be forgetful, the lack of an automatic shutoff function could be a problem.

Key Specs

• Type: Warming plate
• Materials: Plastic, glass
• Capacity: 5.2-inch-diameter heating panel
• Weight: 13 ounces
• Temperature range: 105º to 180°F 
• Stated battery life: Plug in, but shuts off after 4 hours
• Care instructions: Wipe with damp cloth

Editor’s Pick

Ember Temperature Control Smart Mug 2

$130 $90 at Amazon $150 at Williams Sonoma $90 at Target

What we liked: The Ember mug is sleek and beautiful and has nailed the stay-warm technology. It comes in loads of colors, which makes it fun to gift. There’s a smart LED bulb in the base of the mug that lets you know when it reaches optimal temperature. It reached a full charge in a little over two hours. During the temperature hold test, it consistently held at 130˚F, and at 70 minutes a polite alarm reminded us to put it back on its charging pad. “Its handle is wide and has a rounded edge that’s comfortable to hold onto, too,” Riddley says. 

What we didn’t like: Like the Ember Travel Mug, the Ember Mug is expensive. Because there’s no lid, it cools more quickly than the Ember Travel when removed from the warming pad. “I had an Ember mug that broke after about a year and a half,” Riddley says. “That said, I use it so often I immediately bought a new one.” 

Key Specs

• Type: Warming mug and plate
• Materials: Stainless steel, ceramic
• Capacity: 14 ounces
• Weight: 16.1 ounces
• Temperature range: 120º to 145˚F
• Stated battery life: 80 minutes at 135˚F
• Care instructions: Hand-wash mug; wipe the unplugged base clean with a damp cloth

The Competition

Temperature Control Mugs

• Ember Cup: This is a very handsome cup. With its weighted bottom, the handle-less body feels good to hold. But it’s so small and has such a wide, lidless opening that it had a difficult time keeping coffee warm: The heat just flew out the top.
• VSITOO S3 Pro Temperature Control Smart Mug with Sliding Lid: This smart mug took three hours to charge, and it did not last 90 minutes—let alone the stated eight hours! The smart controls were problematic. Every time we walked out of the room, we got a notification asking us to reconnect the mug and app. On the mug itself, the temperature controls were only displayed in Celsius. To change them, you need to use the power button on the bottom, which is confusing.
• ionMug & Charging Coaster: Although this was the budget pick in the first round of testing, it didn’t perform well in the second round. The temperature display on this mug was small and difficult to read, and the battery died rather quickly, lasting no longer than 70 minutes.  
• Nextmug Self-Heating Mug: This is an attractive mug, and it comes in an array of colors. But it took a full three hours to charge, and it would shut off inexplicably after just a few minutes of use. Its middle-temperature setting did not hold the coffee at the promised 140°F. 
• Thermacup Self-Heating Mug: The blue color was pleasing, and the controls and display were straightforward. The lid, however, was difficult to remove without spilling coffee, and it didn’t do a lot to retain heat. At the time of writing, it was no longer available.

Coffee Warming Plates

• Ikago Coffee Mug Warmer & Mug Set: This warming pad used infrared technology to get an accurate read of the temperature of the cup, and we could program it to an exact temperature. The readout also showed the cup temperature versus the programmed temperature, which was helpful. But it shuts off after two hours of inactivity—other pads last longer. 
• Kin Intelligent Mug Warmer: There wasn’t much “intelligent” about this mug warmer. It was a simple, gravity-activated pad with three vague settings controlled by a single button, which was also the on/off switch. The settings were on the cool side, and though it came with a silicone lid to place atop whichever mug you use, the pad didn’t reliably keep coffee warm. 
• Bestinnkits Smart Coffee Cup Warmer: This pad was so lightweight that we had to use a heavy cup to gravity-activate it. The word “smart” is deceptive. It was not very efficient and was far more flimsy than the Sweetfull, at three times the cost.
• Cosori Coffee Mug Warmer: This warmer came with a metal cup, which was not pleasant to drink out of. It was difficult to program accurately, too. Though a few degrees either way might still be considered accurate, with the pad displaying digital numbers, we expected exactitude and didn’t get it.
• OHOM Self-Heating Ceramic Mug: Like other pads, the OHOM didn't have a battery and only worked on the charger. Made of ceramic, this was one of the more attractive mugs we tested and it comes in a range of colors. Most of the mugs came with a travel lid—this one had a breakable, precarious ceramic lid. Despite moving it around to tell the charger it was still in use, it went into “sleep” mode after an hour. Unplugging and re-plugging it in didn’t always make it work again. 

FAQs

Is the Ember Travel Mug worth it?

That depends on how much money you would pay for a mug that keeps a big pour of coffee at the temperature you want for hours on end. The Ember Travel Mug is expensive, but with a leakproof, screw-on lid; narrow, heat-trapping design; and multiple ways to control temperature, including friendly, touch-sensitive display and smartphone connectivity, it certainly works as advertised. Given the price of a good pound of coffee these days, you’ll get your money’s worth with the Ember Travel Mug because you’ll have a consistently hot, fresh sip. And with frequent sales, you might snag one for nearly half the list price.

Why are temperature control mugs so expensive?

These mugs are equipped with lithium-ion batteries, the same type of battery as your smart phone, and those don’t come cheap. It’s also a relatively new technology, introduced by Ember in 2014. Chances are the prices will come down as more brands come on the market. Thermacup and VSITOO are already only around $90 compared to $200 for the Ember Travel Mug.

Can a temperature control mug heat up cold coffee?

Coffee tech nerds have tried this, and while they have found that, yes, technically, you can heat a cold cup of coffee in a temperature control coffee mug, it will take far longer than just throwing the coffee in the microwave or heating it gently on the stove. You’ll need to fiddle with the mug so that it doesn’t turn off on you, and you’ll run the battery down in the meantime. Leave the mugs to what they’re made for: keeping a hot cup of coffee warm.

What’s the difference between a hot plate and a temperature control warming plate?

A hot plate is a cooking device. Essentially, it’s a standalone burner, and its temperature will get quite high, often into the 500°F range. A temperature control warming plate is meant to do what it suggests: warm things, not cook them. You don’t want to boil your coffee; you want to keep it at a temperature that makes it pleasant to drink. That’s why for coffee you’d use a temperature control warming plate.

Why We're the Experts

• Betsy Andrews is a James Beard- and IACP-awarded journalist who writes primarily about drinks. She's been a regular Serious Eats contributor for years, and has also contributed to our review of coffee mugs.
• For this review, Betsy tested both temperature control mugs and mug warmers and re-reviewed our favorites from last year.
• Rochelle Bilow is an editor at Serious Eats. Previously, she worked at Bon Appétit and Cooking Light.
• For this review, she helped test temperature control mugs.