Stanley Thermos Review

This summer, I spent five months living and working at Camp Denali, a wilderness lodge in Denali National Park, Alaska. Backcountry hiking is the main attraction, and on each outing, our naturalist guides carry more than 10 pounds of gear, including a slew of emergency preparedness supplies. But the item that I find most important isn’t truly an “essential.” It’s a thermos full of hot chocolate. 

Our guides carry Stanley thermoses on every outing into the park so guests can enjoy a hot beverage after a long day of hiking. Ranked as one of the best thermoses in our review, the Stanley Classic Legendary bottle keeps beverages steaming hot for many hours—but most impressively, the thermos is basically indestructible. In fact, Camp Denali has used the same thermoses (cleaned after every use, of course) for over 30 years. 

What’s a Thermos Good For?

If you like to bring hot drinks on the go, a thermos is an excellent option. It keeps the contents hot (and out of the “temperature danger zone” where bacteria can grow) for up to 24 hours, eliminating the need for refrigeration or reheating.

What’s the difference between a travel mug and a thermos, and how do you know which one best suits your needs? “Compared to travel mugs, thermoses are bigger (usually at least one liter compared to 16 ounces), have thicker vacuum insulation, and have screw-on, leak-proof caps without a sipping port,” explains former Serious Eats writer Jesse Raub in his review of thermoses. “They’re better at retaining heat for longer periods than travel mugs, and most are secure enough to toss into any bag without fear of coffee (or iced tea) leaking.” 

Pack a thermos full of hot chocolate for a family trip to the ice rink, or tote a carafe of coffee to the office. No fear of spillage, and no need for reheating. (PS: If you want a thermos to keep your lunch warm, check out the best food thermoses.)

What Makes the Stanley Thermos Great?

There are two primary ways to judge a thermos’ effectiveness. First, its insulating properties: Does it keep the contents at the desired temperature (warm or cold), and for how long? Most of the thermoses in our review—including the Stanley Classic Legendary bottle—passed this trial easily, maintaining a temperature of at least 170°F (hot enough to burn most people’s tongues) for eight hours. 

The Stanley bottle performed exceptionally well in the hot and cold retention trials, but so did plenty of other thermoses, including ones from Zojirushi and MiiR. The most distinctive factor, then, in determining the quality of a thermos is its durability. This is the area where Stanley distinguishes itself: It has survived more than 30 years of heavy use in the Alaskan backcountry.

Manufactured in 1987, Camp Denali’s Stanley thermoses have weathered all kinds of heavy use—jostling around a backpacking pack, rolling around the back of a bus, tumbling down a gravel hill, etc. They’ve certainly endured exterior wear and tear—most of the original green paint has chipped off, revealing the stainless steel body—but they still work just as well as new. 

That’s because Stanley thermoses are built to last. They’re constructed from 18/8 stainless steel, with double-wall vacuum insulation that keeps heat in and prevents spills. As long as the vacuum still seals properly, an older thermos will continue to perform. The vintage thermoses reliably keep water steaming hot for more than six hours, so after a long day’s trek, I’m always rewarded with a hot cup of tea or cocoa.

In addition to its impressive durability, there are a few design details I appreciate about the Classic Legendary thermos. The thermos itself is tall and thin—easy to slip into the water bottle sleeve on a backpack—and it comes with a collapsible handle, making it comfortable to carry. (If you prefer one without a handle, that’s an option, too.) The bottle’s lid doubles as a drinking cup, so it’s easy to pour yourself a hot beverage on the go. Beneath the lid, a twist-and-pour stopper minimizes the risk of spillage and further limits the liquid’s exposure to the elements, keeping it hotter for longer. Plus, they last a lifetime—just ask the guides in Alaska.

FAQs

How much liquid does the Stanley thermos hold?

The Stanley thermos comes in four sizes: 1.1 quarts, 1.5 quarts, two quarts, and 2.5 quarts. We use the 2.5-quart model, which holds 10 cups of liquid, to serve hot beverages to 10 to 12 people.

How long will the Stanley thermos stay hot?

According to Stanley, the thermos will stay hot for 24 hours. In Serious Eats’ tests, the Stanley thermos maintained a temperature of at least 170°F for eight hours and 135°F for 24 hours.

How do I know if my thermos’s vacuum seal is broken?

If your thermos is leaking, that’s a sure sign that the vacuum seal is no longer effective. If you open your thermos after a couple of hours and the contents are no longer hot, that’s another indicator that the vacuum seal has been compromised. If you’re using the thermos exclusively for hot beverages like coffee, the primary risk of a faulty vacuum seal is leakage—annoying, but not necessarily dangerous. If you’re using the thermos for food storage, however, a compromised vacuum seal can result in potentially hazardous bacteria growth.

Why We’re the Experts

• Zoe Denenberg is a chef, baker, and food writer. 
• She has spent the past five-plus years working in kitchens across the country, including an artisanal ice cream shop in Birmingham, Alabama, and a Michelin-starred restaurant in New York City. 
• She is currently the executive chef at Camp Denali, a wilderness lodge in Denali National Park, Alaska, where the Stanley thermos has been a reliable hiking companion for decades.