The Best Insulated Thermoses That'll Keep Things Very Hot or Cold

One of our top picks is the GSI Outdoors Glacier Stainless 1 L Vacuum Bottle.

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A group of thermoses sitting on a counter

Serious Eats / Vicky Wasik

Straight to the Point

Our favorite thermoses are the GSI Outdoors Glacier Stainless 1 L Vacuum Bottle and Stanley Legacy Quadvac Thermal Bottle. Both have excellent hot and cold retention and usability features that make them standouts.

Sometimes, while camping, picnicking, or pulling a double-shift, a travel mug just doesn't cut it. That's when you need a larger, sturdier thermos to keep hot drinks hot and cold drinks cold for 8, 12, and even 24-plus hours.

Like travel mugs, thermoses use vacuum-insulated technology (and were originally popularized by the Thermos brand). Basically, it's a bottle within a bottle that has a vacuum between its two walls. And because this vacuum contains no air, it doesn't conduct heat, which allows the contents inside the bottle to stay at the same temperature longer. This double-walled vacuum design also prevents condensation from forming on the outside of the bottle and allows the bottle to stay cool-to-the-touch, even when full of something piping hot.

Now that we've covered why a thermos is great (and how it works), let's talk about the best ones to buy. For this review, we tested nine thermoses, running them through temperature, durability, usability, and cleanup tests.

The Winners, at a Glance

The Best Thermos: GSI Outdoors Glacier Stainless 1 L Vacuum Bottle and Stanley Legacy Quadvac Thermal Bottle

GLACIER STAINLESS 1 L VACUUM BOTTLE
LEGACY QUADVAC™ THERMAL BOTTLE

Sleek and sturdy, the GSI Outdoors Glacier Stainless 1 L Vacuum Bottle kept hot drinks hot and cold drinks cold. A high scorer on all tests, it has a non-slip base and grooves on the outside of the bottle that make it easy to grip.

We also loved the Stanley Quadvac Thermal Bottle. This bottle had excellent hot and cold retention and has a removable handle wrap that makes it a cinch to carry.

The Best Thermos For Everyday Use: Zojirushi Stainless Bottle SJ-JS10 and SJ-TG08/10

Stainless Bottle SJ-JS10
Stainless Bottle SJ-TG08/10

If you want a smaller daily thermos that melds both form and function, both the Zojirushi Stainless Bottle SJ-JS10 and SJ-TG08-/10 are excellent options. The former has cute illustrations on the exterior of the bottle, while the latter is available in 27-ounce and 34-ounce sizes and features an adjustable carrying strap.

The Criteria: What to Look For in a Thermos

four of our favorite thermoses beside one another on a countertop

Serious Eats / Vicky Wasik

What Is It?

A thermos is a vacuum insulated bottle that keeps liquids hot or cold for an extended period of time. Unlike a travel mug (which you drink out of), thermoses usually feature a lid that you remove and pour liquid from the thermos into, so it doubles as a cup. And while travel mugs have, on average, a 16-ounce capacity, thermoses are much bigger. The thermoses we tested were anywhere from 32 to 42 ounces, which is about 1 liter.

What Makes a Good Thermos?

A good thermos should have excellent hot and cold retention. It should never leak, be convenient to use and carry, and be easy to clean, not retaining residual flavors or odors from drink-to-drink. A great thermos should also be able to take a bit of a beating, whether it's tossed around in a backpack or dropped while at a campsite. Plus, if it looks nice, that's all the better.

How We Picked the Products in the Review

When setting out to find the best thermoses, we started out by looking at the offerings from recognizable brands (Zojirushi, Thermos, Stanley). We also looked at the highest-rated thermoses sold on Amazon, as well as specialty retailers like REI. We made sure to review what other experts have said about thermoses, examining sites like Wirecutter and Popular Mechanics.

Why You Should Trust Us

Kathleen Squires has been an expert user of thermoses since grade school, beginning with her very first Planet of the Apes lunchbox. But seriously, as an avid home cook and someone who has written professionally about food for over two decades—plus as a co-owner of a private event space centered around a kitchen—she takes great care in assessing each and every piece of equipment she purchases and uses (thermoses included).

The Testing

A Thermapen measuring the cold retention of a thermos

Serious Eats / Vicky Wasik

Kathleen Squires has spent more time with these nine thermoses than with her family recently, examining the bottles' hot and cold retention, seals, durability, and how easy they were to clean and use.

Test 1: Cold Retention and Ice Test

a chart tracking the cold retention of the thermoses after six hours and overnight

Serious Eats / Amelia Manley

Each bottle was filled with 36°F ice water (four degrees shy of water's freezing temperature), and the temperature was noted with a calibrated instant-read thermometer. The temperature was checked every 30 minutes for 6 hours, and then the bottles were left overnight before temping them again every hour the next day until the water reached 60°F—eight degrees shy of room temperature. Any models that warmed up quickly were noted.

After their overnight stint, only five of the bottles were below 50°F. And after 48 hours, only three brands remained under 60°F: Thermos (53.2°F); GSI (56.5°F); and Stanley Quadvac (58.6°F).

Test 2: Heat Retention and Leakiness

coffee being poured into a thermos

Serious Eats / Vicky Wasik

Two heat retention tests were run. For the first, each bottle was filled with boiling (212°F) water, then the temperature was tested with a calibrated instant-read thermometer every 30 minutes for 7 hours before leaving the bottles overnight and testing them again every hour the next day until the temperature fell to 140°F (which, granted, is still very hot). During the first test, the bottles were laid on their sides on a towel to test for leaks. For the second heat retention test, each bottle was filled with 184°F coffee, then left the filled thermoses for 18 hours. This was done to see how the bottles would perform without constant opening and closing.

And, indeed, there were big differences in heat retention. The model from Hydro Flask brought boiling water down to 140°F after only 4.5 hours and coffee was at 105°F after 18 hours, which is tepid. The best models kept boiling water around 136 to 150°F after 24 hours and coffee at 143 to 152°F, dropping just 32 to 41 degrees.

Unlike the heat retention tests, the leaking test was rather inconsequential—with the exception of one model. The Otterbox thermos leaked immediately and, when the top was removed and put back on it to make sure it was screwed on correctly, its top popped off the bottle, sending scalding hot water all over the towel and onto the floor.

Test 3: Washing

After leaving the coffee to sit in the bottles, those that were dishwasher-safe were placed in the dishwasher, and those that were not were hand-washed. All dishwasher-safe bottles emerged unscathed, and all hand-washed bottles were easy to clean, especially when using a bottle brush. After washing, any residual stains inside the bottle or on its parts were noted.

None of the bottles were stained nor had any noticeable odors or flavors. However, the removable parts of all of the models—the stoppers and lids in particular—did have a residual coffee odor, which was remedied by soaking the parts in hot soapy water for an hour and then rinsing.

Test 4: Usability

coffee being poured from a zojirushi thermos

Serious Eats / Vicky Wasik

The biggest question when using a thermos is, first and foremost, if they're easy to pour and drink from. The best models were not too heavy and were easy to lift, pour from, and hold onto. They also had deep cups that were comfortable to hold and drink from.

Other items considered were whether the thermoses had any helpful accessories, like a carrying strap, a non-slip base, or grooves on the sides of the bottle that provided extra grip.

Test 5: Durability

To test durability, each thermos was filled, sealed, then dropped them from five feet onto the floor at three different angles so that the thermoses would hit the ground on their top, bottom, and side. After the tests, all the models were examined for dents, dings, scratches, leaks, crack. All received minor scratches and dents, but two models dented horribly and began to leak.

The Best Thermos: GSI Outdoors Glacier Stainless 1 L Vacuum Bottle

GLACIER STAINLESS 1 L VACUUM BOTTLE

What we liked: This model from GSI Outdoors is super sturdy, sleekly designed, and easy to carry and use. It had excellent cold and heat retention, too. Though the manufacturer recommends that it be "primed," which means filling it with cold water and letting it stand for 5 minutes before cold use, this wasn't necessary when testing. It was easy to pour from and had a deep cup that was great to hold and drink from. The grooves on the outside of this thermos made it easy to grip, it had a non-slip base, and it suffered minimal damage after being repeatedly dropped. Plus, it comes in five colors and has a lifetime warranty.

What we didn't like: Not much—this is a great all-around thermos.

Key Specs

  • Capacity: 33.8 fluid ounces
  • Materials: Stainless steel; plastic
  • Cleaning: Dishwasher-safe but brand recommends hand-washing
GSI Outdoors thermos on countertop

Serious Eats / Vicky Wasik

Another Great Thermos: Stanley Legacy Quadvac Thermal Bottle

LEGACY QUADVAC™ THERMAL BOTTLE

What we liked: This thermal bottle had a handy (pun intended) removable carrying sleeve, sturdy design, and deep cup that was great to drink from. It had excellent heat and cold retention, too, and was easy to carry thanks to its handle. It's available in three colors and is dishwasher-safe for those that find that to be a dealbreaker.

What we didn't like: It was the heaviest of the bunch at 1 pound 14.4 ounces, making it a touch harder to pour from.

Key Specs

  • Capacity: 35 fluid ounces
  • Materials: Aluminum
  • Cleaning: Dishwasher-safe
Stanley thermos on countertop

Serious Eats / Vicky Wasik

The Best Thermos For Everyday Use: Zojirushi Stainless Bottle SJ-JS10

Stainless Bottle SJ-JS10

What we liked: Well-designed, this thermos seemed smaller than the competition. However, it still held a liter of liquid despite also being one of the lightest weight models. It excelled at heat and cold retention, too, but particularly at the former, where it was at the top of the pack. It had a unique push-button spout top that works well for pouring and came with a fairly deep cup that's comfortable to drink from. While it's not dishwasher-safe, this thermos is incredibly sturdy and incurred the least damage after being repeatedly dropped. It comes with a 5-year warranty as well.

What we didn't like: If you want a thermos that's dishwasher-safe, this isn't the model for you.

Key Specs

  • Capacity: 35 fluid ounces
  • Materials: Stainless steel
  • Cleaning: Hand-wash only; not dishwasher-safe
Zojirushi thermos on countertop

Serious Eats / Vicky Wasik

Another Great Everyday Thermos: Zojirushi Stainless Bottle SJ-TG08/10

Stainless Bottle SJ-TG08/10

What we liked: The Zojirushi SJ-TG08/10 performed excellently, too. Like the other Zojirushi model, it was smaller and lighter weight than other models but still had a sizable capacity (it comes in a 27-ounce size as well, for those looking for a smaller thermos). It didn't perform as well as the above models in the heat retention tests (it still did admirably) but excelled at cold retention. It was incredibly durable and, like the other Zojirushi model, sustained little damage after being repeatedly dropped. It was easy to pour from and came with a cup that satisfyingly "snaps" into place when secured onto the thermos. It has a handy adjustable carrying strap and comes with a 5-year warranty.

What we didn't like: If you're going to be using a thermos solely for hot items, this isn't our top pick.

Key Specs

  • Capacity: Comes in 27 and 34 fluid ounce sizes
  • Materials: Stainless steel
  • Cleaning: NA
Zojirushi thermos on countertop

Serious Eats / Vicky Wasik

The Competition

  • Thermos Stainless King Beverage Bottle: This thermos had excellent heat and cold retention and performed incredibly well...until it got to the durability test. After it was dropped, it dented so much that it leaked and its lid would no longer unscrew from the base. That said, if you don't plan on dropping it, at just $21, it's a solid model for the price.
  • Stanley Classic Legendary: This is a solid all-around thermos, but it just didn't have as good hot or cold retention as the top models.
  • Otterbox Rugged Mini Growler: Besides lacking adequate hot or cold retention, this model leaked, and its cap popped off of it during the boiling water test. The bottle's top also came off after being dropped, and it's incredibly expensive, at about $80.
  • Hydro Flask 32 oz Wide Mouth with Straw Lid: While this model was easy to drink from (with a flip-spout), it had poor heat and cold retention.
  • Swell 40z. Onyx Roamer: This thermos also had poor heat and cold retention and was bulky, heavy, and therefore hard to carry.

FAQs

Are thermoses dishwasher-safe?

Whether or not a thermos is dishwasher-safe varies from model to model. One of our favorite thermoses, this model from Stanley, notes it's dishwasher-safe. However, a lot of manufacturers do not state whether or not their thermoses are safe to clean in the dishwasher. When in doubt, hand-washing a thermos is always the best bet (with travel mugs, cleaning it in the dishwasher can result in water getting in between the layers of insulation, thus damaging it).

Which thermos keeps things hot the longest?

After our tests, the Zojirushi SJ-JS10 had the best heat retention, with the Stanley Legacy Quadvac Thermal Bottle and GSI Outdoors Glacier Stainless 1 L Vacuum Bottle not far behind it.

Which thermos keeps things cold the longest?

We found the Zojirushi Stainless Bottle SJ-JS10, Stanley Legacy Quadvac Thermal Bottle, GSI Outdoors Glacier Stainless 1 L Vacuum Bottle, Zojirushi Stainless Bottle SJ-TG08-/10, and the Thermos Stainless King Beverage Bottle all had excellent cold retention.

What's the difference between a thermos and a travel mug?

A thermos is much larger than a travel mug, and while a travel mug is meant to be sipped directly from, a thermos is usually meant to be poured from and comes with a detachable lid that doubles as a cup.