Both keep your drink hot or cold. Both come in stainless steel. So what's the actual difference between a thermos and a tumbler, and which one should you grab on your way out the door?
The short answer
A thermos is a sealed, bottle-style vacuum flask built to hold temperature as long as possible and survive a ride in your bag. A tumbler is an insulated cup with a lid, built for easy sipping at your desk or in your cupholder. Thermos for all day on the move, tumbler for everyday drinking.
Thermos started out as a brand name, and it's now everyday shorthand for any vacuum-insulated flask. A thermos has double stainless steel walls with a vacuum between them, a narrow mouth and a screw-on lid, often with a pour spout or a cup that doubles as the cap.
That sealed design is what makes a thermos the champion of long hauls. It keeps coffee, tea and soup hot (or drinks cold) for many hours, and it can ride sideways in a backpack without leaking.
A tumbler is a cup-shaped drink container with a lid. Today's insulated tumblers use the same double-wall vacuum construction as a thermos, so they keep hot drinks hot and cold drinks cold too. They're just built for convenience: a wide mouth for ice, a press-on or slide lid, often a straw, and a shape that fits most cupholders.
Curious how the insulation actually works? Here's the science behind insulated tumblers.
| Thermos | Tumbler | |
|---|---|---|
| Shape | Tall bottle or flask with a narrow mouth | Cup shape with a wide mouth |
| Lid | Screw-on, often with a pour spout or cup | Press-on or slide lid, often with a straw |
| Leaks | Usually leak-proof when sealed | Usually spill-resistant, not leak-proof |
| Temperature | Longest hold, thanks to the sealed lid | Hours, though a sip opening lets some heat out |
| Drinking | Pour or unscrew first | Sip anytime, one-handed |
| Best for | Soup, all-day coffee, hikes, job sites | Commutes, desks, the gym, everyday hydration |
Thermos for the long haul. Tumbler for the daily grind.
Choose a thermos if your drink needs to stay hot until dinner, you're packing soup for lunch or it's going in a bag, a toolbox or a tent.
Choose a tumbler if you want something to sip from all day, you drive a lot and need it to fit a cupholder, or you like plenty of ice and a straw.
Lots of people end up owning both, and that's not a bad plan. Wondering whether a tumbler will survive your bag? Read are drink tumblers leak-proof?
Is a tumbler the same as a thermos?
No. Both can be vacuum insulated, but a thermos is a sealed flask and a tumbler is a lidded cup made for sipping.
Which keeps coffee hot longer?
Usually a thermos, because its sealed screw-on lid lets out less heat than a tumbler's sip opening.
Can you put hot drinks in a tumbler?
Yes, if it's an insulated stainless tumbler. Just be careful sipping right after you pour.
Is a thermos leak-proof?
Most are when the lid is fully screwed on, which is why they're a better pick for bags.
Branded drinkware that gets used
Tell us the colors, the quantity and your logo. Our 20 oz and 30 oz tumblers include a 3″ laser engraving.