What we drink our coffee from matters. Disposable paper cups, while a definite improvement over the Styrofoam containers of the past, still generate significant waste. They’re typically made from virgin paper fiber and, according to the Journal of Cleaner Production, have a global footprint comparable to the annual emissions of 1.5 million Europeans. The United States is the leading offender of paper cup use: We go through around 136 million a day.
In addition to keeping your coffee hotter for longer and protecting you from spills, a stainless-steel travel coffee mug is a superior sustainability choice. The International Reference Center for Life Cycle Assessment and Sustainable Transition found that stainless steel had the lowest environmental impact over time of all popular coffee-drinking vessels, including ceramic mugs. However, that’s only true if you are devoted to using your mug regularly for several years and going easy on the warm water and soap.
So, yes: The most sustainable travel coffee mug is the one you already own. But if you are in the market, you’ll want one that’s secure, easy to sip from, and built to last. That’s why we put six popular travel mugs to the test, assessing vitals like how hot they keep your brew and how well they stand up to the occasional drop. We also dug into the sustainability practices of the brands behind them, including the materials they use and how they handle spent cups. Our winning travel coffee mug is not only a perfect fit for your morning routine, but also backed by a company that’s doing its best to not roast the planet.
one5c’s pick: MiiR Flip Traveler
The MiiR Flip Traveler ($33; miir.com) is a steadfast coffee companion: pleasant to drink from, simple to clean, and comfortable to carry. While it wasn’t our top performer, that’s not really a knock in this field, where only a few points separated top from bottom. The mug keeps coffee warm throughout the day and barely leaked throughout our testing. MiiR’s impressive sustainability practices are what catapulted this cup to our top spot. Among many notable efforts, the company uses eco-conscious packaging, runs a thoughtful take-back program, and holds a Climate Label certification for getting into the nitty-gritty of its emissions footprint.
Runner-up: Thermos Stainless King Drink Bottle
A rugged mug with exceptional heat retention, the Thermos Stainless King Drink Bottle ($33; thermos.com) earned second place overall and topped our performance tests. As durable as you’d expect from a brand long trusted on construction sites, the mug is comfortable to sip from and scored high sustainability marks. We especially appreciated that Thermos has cut emissions by 15% since 2019 and is working to be carbon neutral by 2050. The brand also collects and recycles old products.
What travel coffee mugs we tested
We tested travel coffee mugs from widely available brands that have earned strong ratings from both professional and everyday reviewers. The mugs we selected came in sizes ranging from 12 to 24 ounces, had lids that can be opened with one hand, fit in standard-size cup holders, and were priced between $25 and $36. They were:
- CamelBak Forge Flow
- Contigo West Loop Autoseal
- MiiR Flip Traveler
- Stanley AeroLight Transit Bottle
- Thermos Stainless King Drink Bottle
- Zojirushi Stainless Mug SMKHE
How we picked the best travel coffee mug
Our product recommendations are based on two parallel assessment tracks: one for performance and one for sustainability. These ratings combine to land on our final winner, which represents the ideal blend of a product that’s good for the Earth and for your life. Read more about our assessment process here.
How we tested travel coffee mugs
When each mug arrived, we visually inspected each one and explored any unique features, including the mechanisms that open the lids for drinking. We then cleaned them thoroughly, disassembling and reassembling each, and noted any that were particularly difficult. Over the course of a month, we used each mug around the house, while running errands, at children’s sporting events, and more. We also ran the following graded tests.
- Leak test: We filled each mug to capacity, turned it upside down, and shook it vigorously five times, measuring any leakage. We then placed each mug on its side and rolled it back and forth five times, again checking for any drips.
- Heat retention test: We filled each mug to capacity with 199-degree F water and recorded the temperature over a 12-hour span, checking the mercury at 1, 3, 5, 8, and 12 hours.
- Cleaning test: We cleaned each mug by hand, noting how easily any seals or gaskets could be removed and how thoroughly we could clean out any small or hard-to-reach parts. All of the mugs boast dishwasher-safe lids, but they all require you to pop off the gaskets and do some disassembly for a deep clean.
- Sip test: We drank from each mug while sitting, walking, and driving. We noted how comfortable each one was to drink from, how much they dribbled during use, and how much liquid accumulated in the lid when tipping it back.
- Drop test: We filled each mug halfway, dropped from hip height onto a cement driveway, and noted any damage or spillage.
How we scored sustainability
Our sustainability ratings take into account three factors: a product’s environmental impact at its production, what happens at its end-of-life, and the manufacturer’s environmental behavior. Production factors in where, how, and with what a product is made—as well as how it’s transported through the supply chain. End-of-life takes into account the toxicity of the materials used, the product’s warranty, whether the company sells spare parts, and how brands help buyers recycle old products. The final factor involves actions the company takes outside the life of a product to minimize its footprint or benefit the environment, and we award bonus points for transparency, as well. These scores are informed inferences based on available information, not full-blown life-cycle analyses.
How the MiiR Flip Traveler performed
The MiiR makes a strong impression right out of the box. It’s a slim, slick-looking cylinder that’s made from powder-coated 18/8 stainless steel and available in 12-, 16-, and 20-ounce sizes. While it doesn’t have a handle, it does have a textured finish that provides a secure, comfortable grip. When you’re not holding it, the MiiR fits well in standard cup holders and backpack pockets. The lid seals up tight but is still easy to twist off. As far as drinking goes, it features a flip-up arm that latches over the mouth to keep it covered. It works well: Testers encountered no spills or leaks of any kind.
But the big question is, what’s it like to drink from? In short: Great. The MiiR’s sipping spout hits the right angle and is just wide enough to let hot liquids flow at just the right rate—a nice, consistent stream that neither gushes nor dribbles—and the lid rests comfortably against lower lips for a tight seal. This was a clear improvement over the Zojirushi Stainless Steel Mug ($35; zojirushi.com), whose lid latch protrudes awkwardly, forcing drinkers to tuck their bottom lip between the latch and spout to take a swig, and the CamelBak Forge Flow ($30; Camelbak.com), whose wide fast-flow opening caused coffee to pool around the rim and made sipping messy.
You can also trust that the MiiR will keep your brew warm. After 5 hours, the 199-degree F water had a temperature of 147 degrees—which is still plenty hot for most coffee and tea drinkers. This heat retention placed it in the middle of the pack, though all mugs did well. For comparison, the Thermos, our overall performance winner, held its brew at 178 degrees at the same mark.
Cleaning is simple, too. The MiiR’s lid has only one small rubber gasket to remove before it can go in the dishwasher, and it doesn’t have too many nooks and crannies to reach. The Contigo Autoseal West Loop ($35.50; contigo.com), which features a very smooth and tight-sealing push-to-open trigger lid, and the Thermos were both similarly easy to scrub up.
Nothing’s perfect: While we found the MiiR’s flip-out arm mechanism easy to use, it did cause some minor issues. The mug fared the worst in our drop testing: It opened on two of the falls, although the vessel itself showed only one small, nearly unnoticeable dent and no paint chipping. The arm also doesn’t sit entirely flush when flipped open, which may be slightly uncomfortable for drinkers with a more pronounced nose bridge. Any discomfort was especially noticeable when we compared the MiiR to the Stanley AeroLight Transit Bottle ($30; stanley.com), which has a flip-lid arm that locks into place at a 180-degree angle for unimpeded sipping.
Why the MiiR Flip Traveler is sustainable
Since the majority of travel coffee mugs are made out of the same materials, factors like packaging, emissions, longevity, and circularity separate the field in terms of overall sustainability. In those areas, MiiR was the clear standout. For one, its packaging is minimal, mostly made from postconsumer recycled materials. Any freshly made paper products are Forest Stewardship Council–certified for responsible sourcing.
MiiR also has a take-back program for recycling its stainless-steel products. The kit for mailing back a spent cup does run $5, but the company provides a $20 credit for returned items. The brand also has a long, impressive list of top-tier sustainability markers, including a membership in 1% for the Planet and certifications from standards-setters like B Corp and the Tugboat Institute.
The company is also tackling emissions on many fronts. MiiR is Climate Label–certified, meaning it provides nitty gritty info on its carbon emissions and is actively working to reduce them. It has a goal to slash Scope 1 and 2 emissions (i.e., those from business operations and energy use) by 46% by 2030. It also has a self-imposed internal carbon fee that requires various departments to pay for emitting. The company then pools those fees to invest in external and internal sustainability initiatives like decarbonizing their supply chain and using more recycled materials.
Nothing’s perfect: MiiR gets a lot right. But it does perform below its peers in one area of sustainability: being totally upfront about its water consumption. In the company’s impact report, it boasts about excellent water purification at its facilities, and the firm works with nonprofits like Splash and Ecotrust that tackle the global water crisis. That’s all great, but we’d also like to see data on the company’s overall water use, which ideally would show that they’re lowering it. We also wish MiiR would use recycled steel and plastic in the mug.
The runner-up
The Thermos Stainless King Drink Bottle earned first place in performance and second place in sustainability, finishing a very close second overall. It’s a true workhorse of a travel mug: tough, spill-proof, and built for daily use. It was also the easiest cup to disassemble and clean. We liked its grippy body and found the twist-to-drink lid simple to use even in the bumpiest situations. It kept our 199-degree F liquid at a piping 151 degrees a full 12 hours after the initial pour, besting the next-best Zojirushi, a brand lauded for its heat retention, by 9 degrees.
Thermos also scored high sustainability marks—particularly for its efforts to cut carbon emissions, water use, and waste—just not to the same levels as MiiR. It has slimmed emissions by 15% since 2019 and is working to be carbon neutral by 2050. The company's also cutting water use in areas where it’s scarce. The company lost points for packaging due to a lack of sustainable materials, including sending the mug in a plastic sleeve.
Christian Dashiell is a freelance writer covering cooking, products, parenting, and lifestyle. He’s a certified barbecue judge and has written for publications such as Gear Junkie, Spy, All Things Barbecue, and Fatherly.
Tyler Santora is a freelance science journalist, editor, and fact-checker. He has written for publications such as Undark, Scientific American, Popular Science, and more.
one5c does not earn a commission on any product purchased through our reviews
