The Ultimate Water Bottle Insulation Test (Over 30 Bottles, Hot & Cold!)

5/7/2025

Which Water Bottle has the Best Insulation?

(10 minute read)

Which Water Bottle has the Best Insulation?

Which bottles have the best insulation, and do they really live up to their claims to keep drinks cold for 24 hours or hot for 12? We tested over 30 bottles, including both hot and cold tests to see how the results compared, and we're posting all the juicy details below for your over-analyzing pleasure.

So if you're looking for the absolute best water bottle for either hot or cold drinks, this post is for you.

Let's get started!

Sneak Peek Summary

Here are the best and worst 3 for both the hot and cold tests (click the links to see them on Amazon).

Hot Test, Best 3

1) S'well (Original 25oz)
2) Stanley Thermos (1L)
3) RevoMax (20oz)

Hot Test, Worst 3

30) Stanley Quencher (40oz)
31) Hydro Flask Tumbler (40oz)
32) Brumate Era Tumbler (40oz)

Cold Test, Best 3

1) Stanley Thermos (1L)
2) Camelbak Chute Mag (32oz)
3) S'well (Original 25oz)

Cold Test, Worst 3

30) Hydro Flask Tumbler (40oz)
31) Stanley Quencher (40oz)
32) Zulu Ace (24oz)

Since ice water is the most common way people use these big bottles, here are the bottles listed from best-to-worst based on their cold water test (you'll see the full data a little later). All of these are dual-wall vacuum insulated stainless steel, with the exception of Nalgene (plastic) which was included as a control.

Videos: Insulation Tests

We also covered each test in separate YouTube videos if you'd prefer to watch the recap that way.

Amazon Associates Disclosure
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Which Water Bottle Keeps Drinks the Hottest?

First, let's look at the hot water insulation test. To standardize the test, I bought this set of wireless thermometers. It's the kind that are primarily used for smoking meats and grilling, but it worked well for this purpose too. It comes with these two sensor probes that are individually labeled on top, and they connect wirelessly to a readout display. I wasn't sure how water proof the sensors were, so I made a little float for each one so only the bottom part of the probe would be underwater.

Wireless Thermometer

Floats for Probes

Probe in Bottle

Thermometer Readout and Timer

Wireless Thermometer Set

In case you're curious, here's the thermometer I used. It's pretty slick. The app is useful for setting the target temp and monitoring it remotely, though don't expect much from the table output or being able to export data beyond just a low-res jpg.

But if all you need is to monitor meat on a smoker so you can know when it reaches a certain temperature, these would work great (I'll be doing some of that this summer!).

See Wireless Thermometer

Methodology:

Fill two 16oz plastic measuring cups with tap water
Microwave for ~5.5 minutes (gets the temps to a little over 165 degF with my microwave)
Add water to two bottles
Drop in wireless thermometers and close the lids
Wait for the water to drop below 165 degF, then start a timelapse video with a stopwatch timer next to the thermometer readout
Stop the test when both bottles have reached 150 degF
Watch the timelapse and record the exact moments that the temperatures for each bottle last read 165 degF and first read 150 degF
Pour out the water and wait a few hours with the lids off for the bottle temperatures to equalize
Repeat the test, switching which probe goes in which bottle, then average the results
Repeat all of the above steps for all 30+ bottles

Table of Hot Insulation Test Results

There are a few things to note about this test.

Not for Hot: Some bottles like Owala say they're not meant to be used with hot drinks, but from what I've read, that's usually just a safety concern because they want to prevent situations where pressure may build and someone could get burned. Insulation works similarly for both hot and cold, so these hot tests should still give you good relative ranking for these bottles even if you're planning to buy one for ice water.
Volume vs Capacity: Each bottle had 16oz of water in it regardless of the volume capacity of the bottle. That was to make each bottle start with the same energy/heat in the system, but if you filled the larger bottles to the top with 165 degF water, I would expect they'd stay above 150 degF longer because they started with more overall energy/heat. But honestly I'm not entirely sure what the impact of the different volume would be (open to hearing your thoughts!).
Wireless Signal Issues: For some reason, the wireless thermometers wouldn't reliably transfer the signal through the S'well bottle and Stanley thermos. So instead, I went the old fashioned way and used a candy thermometer. I heated up the water and waited until it was right around 165 degF, then I closed the lid. I guessed how long it would take to drop to 150 and took a measurement. Then I adjusted my guess and repeated it again and again over several iterations. I did it this way because I didn't want there to be any error from removing the lid and checking the water temperature multiples times within a single test.
Checked Thermometers: To make sure the results would be comparable, I tested all the thermometers first and they were pretty much the same.

Which Water Bottle Keeps Drinks the Coldest?

Most people use large water bottles for ice water instead of hot drinks, so I also did a cold water test. For this test, I left the bottles outside so they got some sunlight to simulate if you were using it hiking or at the beach. But because it's a lot harder to predict temperature changes outside compared to inside, I elected to do one big test with all the bottles at the same time while measuring the temperature at the start and end of a 24-hour period.

Bottles on a Table Outside (before filling)

Ice Water in YETI Cooler

Using the Drain as a Strainer

Measuring Ending Temperatures

Methedology:

Lined up all of the bottles on a table outside where sunlight would not vary much based for any particular bottle
Took off all of the lids to make sure each bottle had the same starting temperature
Filled a YETI cooler with ice water
Used the drain as a strainer to fill a bottle, recorded the starting temperature, then closed the lid
Notable, this test involved filling each bottle to the very top to simulate practical real-world use, but it's different than how I did the hot test (16oz of hot water regardless of bottle size)
Repeated for all 30+ bottles
Waited 24 hours
Opened each bottle and recorded an ending temperature, ensuring that the bottles were tested in the same order as they were filled and on the same frequency (a rate of 1 per ~1 minute)
Compared the starting and ending temperatures

Table of Cold Insulation Test Results

There are a few things to note about this test.

Only 1 Test: I only did 1 iteration. Ideally I'd do multiple tests to balance out possible impacts of sunlight, the ice water temperature variability, and the order of the test, but because this test takes so long I haven't had time to do more yet.
Some Odd Results: While these results mostly tracked with the hot test, there were some odd results and notable differences. Some brands like Owala and Camelbak did much better on the cold test than the hot test, while Hydro Flask did much worse. Much of this is likely due to the difference between filling up partially for the hot test and full for the cold test (makes the smaller bottles look better on the hot test). Also, I don't have a good explanation for why Takeya's insulated lid (Actives Series) did so much sorse than their original style lid with the hot water test. These are details I hope to learn more about when I repeat this in the future and have more data to average out possible issues.
Starting Temp: The starting temp of the ice water was higher for the first bottles tested and lower by the end. This is likely because the concentration of ice-to-water increased as the testing went on, leaving the remaining water in the YETI colder. While it was only a few degrees difference, this may have had an impact on the results and made the bottles starting with colder water seem worse if you're measuring based on the 24-hour temperature change. But my hope is that doing it over such a longer period of time negated some of that impact.
Additional Info: I added more columns to this table to give you more practical info, hopefully to help you find the best bottle for your needs and situation.

Conclusions: Which Bottles have the Best Insulation?

Links to each bottle in order from best-to-worst are shown at the beginning under the Sneak Peek Summary, so I won't repeat them here. But after these tests, I came away with four main conclusions in general when it comes to water bottles and insulation.

Conclusion #1: Mouth Diameter is Important

The easiest way to guess a bottle's insulation that's also fairly reliable is the mouth diameter. A good rule of thumb is the wider the opening, the worse the insulation. That makes sense because most heat is lost through the lid, as you can clearly see in thermal imaging between Owala's bottle (narrower) and Owala's newer Sway tumbler (wider opening).

Just don't forget to consider the mouth diameter too if you'd mostly use it with ice water, so think about the size of your ice cubes too.

Thermal Imaging of Owala Sway vs Owala Original

Conclusion #2: Lid Design is Even More Important

While the mouth diameter is the most common factor, the lid design, and specifically if it makes a dual-seal, seems to be the most important factor.

Each of the top three bottles on both tests creates your typical seal at the rim of the bottle that you see in every single bottle on this list, but they also make a second seal on average about an inch or two down the neck of the bottle.

With S'well's lid, this seal presses up against this part of the neck than narrows a little bit more.

Double Seal on S'well

RevoMax has a threadless lid that expands in the neck of the bottle.

Double Seal on RevoMax

The dual seal traps some heat and acts extra insulation insulator. So bottom line, if you look at a bottle and see it's designed to create a dual seal, then odds are it will have really good insulation.

Conclusion #3: Best Big Tumbler (like Stanley Quencher)

If you like a big tumbler with a side-mounted handle, the bad news is that most of them have pretty poor insulation because they have such a wide mouth diameter. But if insulation is important to you and you really like that style bottle, then take a serious look at Simple Modern because they were way better than all the other similar tumblers on this list.

Here's the breakdown if you grouped the bottles by different volumes, and it's really clear just how much better Simple Modern was. Here's the breakdown for the hot test, and it was also by far the best large tumbler in the cold test.

Table of Hot Test Results for 40oz Bottles and Tumblers

Conclusion #4: Popular and Expensive does not Guarantee Better Insulation

Branding and marketing really don't matter much when it comes to insulation. Brands like Owala and Stanley always say they have amazing insulation, and Stanley in particular got a lot of viral attention when a car caught on fire but the Stanley inside survived and still had ice. But that that doesn't mean they have better insulation than any of these other brands, and in fact they have consistently tested worse.

The best example of this is how Ozark Trail costs about $12, and it has the same or even better insulation than many brands 3-4x their cost like YETI and Hydro Flask.

The truth is most bottles with dual-wall vacuum insulation are good enough for most people most days, so instead consider focusing on other buying factors like whether you like the brand, lid design, and if it fits in your cupholder.

Here's our most comprehensive list of bottles yet, including their benefits and drawbacks.