Thermos Stainless King Food Jar Review

We purchased the Thermos Stainless King Food Jar so our expert reviewer could put it to the test. Keep reading for our full product review.

Buying lunch at work every day can get expensive, which is why lots of people opt to pack a brown bag lunch instead. If you don’t have access to a microwave (or don’t like the taste of reheated food), you’ll need an insulated thermos to keep your food at the proper temperature. Thermos is the leading brand in such containers, so we decided to try out its Stainless King Food Jar. The 16-ounce thermos is capable of keeping food hot or cold for hours at a time, plus it comes with a full-size stainless steel spoon and a lid that doubles as a bowl. Not sure if the thermos is for you? Keep reading for our take. 

Design: Some smart design elements 

Of the various insulated thermoses we’ve tested, the Stainless King is our clear-cut favorite. The 16-ounce heavy-duty container is more than just an insulated jar—it also comes with a fold-out stainless steel spoon and its lid doubles as a bowl for added functionality. We love these extra touches as they’re not only easier to use than standard single-use plastic spoons and bowls, but they’re also significantly more eco-friendly.  

The jar’s 16-ounce capacity is ideal for lunch-sized servings of whatever it is you like to eat, be it piping-hot spaghetti and meatballs or a refreshing gazpacho. Plus, the container's 3.7 x 3.7 x 5.5-inch build isn’t too cumbersome if you’re throwing it in a purse or backpack.  

The one design element we would change is the stainless steel lid. While it’s sleek and attractive, it’s also prone to smudges and fingerprints. We’ve tried a few other Thermos-branded containers which are outfitted with ergonomic rubber-gripped lids and we much prefer those. While they’re made mostly for children, they are much easier to twist off—especially if you have wet hands. 

Material: This cup can take a beating

The Stainless King Food Jar is exceptionally durable. The rugged stainless steel container can handle being bumped around in the backseat of a car or jostled about in a backpack during a subway commute. 

The thermos is available in four shades: red, silver, black, and midnight blue. We went with the latter and found that the color didn’t chip when dropped or tossed in a gym bag. The thermos also has a BPA-free plastic gasket which ensures a tight, leakproof seal. Even when filled with liquid and thrown in a backpack, we had no issues with leakage.

Heating Capacity: Delivers on its promises 

Thermos’ Stainless King Food Jar promises 9 hours of warmth and 14 hours of cold. To see what the container was actually capable of, we ran two tests. But before we jump into that, let’s first touch on how Thermos containers are insulated. Basically, the jars have two stainless steel walls and between them is a super-thin layer of empty space. This vacuum prevents heat from entering or leaving the container, which ensures your food stays at its proper temperature. 

Now, for our tests. First, we filled the thermos with freshly made mac and cheese. Every hour on the hour, we checked in to take a bite and see if the temperature had decreased. Without fail, we found our food nice and warm each time we went in for a taste. Finally, the temperature began to fall around 9 hours in—which was exactly what the brand had promised. After our test, we were confident that the container would work well for soups and other foods that are even hotter to begin with.  

As we expected, the insulative properties of the thermos worked superbly with cold liquids as well. Our ice water still had ice cubes floating in it more than 14 hours later, again meeting the promised time for keeping liquids cool.

Care: Fine for most office workers

While Thermos’ product listing says it’s safe to wash the Stainless King on the top rack of a dishwasher, the company does say handwashing is preferred. This is because the thermos is comprised of multiple pieces (a lid, spoon, gasket, and jar) which need to be separated and because hot water and harsh detergents can damage the container’s exterior. 

Luckily, since the thermos has such a wide mouth, cleaning it by hand isn’t so bad. It’s easy to fit a sponge or cleaning wand inside and when it comes to the lid and gasket, you just need to make sure you take the pieces apart. 

While washing the container by hand may be annoying for some, we actually don't think it'll be a big deal for office workers who’re already used to rinsing their dishes in a communal sink. In our testing, it took no more than a minute to fully clean. 

Price: Reasonable 

At $25, the Stainless King Food Jar is pricier than other thermoses we’ve used, but it’s also much bigger and comes with extra accessories. Compared to other leading brands like YETI, S’well, and Zojirushi, it’s also a really good deal. 

Competition: A whole catalog of options 

Thermos FUNtainer Stainless Steel Food Jar: When comparing solely the length of time these two thermoses can keep food warm, the Stainless King easily wins. The FUNtainer does serve another distinct purpose, though. The small, 10-ounce thermos is ideal for kids with a grippy lid, themed Disney designs, and smaller build that’s a better fit for small hands. It’s also $10 cheaper than its larger sibling, so if your kid misplaces it on the bus, it won’t hurt your wallet quite as much. 

Thermos Foogo Stainless Steel Food Jar: Like the Stainless King, the Foogo Food Jar uses double-walled, vacuum-sealed technology to keep its contents at the correct temperature. For this reason, we were surprised to find that the Stainless King provided many more hours of warmth. If you’re shopping for an adult thermos, the Stainless King is our go-to, but if you’re looking for kids, the Foogo may be a better choice. The latter comes in a variety of fun colors and its smaller at 10 ounces.