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Whether your hot beverage of choice is coffee, tea, or matcha, you’ve likely adopted a favorite travel mug to carry your magical morning elixir to the office or the trailhead. But do you know how its performance stacks up against the competition? Instead of relying on haphazard observations and product claims, the �����ԹϺ��� Lab @ CU Denver set up an experiment to find out which travel mugs are the best at keeping beverages warm.

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 38 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.

Updated May 2025: We added six new tumblers, six new travel mugs, and three new thermoses to the �����ԹϺ��� Lab testing groups, and highlighted some new top performers based on results. We also updated info and pricing on previously included mugs/bottles.

At a Glance

• What the �����ԹϺ��� Lab Tested
• How We Tested Mugs at the �����ԹϺ��� Lab
• Spill-Proof Tumblers
  • Top Performer:
  • Runner Up: 
  • Honorable Mentions
  • Rest of the Test
• Leak-Proof Travel Mugs
  • Top Performer:
  • Runner Up:
  • Honorable Mentions
  • Rest of the Test
• Large Thermoses
  • Top Performer:
  • Runner Up:
  • Honorable Mentions
  • Rest of the Test
• Final Thoughts

What the �����ԹϺ��� Lab Tested

We selected popular models of the three most common types of insulated travel mugs and bottles specific to hot drinks.

1. Spill-Proof Tumblers: Mugs with lids that typically slide or flip open
2. Leak-Proof Travel Mugs: Bottles with a fully sealed “drink through” lid that can be thrown in a bag without leaking
3. 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 focused our efforts on heat retention performance, and did not test for lead. Check with the brand for their current process.

How We Tested Coffee Mugs at the �����ԹϺ��� 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 lets 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 during commutes 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.

Best 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.

Best in Test

Zojirushi Stainless Tumbler SX-FSE45

Heat retention shined on this tumbler that kept drinks hot for five and half hours with the spill-proof lid closed. Performance did suffer when the lid was left open, but the beverage still stayed warm for more than three hours. The twist-close lid is easy to use, protects from spills, and comes with a removable stainless steel tea leaf strainer that attaches to the underside for those who want to brew their leaves on the go. The Zojirushi’s relatively small package and classic shape works well with cup holders.

Runner Up

Contigo Streeterville Stainless Steel Mug

Hot: 5.25 hours

This tumbler delivered good heat retention with its slide lid closed, and was equally impressive when the lid was left open in the drink position. Keeping drinks hot for at least five hours in both scenarios gives confidence when using this Contigo mug during long mornings. The slide lid doesn’t lock but is easy to use one handed, and the mug has a non-slip rubber base for added desk security.

Honorable Mentions

All of the 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 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.

Thermos Alta Series Stainless Tumbler

Hot: 5 hours

Delivering consistent performance, the Thermos Alta Series impressively recorded the same failure 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 even if you leave the lid open for constant sipping.

Ello Campy

Hot: 5 hours

Our testing showed that the Ello Campy can be trusted to keep your drink hot for up to five hours, matching other top performers in the category. It has the added benefit of a cork inlay handle that is comfortable to hold and is set higher on the mug to fit most cup holders, which gives it a classic look. The slide lock lid opens and snaps closed easily with one finger to keep spills at bay.

Yeti Rambler Travel Mug

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 locks in place and does not move unless intentionally pushed, which helps prevent spills and heat loss. Based on our testing, this well-built mug is a great option when used properly.

Rest of the Test

• 
  Hot: 4.5 hours
• 
  Hot: 4.5 hours
• 
  Hot: 4.5 hours
• 
  Hot: 4 hours
• 
  Hot: 4 hours
• 
  Hot: 3.75 hours
• 
  Hot: 3.5 hours
• 
  Hot: 3 hours

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.

Best in Test

Zojirushi Stainless Mug SM-SF48

With category-leading heat retention performance, the Zojirushi Stainless Mug SM-SF48 proved that it can keep your drink hot during long adventures no matter the environment. You can trust your coffee or tea to still be hot after half a day when in pleasant temperatures, and up to nine hours when out in the winter cold. The flip-top lid is easy to open with the push of a button. A small slide lever next to the push-button allows you to lock the lid closed to prevent accidents when on the go. The size is surprisingly svelte for the 16-ounce capacity and this level of insulation performance. Combined with the locking lid, this bottle is perfect for throwing in a pack and hitting the trail (or skintrack).

Runner Up

Thermos Stainless Steel Direct Drink

The Thermos Stainless Steel Direct Drink bottle was a close second in the category. When indoors or out in milder temps you can expect your drink to stay hot for up to 11 hours. If venturing out in the cold, you can trust the Thermos to keep beverages warm for eight hours, matching the room temperature performance of the next best options. 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.

Honorable Mentions

The remaining products provided good, if not quite as long, insulation performance and all passed the leak-proof test, letting you travel without worry.

Yeti Rambler Hot Shot

With heat-retention performance ranging from eight hours at room temperature to six and a half hours in the refrigerated cold environment, this bottle is a great choice for on-the-go needs. The unique twist-lock drink lid conveniently allows sipping from all sides (though it doesn’t offer any visual clues for when open or closed). The mug’s sturdy feel inspires confidence for outdoor adventures.

Miir 360 Traveler

Keeping drinks hot for eight hours when at room temperature, and six hours in the cold, the 360 Traveler from Miir earns an honorable mention. Adding to its appeal is a unique lid design that uses a top “push-button” to provide, as the name states, 360 degrees of drink access. We suggest carrying this bottle in its own pocket, like the side mesh on your pack, to keep the push top from being accidentally opened.

Simple Modern Kona w/ Locking Flip Lid

Budget-friendly Simple Modern’s Kona travel mug tested equally as well in both environments as the Miir mug, and nearly as well as the Yeti. The mug delivers this impressive performance—drinks stay hot for six to eight hours—at a cost $10 below the competition. An easy-to-use lockable flip lid ensures your drink stays secure no matter where the mug is stored or how much it gets tossed.

Rest of the Test

• 
  Room Temperature Test: 7 hours hot
  Cold Test: 6 hours hot
• 
  Room Temperature Test: 7 hours hot
  Cold Test: 6 hours hot
• 
  Room Temperature Test: 7.25 hours hot
  Cold Test: 5.5 hours hot
• 
  Room Temperature Test: 7 hours hot
  Cold Test: 5 hours hot
• 
  Room Temperature Test: 6 hours hot
  Cold Test: 4.5 hours hot
• 
  Room Temperature Test: 6 hours hot
  Cold Test: 4.5 hours hot
• 
  Room Temperature Test: 3.5 hours hot
  Cold Test: 4 hours hot
• 
  Room Temperature Test: 4.25 hours hot
  Cold Test: 3.25 hours hot
• 
  Room Temperature Test: 4 hours hot
  Cold Test: 3 hours hot
• 
  Room Temperature Test: 4 hours hot
  Cold Test: 3 hours hot

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 inside is 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.

Large thermoses during testing. All bottles were marked with their start time and had an individual alarm set for each temperature recording. Thermometer used to monitor the room temperature for the duration of the test can be seen at the top of the image. (Photo: Adam Trenkamp)

Since thermoses are used similarly to leak-proof travel mugs—keeping what’s inside hot while the 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.

Best in Test

Thermos Stainless King Beverage Bottle

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

Zojirushi Stainless Bottle SJ-JS10

With a 35-ounce capacity and all-day performance, you can take the Zojirushi JS-10 vacuum insulated thermos on overnighters to help kickstart morning camp for two to four people—or keep it to yourself to pour fresh cups from it all day. Heat retention was recorded as over 24 hours, even in the cold. In warmer climes, you can expect liquids to stay hot for up to 31 and a half hours.

The bottle comes with a cup lid and a unique pour-through stopper that opens with a simple one-touch button that’s different from any design we’ve seen previously. This setup reduces heat loss when open and helps to control the flow when pouring. Removing the screw-on stopper reveals a wide opening that makes cleaning and refilling easy.

Honorable Mentions

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.

Stanley Classic Legendary Bottle

Room Temperature Test: 30 hours hot
Cold Test: 24.5 hours hot

Test results are impressive considering how long Stanley has been making this product—though it has had some modern updates through the years, the style has remained relatively the same since 1913. This classic bottle (as the name implies) comes with a twist and pour stopper, side carry handle, and cup lid to help you transport and enjoy any drink with ease.

Ello Therma Insulated Thermos

Room Temperature Test: 31.5 hours hot
Cold Test: 24 hours hot

This thermos provides top-notch performance in a simple, convenient design regardless of the weather on your outdoor excursion. Drinks will still be hot even after 24 hours of the bottle being exposed to the cold. The aesthetic is classic, but the pour-through stopper with magnetic slider is a nice upgrade to the user experience that makes pouring into a cup easier, reduces spills, and improves heat retention.

Klean Kanteen TK Pro Insulated Bottle

Room Temperature Test: 26 hours hot
Cold Test: 24 hours hot

With impressively consistent performance in all environments you can trust this bottle for a true full-day outing, sunrise to sunrise, no matter the season. A pour-through stopper and double-wall cup lid are included to make enjoying a drink easy whenever you’re ready.

Rest of the Test

• 
  Room Temperature Test: 26 hours hot
  Cold Test: 19 hours hot
• 
  Room Temperature Test: 22 hours hot
  Cold Test: 18 hours hot
• 
  Room Temperature Test: 21 hours hot
  Cold Test: 15 hours hot
• 
  Room Temperature Test: 18 hours hot
  Cold Test: 12 hours hot
• 
  Room Temperature Test: 13 hours hot
  Cold Test: 9.5 hours hot

Final Thoughts

Across all three categories, one of the longest-running names in the insulated mug space, Thermos, consistently performed at or near 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. Another standout brand in every category was Zojirushi, a Japanese manufacturer with a history as deep as Thermos and Stanley. Over the last decade, their products have become more widely available and immediately emerged as fan favorites for performance, quality, and clever design features.

Klean Kanteen, a newer brand in the space, 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. Two of these brands, Simple Modern and Contigo, offered good insulation performance and unique designs to rival the big brands at more affordable prices. We found a noticeable decline anytime the products were introduced to a cold environment, but the overall performance, especially if you spend most of your time in milder climes, makes them worth considering.

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