Nextmug vs. Ember: Which is the Best Self-Heating Coffee Mug?

The premise of these heated coffee mug is pretty simple: What if you could keep your drink at the perfect temperature for HOURS? This would obviously be better than the 5ish minutes you get in a typical ceramic coffee mug, or the few minutes more you’d get with a double-walled glass mug.

How do temperature controlled coffee mugs come to do this? The short answer is some computer smarts plus a little heater (or warmer plate) nestled in the bottom of the mug. That is really the whole idea that the Ember mug first pioneered, and of which Nextmug is one of the better-known-and-loved followers.

To give you the simple summary, the Ember is prettier and more controllable, but requires a smartphone app. The Nextmug is just as effective (and significantly more so if you use the included lid), but is less controllable and — at least to our eyes — a bit uglier.

If you’re not satisfied with that short Ember mug versus Nextmug comparison, let’s get on to the longer version. I think when we get down to it, the mugs are pretty similar. Other than a product tester like me, no one should own both of these things. So I’ll run down the differences and similarities, as well as the quirks and annoyances of these two coffee heating mugs.

Ember Mug: The Original

Ember really created and spearheaded the “electrical mug to keep your drink warm” space. It started with a very successful Indiegogo campaign in 2015 and then launched in Starbucks stores in 2016. (What a great break!)

In 2019, they launched the Ember Mug 2.0, which is what we’re considering today. These updates primarily increased the size of the battery and changed the available sizes,,which now 10 ounces and 14 ounces. As an owner of both (here’s my original rundown of the Ember mug), I can say the charging pucks and basic aesthetics were unchanged.

Today they also sell tumblers (a travel-compatible mug, including a version for iced coffee drinks) and a cool thing that is utterly irrelevant to this article called the Ember Cube, for cold-chain medical transit.

How the Ember Mug Works

The main way the Ember mug works is that it senses the temperature of your coffee (and I honestly couldn’t tell you how) and then kicks on the little electric heater when the temperature gets low enough that it thinks it should. Because both this sensing and heating are done via electricity, there also has to be an electrical connection from your wall (to your power generation plant 🤯 and) into the mug itself.

For the Ember, this is a color-matched puck which takes a barrel plug from the wall adapter, and has two small pins near the edge that go into the two metal rings on the bottom of the mug.

The Ember App

To control this whole system, Ember mostly relies on a smartphone app. While the mug does have a large soft button on the bottom that can do basic on-and-off, controlling the temperature of your beverage is 100% done via the app. This app has been around for years at this point, and doesn’t look dated at all. And it works pretty well. But it also is an app you’ve got to use, which always takes a few seconds to detect your mug after you launch it, etc.

In their defense, if you always want something like 136F, the power button alone is enough — you’ll only ever need to use the big bottom button. But if you’re curious to test different temperatures or whether your mug is fully charged (or about to die), off to the app you go.

Overall, it works really well. You get a fairly seamless experience dealing with a thing that truly feels like a magic trick the first few times you use it. It will amaze and surprise you to come back to a cup of coffee (or tea, etc.) and find it still at the perfect temperature.

Nextmug: Simpler Follower

Following the success of the Ember mug, there were a number of fast-followers. Truly, if you look on Amazon today you’ll find dozens more besides the Nextmug…

But, based on my research, the Nextmug is the most well-regarded, and I see why. Developed in beautiful Boulder, Colorado (where I went to school, Go Buffs), the Nextmug is simpler to use than the Ember (no app!), and still works very effectively.

And while I don’t know if they invented it (I’d guess not), the Nextmug also does a fairly crazy thing: it come with a lid. As we’ll see below, the lid radically improves the effectiveness of a keeping-things-hot mug. When unpacking my Nextmug that was my first thought: I’d never realized the absence of a lid on the Ember, but it makes a lot of sense to use one. And (spoiler alert) it makes the mug much more useful and viable away from its charging base.

How the Nextmug Works

Physically the Nextmug shares a lot with the Ember. The mug is much more bulbous, and the charging puck is black no matter what the color of mug. The core premise of a barrel plug going into the base with small pin contact points is the same as its predecessor, the Ember.

The big difference is that the Nextmug is controlled by a button (and only a button) opposite the mug handle on the lowest part of the base. This button is how you both turn off the Nextmug and cycle through the temperatures (only “Warm” 130°F, “Hot” 140°F, “Piping” 150°F).

This is very simple, but it does mean that you can’t hit 135F without doing some really silly dance between two settings.

As I mentioned, the Nextmug also comes with a lid. While you can ignore it, you really should consider it for thermal and battery reasons. Which is where we’re heading…

Some Nerdy Thermal Notes

You can research manufacturer claims about how these mugs perform, but you came here for proof I really care, so let’s go.

I did hands-on, manual thermal tests of both mugs: the lid-less Ember, and the Nextmug, both with lid and without. (Worth noting: You can buy a lid for your mug from Ember, or from one of the 100s advertising compatibility on Amazon. But it didn’t come in the box, so I’m not going to test that here.)

My heat retention testing methodology

Here’s how I tested these mugs: I heated water to 180F (which I felt was about the temperature I’d expect coffee to enter) and then added 300g to each mug. Then I just left them on battery-only, with a target temperature of 140F, and saw how long they lasted.

I also took their temperature (with an external thermometer) and noted the battery level each time. (The latter is a lot more precise with the Ember app than with the 3 LEDs that tell you the charge status of the Nextmug.)

The results

For the curious // more table-oriented among you, click here for the data in table format

Minutes	Ember Temp	Ember Battery Level	Nextmug w/o lid Temp	Nm w/o lid Battery Level	Nextmug w/ lid Temp	Nm w/ lid Battery Level
15	138	62	138	100	151	100
30	138	43	138	66	144	100
45	138	23, got app notification to charge	138	33	141	100
60	135	4	126	0	139	100
75	117	0	111	0	141	100
90	107	0	104	0	142	100
105	100	0	98	0	141	66
120					141	66
135					141	66
150					141	33
165					141	33
180					139	10 (blinking red)
195					136	0
210					129	0
225					122	0
240					117	0
255					112	0

A few methodological points:

• The Nextmug battery numbers are discontinuous (and inflated upward) because its battery power is just shown via 3 LEDs. So 100% means it was showing 3 LEDs, 66% 2, and 33% just 1. I gave the lidded-Nextmug credit for 10% because the single LED turned to blinking-red when I did that measurement.
• I didn’t measure the Ember and lidless Nextmug past 135 minutes. Mostly because I tested these BEFORE I saw how amazingly the lid improves the thermal performance of these mugs. It seems safe to assume they both fell at about the same rate down to my ~70F room temperature.
• Because life intervened, I didn’t keep up my every-15-minutes readings for the lidded Nextmug. But I came back and checked its temperature at 345 (15 minutes shy of 6 hours) and it was still at 94F. Just about where the other two were done when I stopped measuring them at 135 minutes (2 hours and 15 minutes). Wow! (This wasn’t graphed because the data point was so discontinuous and made the chart even sillier.

Thermal test takeaways

What does this tell us?

• If you don’t use a lid, and they aren’t on their charge, the Ember and Nextmug keep your drink at your target temperature for about 75 minutes.
• The Ember and lidless Nextmug performed similarly thermally, despite using their batteries at different rates. Both were at 138F through 45 minutes. By 60 minutes, the Ember was at 135F and the Nextmug at 126F; both batteries were essentially exhausted around that point. Once the batteries died, their cooling curves remained fairly similar.
• The lidded Nextmug is the real story. It stayed essentially at the 140F target from 45 through 165 minutes, and was still 139F at 180 minutes. That means it maintained roughly the target temperature for about three hours — roughly three times as long as either lidless mug.
• The lid helped even after the battery died. The lidded Nextmug was still 112F after 4 hours and 15 minutes and 94F after 5 hours and 45 minutes. At that point, the mug wasn’t actively heating anymore; the lid was simply helping it lose heat much more slowly.
• Interestingly, the lid also dramatically extended the Nextmug’s battery life. Without the lid, its battery was depleted at about 60 minutes. With the lid, it didn’t hit zero until around 195 minutes. Presumably, retaining more heat meant the mug’s heater didn’t have to work nearly as hard to maintain 140F.

Again, I didn’t test the Ember lid, so I can’t say it would produce the same results. But I’d expect adding a lid to substantially improve its heat retention, too.

Showdown: Ember vs. Nextmug

OK, let’s get down to making the decision. Should you choose a Nextmug or an Ember mug? Let’s start with what the two share…

Pluses and Minuses the Mugs Share

Here are a few things that I’d say are nearly identical about the mugs:

• They’re both heavy. My favorite ceramic mug — which is large and a bit hefty — weighs 418g. An empty Ember mug clocks in at 455g and the Nextmug at 517g. Not a massive difference, but noticed when I hand them to everyone. If you’ve got good hand and arm strength, this isn’t that big a deal. And loaded with a 10oz coffee drink the sharpness of the difference fades. But worth considering.
• They’re both battery-powered. This means both that they’ll keep your drink warm when you’re not at the charging station. But they’ll only do that for a bit over an hour (as per my test above).
• They’re not dishwasher safe. Both of these mugs, understandably given all the electronics inside, are hand-wash-only. It makes sense, but it’s still a big change for most people who have 5-20 mugs which they thoughtlessly throw in the dishwasher day-to-day, week-to-week.
• They both come in various sizes and styles. While much of my comparison here focuses on the “conventional coffee cup” style of smart mug, both of these brands also have a commuter/travel mug-style, and some other sizes.

The Case for the Ember Mug

I think the big reasons I’d pick the Ember mug over the Nextmug are that…

• I value the aesthetics. I’m about 40% sure that the Ember mug’s shape is more pleasing than the Nextmug’s. Megan feels 100% sure. Either way, I do think most people will find the Ember mug a little sleeker and prettier.
• I want degree-specific temperature control. The Ember app lets you set your “hot water” temperature down to the HALF DEGREE (FAHRENHEIT)! That level of control is really cool, and does honestly make a difference to my experience between the two. Following Ember’s recommendations, I prefer my coffee to stay at 135F. On the Nextmug I simply can’t select that temp because it only offers 130, 140, and 150F. 140 feels a bit too hot, 130 a bit too cold, and on the Nextmug, I simply can’t select anything between.
• You like apps. I already highlighted this a bit above, but Ember is controlled (other than a crude on/off) with the app. This is great if you like smartphone apps for your devices, and obviously a real downside if you don’t.
• I like that cool under-the-mug double ring I highlighted in my Ember Mug review. I think drinking from an Ember mug on a video call is a cool weird flex. You probably don’t. ;p

The Case for the Nextmug

I’d pick the Nextmug if…

• I wanted to reduce my smartphone use or, more broadly, the complexity of the devices in my life. Especially as we’re starting to hit the smartphone backlash, I think the low-tech nature of the Nextmug controls will likely appeal to many. Just one button, you hit it and the temperature changes. No phone required!
• I want the thermal efficiency provided by that sweet-sweet Nextmug lid. I was truly wowed (see Nerdy Thermal Notes above) by how much more efficient the lidded Nextmug is than either the Ember or the Nextmug without a lid. This is the most basic of physics/thermodynamics — the same logic that leads people to tell you to wear a hat in winter because “you lose 80% of your heat through your head” — but I was still surprised both that the Nextmug came with a lid and that it made a HUGE difference in how long the not-charging mug could keep my drink at a good temperature.
• I’m less worried about the reliability of Nextmug’s charging bases. I speak here from personal experience that my Ember Mug 1.0 died because the charging base pins got stuck. When I couldn’t charge it (and my efforts to repair it led to a bit of an electrical problem) I gave up on it. The Nextmug design doesn’t scream “rock-solid durable,” but I’ve not seen nearly as many complaints online about it.

Which Must is Right For You?

Really I see this as mostly a matter of “hip aesthetic” versus “practicality.” As you might expect, I find the Ember the answer to the first, the Nextmug better at the second. But it is more subtle than that.

First, some people choose to opt out of this dichotomy entirely. And I respect that. If you’re game to use a thermal travel mug for your coffee inside your home instead of a “normal” coffee mug, you’ll get 80% of the thermal value of this kind of device without any electricity. But I know that’s not for everyone, and these gadgets are more fun.

So if I’m game to spend $15 on an Ember lid, I’d probably pick the Ember on most aspects. But I’m a person who has made my peace with the demons of “smartphone addiction,” and I do appreciate the extra temperature control and battery read-out in the Ember app. Plus I think it just looks a little better.

But if I hated (or didn’t possess) a smartphone, I’d get the Nextmug for sure. It is a nice simple interface in every practical way. And including the lid is just smart thermodynamics and makes my life easier.

Which one will you pick?