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We have the technology to prevent lukewarm coffee.
Most people agree there is no place for lukewarm coffee. If coffee is not cold — homemade iced latte, anyone? — it should be hot. But if your morning cup of joe gets interrupted frequently or you're just a leisurely sipper, you might find yourself reheating coffee in the microwave. But there's another way: Don't let the coffee cool down in the first place. Enter, the heated mug.
The pros in the Good Housekeeping Institute Kitchen Appliances and Innovation Lab tested 10 heated mugs to find the best picks. Of those 10, half were self-heating, meaning they have a built-in battery that heats the mug, and half were warming plates, which plug in and act as a gentle "burner" to heat the mug. We tracked their ability to keep coffee warm and keep it tasting good to the last drop.
Read on to learn more about how we tested heated coffee mugs and what to consider when shopping for one. And if you're not a coffee drinker, no worries! These are great for warming cocoa, broth and healthy teas as well.
The Smrtmugg Pro performed best in our Lab tests. It's a great option for people who want a self-heating mug with a traditional mug style. It has a large comfortable handle, and we appreciated the 14-oz size (it was the largest of the self-heating mugs we tested). We also appreciated that the onboard controls were intuitive: Simply turn the mug on and then press the illuminated button to move along the temperature scale that's marked on the mug. The button even glows blue, orange or red to denote cool, warm or hot.
Our pro noted that the Fahrenheit intervals marked on the mug may seem unusual (95˚F, 113˚F, 131˚F and 149˚F), but they make a bit more sense on the version of the mug displaying Celsius (35/45/55/65). The included slide-closed lid helped keep coffee hot — the Smrtmugg Pro held coffee at about 141˚F for the last three hours of testing — but it was a little bulky and can bump your nose when you're drinking.
The Cosori kept coffee the hottest in our tests thanks to an effective warming plate and a simple lid. The warming plate is unique in that it lets you set the temperature of the plate itself (in 1-degree intervals). The owner's manual shares the correlation between the plate temp and the beverage temp for added precision. Cosori also offered the largest capacity mug in our test at 17 ounces.
Our caveat is that the mug is stainless steel, and it got dangerously hot when the plate was set to its maximum temperature, so use caution when drinking from it. We found the mug was more usable when we dialed down the plate's temperature. We noted that the plate also worked well — even at the hottest setting — with a flat-bottomed ceramic mug.
This self-heating mug lets you set your desired temperature with controls on the mug itself. Simply press the large button on the bottom to turn it on and then tap the Ember icon for a menu. It also pairs easily with Ember's smart app, which lets you control multiple Ember devices remotely. It held coffee at a nice, hot temperature for most of its three-hour claimed battery life, and it only fell slightly below the target temperature of 135˚F in the last 15 minutes. We appreciated that the design of the lid allows you to drink from any side (you depress a disk in the center of the lid to open it). This friendly mug will even tell you hello and goodbye, so there's no confusion about whether it's on or off. As a bonus, it did not leak during our tests.
Ohom's Ui Mug earns its place on your desk or counter by offering multifunctionality: Not only did it keep coffee warm for 90 minutes when the lid was in place during our testing, the Qi warming plate can also be used to charge your cell phone and even some wireless earbuds. The sleek mug is available in a range of colors, and we found it comfortable to drink from (though the lid does become hot and condensation can drip from it as you lift and replace it). Like all the warming plates in our test, the Ohom plate gets hot during use, but because it doesn't have the same protective housing as others on our list, you'll want to use extra caution when moving it.
The control panel for Smrtmuggs's travel mug lives solely on the mug, making it an easy grab-and-go choice. The large battery on the bottom — the manufacturer claims a 10-hour battery life — enabled the cup to hold coffee above our target temp of 135˚F for the full four hours of testing. That hefty battery did make the cup feel heavy for its size, but we found it comfortable to hold. Our caveat is that while the push-button lid is easy to use, the edge of the bottom button can bump your lip when you're drinking, which is distracting. We also found that there's a bit of a learning curve with the tap vs. press-and-hold menu on the controls, but the clear digital readout was helpful in setting the temperature and turning off the mug.
The Ember Cup is designed for the smaller, more intense flavor of espresso and espresso-based drinks. The 6-ounce size fits under espresso machines with portafilters as well as single-serve and fully automatic machines. Our pros found the clean lines of this heated mug appealing, but some may miss the handle of a classic demitasse cup. It's easy to use — simply push the large button on the bottom — then pair it with the Ember app to set your temperature preference, which defaults to a drinkable 135˚F. Take note: For much of the claimed 90-minute battery life, this cup was just shy of that 135˚F target. We also liked the size and feel of Ember's 10-ounce mug, which can work for espresso drinks but might be a better fit for drip or French press coffee.
The experts in the Good Housekeeping Institute Kitchen Appliances and Innovation Lab test heated mugs for heat retention, impact on taste and ease of use. To test heat retention, a thermocouple (a thin, wire-like thermometer) is inserted into each mug. The thermocouple relays the temperature of the coffee in the mug to software that tracks the heat level over a four-hour period. This helps us determine whether users can actually have their drinking time interrupted and then come back to a warm cup of coffee. Some of the self-heating mugs gave a stated battery life of fewer than four hours, which we factored in when making our picks.
To determine how the coffee tasted over a two-hour period, our testers tasted a control cup and then coffee from each mug every 30 minutes, making notes about the bitterness, acidity, mouth feel and temperature sensation. Unsurprisingly, we found the coldest coffee the least appealing. We also felt that — compared with freshly brewed coffee — the mugs that kept coffee warm made the coffee taste worse over time.
When assessing ease of use, our Lab pros considered the helpfulness of the owner's manual, the type and readability of any controls, the feel of the mug, the comfort of drinking from it and the cleanability. They also evaluated the ease of opening and closing the mug and its leak resistance, if applicable.
✔️ Type of heated mug: The biggest consideration is whether you want to warm a regular mug on a heating plate or use a battery-powered mug that is portable once charged.
✔️ Lid: We found that whether you opt for a warming plate or a self-heating style, a lid goes a long way. It helps to trap heat from the start, which helps even weaker mug warmers. It also keeps liquid from evaporating, which can make the coffee taste more concentrated over time.
✔️ Capacity: For warming plates that come with a mug and for self-heating styles, check the capacity of the mug. The largest mug capacities we tested were 17 ounces for a warming plate and 14 ounces for a self-heating mug. If you know you need a big cup in the morning, you might want to be able to use your own mug.
In a word, yes. Many will, indeed, keep your coffee hot — some will even do so for hours. By and large in our testing, the self-heating mugs performed better than the warming plates, but much of that also came down to whether the mug had a lid. People who prefer a piping hot cup and choose to reheat their coffee may appreciate the more hands-off solution of a heated mug.
The caveat of our learnings is that the taste of the coffee can change if it's held at a hot temperature over a long period — this was true across the board, no matter which mug style was used. Each cup tasted more bitter or more acidic (or, in some cases, both!) as it continued to "cook," but we found that for shorter periods, heated mugs did keep coffee hot and that warmer coffee was more palatable than cooler coffee.
Sarah Wharton is the Senior Editor and Analyst for the Good Housekeeping Institute. She contributed testing and writing to our selection of the best travel coffee mugs. She's also written coffee advice for Good Housekeeping, including how to make a cappuccino and how to make a latte. Sarah lead the testing for these heated mugs, helping to develop the testing methodology with Kitchen Appliances Lab Director Nicole Papaptoniou.
Nicole Papantoniou oversees all testing of kitchen gear for the Good Housekeeping Institute, including products like coffee grinders, coffee makers, espresso machines and Nespresso machines. She is also the lead judge in the Good Housekeeping Institute's forthcoming Coffee Awards.