The Ember Mug 2 keeps your coffee at the exact temperature you pick, so it never goes cold while you work. Wirecutter has kept it on its mug warmer list since 2021, and in its testing the mug held drinks within about a degree of the set temperature.
How it works: a heater and battery sit in the base of a ceramic-coated mug. Pour in a hot drink and it switches on by itself, holds the temperature you set, and goes to sleep when it's empty. You choose the temperature in the Ember app on iPhone or Android, from about 120 to 145°F, and it can notify you when your drink is ready. The app also adds tea timers, presets and a personalized light.
Battery is the big question. Off the coaster, Ember rates the ten-ounce Mug 2 at up to an hour and a half, and Wirecutter found it lasted the longest of the self-heating mugs it tried. Leave it on the charging coaster and it keeps your drink warm all day, so the last sip is as warm as the first.
It shines for the long, slow cup: morning emails, video calls, reading, or the tea you keep forgetting about. That makes it a natural fit for remote workers, students and anyone with a half-finished coffee on their desk, and the copper and stainless finishes make it a nice small splurge as a gift.
The honest catch: it's hand wash only, the built-in battery isn't replaceable, there's no lid in the box, and changing the temperature means using the app over Bluetooth, which some owners find fussy. In September 2026 Ember launched the Mug 3, with buttons on the mug, top-rack dishwasher safety and an included lid, but the same listed battery life. Ember says the Mug 2 is still fully supported.
Our verdict: yes, if you sip slowly at a desk and hate reheating. If you drink fast or need hours of heat away from a charger, a good insulated mug will do.
