For many, drinking a morning beverage is more than a routine—it’s a sacred ritual. Whether you drink it en route to the office or the trailhead, you’ve likely adopted a favorite travel mug to carry your magical morning elixir. But do you know how its performance stacks up against the competition? Instead of relying on haphazard observations and product claims, the ϳԹ Lab @ CU Denver set up an experiment to find out which travel mug keeps beverages warmest the longest.
In the lab—a new test facility in the university’s engineering department—we used professional lab thermometers to determine which insulated travel mugs and bottles kept drinks hot at room temperature and in a cold setting the longest. We rounded up 24 of the most popular products available, divided them into three categories (tumblers, travel mugs, and thermoses), and got to work.
We tested the products in each category identically and compared only the results from our objective tests. Below are the products that performed best in each category.
What the ϳԹ Lab Tested
We selected popular models of the three most common types of insulated travel mugs and bottles specific to hot drinks.
- Spill-Proof Tumblers: Mugs with lids that typically slide or flip open
- Leak-Proof Travel Mugs: Bottles with a fully sealed “drink through” lid that can be thrown in a bag without leaking
- Traditional Thermoses: Large bottles that keep drinks warm all day
Note: Several brands use lead soldering to seal their products in manufacturing, a process still approved by the FDA. Though the lead never touches the inside drink surface, and rigorous testing is done to ensure no lead exposure to customers, this is a potential health concern if the product is damaged. We didn’t test for lead, but noted those companies which acknowledge using this method in their manufacturing process.
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How We Tested Travel Mugs at the ϳԹ Lab
To test the heat retention of each container, we filled them with hot water and used a lab grade digital thermometer with wire thermistor probes (thin temperature-sensitive wires) to take the temperature of each travel mug or bottle every hour and each large thermos every six hours. This let us get a quick, accurate temperature reading without fully removing the lid, preserving an accurate representation of real-world use. At the beginning of each test, we used an infrared camera to look for any noticeable heat leaks, but failed to find any significant enough to point out.
We set the start and end points for what constitutes “hot” in our testing based on common brewing, serving, and drinking temperatures for coffee. Start temperatures were different depending on the category of travel mugs being tested. Tumbler and leak-proof mugs started the tests at 165 degrees Fahrenheit, considered the standard serving temperature for coffee which needs to cool slightly before drinking. Large thermos bottles were started at 180 degrees Fahrenheit, the low end of brewing temperature (found at the finish of brewing), but too hot to safely drink. A higher start temperature was used for this category since it’s typically filled with the intent to pour the beverage into a cup later and let cool before drinking. We stopped all tests once the water inside the bottle reached 125 degrees Fahrenheit, which, according to brewers, is on the low end of the accepted drinking temperature for coffee that is still considered warm/hot.
The lab setting lets us control key variables like environmental temperature, allowing us to create conditions for each category that simulated their typical use environment and remained stable for the full length of each test. During each test we used a second thermometer to track temperature and humidity over long periods of time, verifying the environment remained stable. All samples were first tested in a controlled room temperature environment (70 degrees Fahrenheit) with their lids fully sealed to set a performance baseline.
Since tumblers aren’t often exposed to cold temperatures for very long duringcommutes and at the office, we only tested them at room temperature. Samples were also tested with the drink mouth left open to add another data point to the performance and help sort those that had similar results when closed.
Travel and thermos bottles, however, are often exposed to cold environments for hours at a time, such as when thrown in a pack or set on the ground while we’re out exploring. These two groups were placed in a controlled refrigerator set to 39 degrees Fahrenheit to mimic the cold environment and stress their performance limit.
At the end of the temperature test we closed the lid on each sample and tested for leaks. Prepared to get wet, luckily no longer by hot water, we shook each sample and then turned them upside down for one minute. All of the leak-proof labeled bottles passed without a drop, making our lab tech happily dry.
Results
Spill-proof Tumblers
The term “tumbler” is used to describe a lot of products, so we stuck to those that hold 16 to 20 ounces and are specifically marketed for use with hot drinks. These are the most common travel mugs, often with quick flip or slide lock lids over the drink opening to protect from basic spills and splash black.
This convenient drink lid is often left open between sips, letting heat escape. To simulate real-world use we evaluated heat retention both with the lid closed (results reflected in the performance graph) and with the drink mouth left open (results not displayed in the graph but used as a second test to investigate the full performance). The size and design of the drink mouth can allow more or less heat to escape and affect the overall insulation performance.
Top Performer
Stanley Classic Trigger-Action Travel Mug
Hot: 6.75 hours
The Stanley Classic Trigger-Action Travel Mug was the standout, lasting almost seven hours before dipping below the 125-degree threshold. That’s enough time to get where you’re going, clear your inbox, and then turn lunch into second breakfast with the warm coffee you’ll still be sipping. Due to the clever design—a push-button “trigger” on the lid needs to be pressed and held to drink from the mug—it’s not possible to accidentally leave the lid open. Though the focus of this test was on insulation performance, we should note that it felt somewhat awkward and uncomfortable to engage the trigger so you can drink. Insulation was outstanding, but the ergonomics could be improved. (Note: uses lead soldering in manufacturing.)
Runner Up
We have a tie!
Thermos Alta Series Stainless Tumbler
Hot: 5 hours
Delivering consistent performance, the Thermos Alta Series impressively recorded the same heat-retention time in both the closed- and open-lid tests. Based on our lab results you can rely on it to keep your drink hot for five hours regardless of whether you leave the lid open for constant sipping or not. This gives it a slight edge over Yeti as second-best overall in the category.
Yeti Rambler
Hot: 5 hours
The Yeti Rambler offered five hours of heat retention with the MagSlider magnetic lid closed. This above-average performance, however, was cut in half when the slider was left open, only staying hot for two and a half hours. The MagSlider lid can be difficult to operate at first (you need to press down on the front of the slider to unlock the magnet before sliding to open) but once you learn the trick it’s easy to open and close with one hand to ensure your drink stays hot. Based on our testing, this well-built mug is a great option when used properly. (Note: uses lead soldering in manufacturing.)
Rest of the Test
All of the travel mugs offered enough insulation to get you through normal commutes to the ski hill, trailhead, or office without letting your coffee go cold. A few other tumblers surprised by performing just as well with the lid open as closed. We chalk this up to the size of the drink opening and thickness of the lid, but did not dig deeper to find out.
Simple Modern Voyager with Flip Lid
Hot: 4.5 hours
This mug had solid overall performance with an easy to use flip lid from a pocket-friendly brand. But you must keep the drink lid closed for optimum performance; in our lab test the rating dropped to two and a half hours with the lid left open.
Corkcicle Classic Tumbler
Hot: 4 hours
The Corkcicle tumbler had consistent performance whether we left the lid open or slid it closed between sips. It also offers the most options for color, pattern, and graphic designs of any mug in the test so you can customize to match your personal style.
Klean Kanteen Rise Tumbler
Hot: 4 hours
The flip lid exposes a large drink mouth that is easy to drink from but lets heat escape easily when left open. Due to the size of the drink opening, it’s also best used when not on the move to avoid spills.
Miir Tumbler
Hot: 3.5 hours
The Miir had strong performance for a tumbler with a simple design. It’s designed to fit securely in car cup holders to make commutes easier. (Note: uses lead soldering in manufacturing.)
Hydro Flask All Around Tumbler
Hot: 3 hours
Scoring the lowest on our insulation performance test, this tumbler will still keep your drink warm longer than a standard ceramic coffee mugwithout a lid, and has a comfortable ergonomic design.
Leak-Proof Travel Mugs
When you’re headed further afield it’s key to ensure your coffee stays secure and hot under more extreme circumstances. These bottles/mugs are purpose-built with leak-proof, drink-through lids that offer access without the need to remove the top. To replicate a cold morning spent outdoors exploring, we set the mugs in a refrigerator with a controlled temp of 39 degrees Fahrenheit. While not extreme, this is a good representation of the average exposure when considering residual insulation from being in a pack.
Top Performer
Thermos Stainless Steel Direct Drink
Room Temperature Test: 11 hours hot || Cold Test: 8 hours hot
The Thermos Stainless Steel Direct Drink bottle was the best overall in the category with its eight-hour insulating performance in the cold environment matching the room temperature results of the next best options. When in milder temps or indoors you can expect your drink to stay hot for up to 11 hours. The bottle has a flip lid that locks in place with a small clip to keep it securely closed without fear of accidentally opening, making it a great option to throw in a pack and forget until you need a pick-me-up on those all-day outings.
Runner Up
Yeti Rambler Hot Shot
Room Temperature Test: 8 hours hot || Cold Test: 6.5 hours hot
With performance ranging from eight hours at room temperature to six and a half hours in the refrigerated cold environment, this bottle is a great on-the-go choice. Its double wall vacuum insulation performed well in our lab tests, and the twist lock drink lid is a unique design solution that conveniently allows sipping from all sides. The lid doesn’t offer any visual clues for when it’s open or closed, so make sure you check before throwing it in your bag. We didn’t do any durability testing, but the Yeti felt sturdy in hand, inspiring confidence for outdoor adventures. (Note: uses lead soldering in manufacturing.)
Honorable Mentions
Miir 360 Traveler
Room Temperature Test: 8 hours hot || Cold Test: 6 hours hot
Matching the Yeti’s performance in the room temperature test, and coming very close (just 30 minutes short) in the cold environment, the 360 Traveler from Miir earns an honorable mention. A unique lid design uses a top push-button that provides 360 degrees of access so you can sip from any side of the mug. We suggest carrying this bottle in its own pocket, like the side mesh on your pack, to keep the push top from being opened by other items while on the move. (Note: uses lead soldering in manufacturing.)
Simple Modern Kona with Locking Flip Lid
Room Temperature Test: 8 hours hot || Cold Test: 6 hours hot
Budget friendly Simple Modern’s Insulated Thermos tested equally as well in both environments as the Miir mug, and nearly as well as the Yeti. The impressive performance comes at a cost $10 below the competition and features a similar lid to the top-performing Thermos. This is a great option to keep your drink hot for six to eight hours.
Rest of the Test
The remaining products provided good, if not quite as long, insulation performance and all passed the leak-proof test, letting you travel without worry.
Klean Kanteen TKWide Coffee Tumbler
Room Temperature Test: 7 hours hot || Cold Test: 6 hours hot
ThisKlean Kanteen mug had consistent performance regardless of the environment in our testing. The flip up carry loop on the lid offers the ability to use a carabiner to clip the bottle wherever you want.
Thermos Stainless King Tumbler
Room Temperature Test: 7 hours hot || Cold Test: 6 hours hot
Dependable performance regardless of the environment, matching the Klean Kanteen in our testing. It’s a more traditional mug styling with a secure slide-switch lid that includes a built-in tea hook.
Stanley Aerolight Transit
Room Temperature Test: 7 hours hot || Cold Test: 5 hours hot
The Stanley provides just enough insulation for quick day missions in the winter, or slow morning summits in the summer. Flip lid snaps securely in place and won’t open easily when getting tossed around or crammed in a bag. (Note: uses lead soldering in manufacturing.)
Hydro Flask Coffee with Flex Sip Lid
Room Temperature Test: 6 hours hot || Cold Test: 4.5 hours hot
This mug has reasonable insulation for this category, but doesn’t hold up as well when exposed to cold environments for a long period of time. It’s better than a tumbler, but only by a bit in cold temps.
Corkcicle Commuter Cup
Room Temperature Test: 3.5 hours hot || Cold Test: 4 hours hot
The Corkcicle Commuter Cup has a design closer to a tumbler, which explains the lower heat retention than other products in the group. We have no explanation for the better (half hour longer) performance in the cold.
Large Thermoses
The classic thermos has a large capacity (25+ ounces) with an extended insulation time rating and typically comes with a cup lid, so the liquid insideis meant to be poured out before being consumed. These bottles are great for carrying drinks (or other hot liquids like soups) to base camp to share, on long hikes that end with a picnic, and during overnights where you want to reduce early morning tasks by brewing in advance.
Since thermoses are used similarly to leak-proof travel mugs—keeping what’s inside hot while its surrounding environment is cold—we tested them in the same controlled refrigerator. The tests differed, however, in the starting temperature. We started the liquid in the thermoses at 180 degrees Fahrenheit, which is the low end of finished brewing temp, since these bottles are designed for transporting but not direct drinking.
Note that not all of the brands in this test have a product that meets the criteria for this category. At the time of testing we didn’t find products from Yeti, Hydro Flask, or Corkcicle that classify as thermoses.
Top Performer
Thermos Stainless King Beverage Bottle
Room Temperature Test: 40.5 hours hot || Cold Test: 33 hours hot
The long-lasting performance of the Thermos Stainless King Beverage Bottle stood out as the most impressive result of all our testing. This bottle kept the beverage warm for 33 hours in the cold environment and for 40 hours when at room temperature.
We initially took temperature readings every six hours, and then checked it more frequently as the water cooled and approached the end of the test. When the Thermos brand bottle was still going strong at the end of day two, there came the harsh realization that a very early morning was in store for the lab techs. In the end, a 2:00 am wake-up call was required to record the final hours.
The Thermos Stainless King’s top-tier insulation is accompanied by classic thermos styling, with a side carry handle, twist and pour stopper, and cup lid to enjoy each serving without bringing a separate mug—pure camping nostalgia.
Runner Up
Stanley Classic Legendary Bottle
Room Temperature Test: 30 hours hot || Cold Test: 24.5 hours hot
Test results showed that you can count on coffee to still be hot in the Stanley Classic after 24 to 30 hours, depending on the weather. These results are more impressive considering how long Stanley has been making this product—though it has had some modern updates through the years, the style and main body remain relatively the same since 1913. Similar to the top performer, this classic bottle comes with a twist and pour stopper, side carry handle, and cup lid to help you transport and enjoy any drink with ease. (Note: uses lead soldering in manufacturing.)
Rest of the Test
Our results showed that every large thermos on test provided enough heat retention to keep their contents hot until the end of a long day (or night) but not all are as capable of making it to day two.The remaining are great options if you’re more confident in the weather conditions and length of your adventure. Equally important, as soup spilled in your bag can quickly ruin a trip, every bottle was leak-proof no matter how hard we shook them.
Klean Kanteen TKPro Insulated Bottle
Room Temperature Test: 26 hours hot || Cold Test: 24 hours hot
With impressively reliable performance in all environments, you can trust this bottle for a true full-day outing, no matter the season. A pour-through stopper and double-wall cup lid are included to make enjoying a drink easy.
Simple Modern Roam
Room Temperature Test: 26 hours hot || Cold Test: 19 hours hot
This bottle’s clever design offers something most competitors don’t: two drinking cups stored directly on the bottle. However, the carry handle is fixed and doesn’t collapse for ease of stowing in a pack. Insulation suffers comparatively at colder temperatures, but still preserved hot beverages for 19 hours.
Stanley Forge Thermal Bottle
Room Temperature Test: 22 hours hot || Cold Test: 18 hours hot
This updated version of the classic Stanley is made with heavy-gauge cold-rolled steel to increase durability. Heat retention is good for the category—though far less than its Classic sibling—without a large penalty when the surrounding environment turns frosty. (Note: uses lead soldering in manufacturing.)
Klean Kanteen Classic Insulated Bottle
Room Temperature Test: 21 hours hot || Cold Test: 15 hours hot
Not technically a thermos (no cup lid or pour top), the claimed thermal properties of this insulated water bottle warranted inclusion in our test. Performance was average and took a big hit in cold temperatures compared to its room-temperature baseline. We’d lean towards three-season excursions with this bottle.
Miir Tomo
Room Temperature Test: 18 hours hot || Cold Test: 12 hours hot
The Miir’s performance is good enough to get through a long day out, but may not last overnight. This sleek bottle comes with two cups, like the Simple Modern bottle, to make sharing with a friend easy. (Note: uses lead in manufacturing.)
Final Thoughts
Across all three categories, one of the longest running names in the insulated mug space, Thermos, consistently performed at the top, despite the significant growth in competition over the last decade. It’s an impressive run for a brand that has been around since the beginning; they produced their first stainless steel vacuum insulated bottle in 1966.
Klean Kanteen, one of the newer competitors, offers products with solid heat retention performance while also being environmentally responsible: they’re climate neutral, a Certified B Corporation, and a member of 1% for the Planet.
Budget friendly options can be seen popping up at big box stores like Walmart and online retailers. One of those brands, Simple Modern, offered good insulation performance when used at room temperature. We found a noticeable decline anytime the products were introduced to a cold environment, but the price and thoughtful designs make them worth consideration, especially if you spend most of your time in milder climes.
Important note: The lab found no performance benefits from the different styles of manufacturing used to seal the insulation layers. Products that use lead soldering performed at both the top and bottom in all categories.