For hot soup, skip the lunch box and get a food jar.

The best “insulated lunch box” for soup is a Thermos-style food jar—not a lunch box. Something like the Thermos Stainless King 16 oz or 24 oz food jar will keep soup blazing hot until lunch, and it won’t leak all over your bag.

Regular insulated lunch boxes are designed to keep things cool, not hot. Even the good ones won’t hold soups at a safe, steaming temperature from 8 a.m. to noon. A vacuum-insulated food jar is what actually works. The Thermos Stainless King is the classic pick: cheap, durable, and it holds heat like a Champ. Zojirushi makes a slightly more expensive one that’s even better at sealing in heat, but the Thermos is all most people need.

The trick to making it work: fill the jar with boiling water, put the lid on, and let it sit for a minute or two while you heat your soup on the stove. Dump the water, put the hot soup in, and seal it immediately. This pre-heats the walls of the jar so the soup doesn’t cool down the moment you pour it in. Do that, and you’ll still be burning your tongue at noon.

If you’re carrying stew, chili, or noodle soups with chunks, get the wide-mouth 24 oz version. It’s easier to eat straight out of and cleans up better.

Future lunch-you wants hot soup, not lukewarm regret. Get the food jar.