The Best Food Thermos

We’ve added long-term test notes for the Zojirushi Stainless Steel Food Jar.

Whether you’re packing chili for lunch or oatmeal to eat after your morning commute, a great food thermos will keep hot foods at safe temperatures for hours and won't leak into your bag. After comparing 22 food thermoses and testing 10, we’re confident that the Zojirushi Stainless Steel Food Jar is the best for most people. It has excellent heat retention, is durable and easy to clean, and comes in three sizes ranging from 12 to 25 ounces. We like the 10-ounce Thermos Funtainer Food Jar for packing kids’ lunches or for people who prefer smaller portions.

This container keeps food hot for hours and comes apart easily for cleaning.

*At the time of publishing, the price was $30.

Why we love it: In our tests, the Zojirushi Stainless Steel Food Jar was one of the best at keeping soup hot. The 12-ounce thermos kept tomato soup above a food safe temperature (140 °F) for a full 6 hours, dropping from 193 °F to 144 °F. The only thermoses that did better were the 17-ounce Stanley Classic (larger volumes of liquid take longer to cool) and the Black and Blum Food Flask (which has an awkward strap around it). Zojirushi says that its thermos will keep foods at a safe temperature for about 6 hours, and we were glad to see that for liquids, the thermos exceeded the estimate (it will also keep foods cold for 6 hours, although we didn't test for this). I use the Zojirushi Stainless Steel Food Jar multiple times a week to transport my morning green smoothie to work, and I’ve also used it to hold chili, soup, and oatmeal. It continues to keep foods at temperature and it has survived many commutes. Zojirushi's travel mugs have reigned as our top pick for over three years; the company makes the best insulated mugs and thermoses we’ve found.

When shaken or held upside down, the Zojirushi didn't leak (though none of the thermoses we tested did). A screw-on cap is easy to get on and off, and the narrow container fits easily in one hand, unlike the wider and unwieldy Thermos Stainless King or the Stanley Classic. The Zojirushi is also durable, surviving our drop test unscathed. Other metal jars dented upon impact, and the plastic lid on the IKEA thermos shattered. Plus, the heat retention of the Zojirushi is covered by a five-year limited warranty.

The Zojirushi has a four-piece lid that comes apart, which allows you to deep-clean all its crevices. We liked it better than the single-piece lids on most of the other thermoses we tested, which have hard-to-reach threads that look like they would trap gunk. After long-term testing this thermos, I ended up losing a small rubber stopper that plugs into the top part of the lid. This hasn't affected heat retention, but sometimes foods will leak into the thermos's cap, so I prioritize unscrewing all of the parts of the lid to make sure I can get it really clean. Despite this minor leak due to the missing piece, the Zojirushi has never leaked outside of the container itself. I’ve also seen it survive trips through the dishwasher without a ding, even though Zojirushi recommends hand washing the thermos. We also like that the Zojirushi comes in a range of sizes, including 11.8-, 16.9-, and 25-ounce jars, and an array of colors, including pink, aqua blue, dark brown, cream, and stainless steel.

Flaws but not dealbreakers: We found that after just 2 hours, cold milk in the Zojirushi rose to 46 °F (after 6 hours, it was 52 °F). Tuna rose to 49 °F after 2 hours; after 6 hours, it was 63 °F. None of the thermoses we tested, however, did any better, even after prechilling them with ice water (Zojirushi recommends filling the thermos with cold water for one to two minutes before filling with food). Packing the thermos in a bag or lunch box with ice packs can help foods stay cold, but ultimately we found that these thermoses are best for retaining heat (apologies to our reader who requested a thermos to keep ice cream frozen while hiking).

Although we like that the Zojirushi's multi-part lid is easy to clean, it's a bit more difficult to put back together afterwards. The rubber gasket is tricky to get on, and keeping track of the small four parts takes effort. Also, unlike some larger thermoses, the Zojirushi's lid also doesn't double as a cup, so you will likely eat straight from the jar.

Plain pasta also cooled more quickly in the Zojirushi, dropping from 178 °F to 82 °F over 6 hours, but the results were similar in all the thermoses we tested. Solids like pasta cool more quickly than liquids, so any thermos is most effective when used with soup, stew, oatmeal, or other liquidy foods. To keep foods hotter for longer, we recommend preheating the thermos.

We tested a jar with the stainless finish, but have read several Amazon reviews noting that the coating on the blue, pink, and tan versions of the food jar can scratch. We’ve also found that the finish on Zojirushi's travel mugs develops small nicks and scuffs over time, but this wear and tear doesn't affect performance. We will continue to long-term test the jar to see how it holds up.

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The 10-ounce Funtainer is durable and easy for small hands to open. Plus it comes in lots of colors and prints.

*At the time of publishing, the price was $13.

Why we love it: In our tests, the 10-ounce Thermos Funtainer kept food hot, didn't leak, didn't break when dropped, and was easy to clean. We prefer it for kids over the 12-ounce Zojirushi because it comes in an array of fun prints and colors, and we think the slightly smaller size will be easier for kids to use. The Thermos also costs less in case it gets lost and needs replacing. The Funtainer fits neatly into smaller lunch boxes like our top pick and can hold a 10-ounce serving of noodles, veggie chili, or hot cereal. Although the Funtainer kept foods hot, it didn't do as well as the Zojirushi: after 4 hours, soup in the Funtainer had cooled from 193 ºF to 147 °F, and at 6 hours, it measured 130 °F. In comparison, the Zojirushi kept soup at a hotter 144 °F after 6 hours.

None of the thermoses, including the Funtainer, leaked in our tests. The Funtainer also held up better than the competition in drop tests. Its plastic lid didn't break, whereas the lid on the kid-friendly Contigo Food Jar fractured to reveal styrofoam below an outer plastic layer. The Funtainer's lid doesn't get slippery when wet and is also easier to twist on and off than the raised triangle-shaped lid on the Contigo. With its uniform, cylindrical shape, the Funtainer fits easily into all of our lunch box picks. It also comes in a variety of prints and colors that will appeal to kids of different ages (and adults can select a solid color option). Thermos offers a 30-day warranty period for defective products.

Flaws but not dealbreakers: None of the thermoses we tested were able to keep cold foods at food-safe temperatures during our tests, including the Funtainer. After 2 hours, tuna salad that started at 40 °F rose to 49 °F; at 6 hours, it measured 63 °F. If you’re nervous about it, packing the thermos in a bag or lunch box with ice packs can help foods stay colder for longer.

The Funtainer has a removable rubber ring to seal the thermos, but since it doesn't totally come apart, the lid has more receded nooks than the Zojirushi Food Jar, so it's a little harder to clean.

This container keeps food hot for hours and comes apart easily for cleaning.

*At the time of publishing, the price was $30.

The 10-ounce Funtainer is durable and easy for small hands to open. Plus it comes in lots of colors and prints.

*At the time of publishing, the price was $13.

For this guide, we read six roundups and articles on thermoses from publications like Good Housekeeping and Popular Mechanics and blogs like A Well Paced Life and Mighty Nest. We also checked out best-selling models from kitchen and home stores like Amazon, IKEA, Target, Walmart, the Container Store, and Storables. Then, we took a closer look at offerings from notable brands like Thermos and Zojirushi. We considered models designed for kids as well as a general audience. We preferred thermoses that come in multiple sizes and colors, and we tested smaller size options (ranging from 10 to 13.5 ounces, with a few 16- and 17-ounce sizes) when possible because we wanted a thermos that was easily portable and fit into our picks for the best lunch box or a bag.

A great thermos should keep foods at a food-safe temperature—below 40 °F for cold foods and above 140 °F for hot foods—for long periods of time. Thermoses are meant to hold liquidy foods like soups or stews, and they shouldn't leak. Because accidents happen, they also shouldn't break or dent significantly when dropped. Most companies recommend hand-washing thermoses to preserve their vacuum insulation, but the lids and jars should be intuitive to take apart and clean.

In our tests, we considered how long thermoses kept soup and plain bow-tie pasta warm, how long they kept milk and tuna salad cold, whether thermoses leaked, durability, and how easy they were to clean. We heated tomato soup to a boil and added it to the thermoses, checking the temperature over six hours in two-hour increments, and we did the same with pasta. Our pasta tests, however, weren't conclusive—it took us longer to fill thermoses with wider bow-tie noodles after straining them than it did to ladle in boiling-hot soup, and we think pasta may have cooled during the process.

We also tested each thermos with cold foods, filling them first with milk and then with 4 ounces of tuna salad, both at 40 °F. Then, because both milk and tuna rose above food-safe temperatures in all of the thermoses after just 2 hours, we repeated the tuna test after prechilling the thermoses with 40 °F ice water (a few brands, like Thermos and Zojirushi, recommend prechilling thermoses, but we originally skipped this step because in real life, we would never take the time to do this). Even after prechilling the thermoses, none kept tuna within the USDA's safe temperature guidelines after 2 hours.

After filling thermoses with soup, we shook them in a backpack and held them upside down to check for leaks. We dropped thermoses from 4 feet onto pavement to see if they were damaged after a fall. To see how easy models were to clean, we took them apart and hand-washed them. We also made sure that the thermoses we tested fit in our picks for the best lunch boxes.

To keep foods hotter for longer, both Thermos and Zojirushi recommend preheating your thermos by filling it with hot water for five to 10 minutes before dumping it out and adding foods. You can do the same thing with ice water to pre-chill your thermos before adding cold foods.

Like most of the thermoses we looked at, the Zojirushi is not dishwasher-safe and needs to be hand-washed. Putting it in the dishwasher can degrade its ability to retain heat. The Funtainer is top-rack dishwasher safe, but Thermos still recommends hand-washing it because "harsher detergents and hot water may affect the appearance." To clean the hard-to-reach places in the Funtainer's lid, we recommend soaking it in warm, soapy water.

Even though the lifetime warranty of the Hydro Flask Food Flask impressed us, the thermos is only meant to keep foods hot for three hours, and it dented significantly when dropped.

The Thermos Stainless King 16 Ounce Food Jar with Folding Spoon kept soup hotter than most of the competition in our tests. But it has a wider girth and a bulkier, ridged shape compared to our pick, making it harder to hold and fit in a lunchbox.

The smooth curves and brushed steel of the Black and Blum Food Flask are sleek, and the faux leather strap and spoon attachment charmed us. But the flask isn't as widely available as our pick, and the strap-and-spoon contraption isn't functional—the spoon would be exposed to germs in a bag, and the strap stains easily.

The 18-ounce Stanley Classic Thermos Vacuum Food Jar can hold a lot of food and has a separate cap to eat from. But it doesn't offer a range of sizes like our pick and won't fit in a lunch box or tote bag.

We like the affordable MIRA Lunch Food Jar, but it didn't keep soup as hot as most of the other thermoses we tested. It also seems that the company is having trouble keeping the MIRA jars in stock in multiple colors, so we’re concerned about future availability.

Anna Perling

Anna Perling is a former staff writer covering kitchen gear at Wirecutter. During her time at Wirecutter, she reported on various topics including sports bras, board games, and light bulbs. Previously she wrote food and lifestyle pieces for Saveur and Kinfolk magazines. Anna is a mentor at Girls Write Now and a member of the Online News Association.

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