Get a Thermos for hot. Ello for the microwave.

For soup you want to eat immediately, a wide-mouth Thermos food jar is the most leak-proof thing you can buy. I’ve thrown a Thermos King in a backpack sideways many times — zero leaks. The screw-on lid plus silicone gasket is the only design I fully trust with thin liquid.

Important distinction: “leak-proof” on a snap-lid plastic container means almost nothing. Soups are thin, and that kind of lid only seals when there’s a real silicone gasket and a latching mechanism. So you’ve got two use cases:

You need it hot at lunch: Get a Thermos King (or Stanley food jar). It screws shut, keeps soup hot for 7+ hours, and won’t leak. Don’t overthink it — this is a solved problem.

You need to microwave it at work: You want Ello Duraglass or Glasslock. Both use glass with a 4-side locking lid and a silicone seal. That’s the gold standard for a liquid-proof container you can reheat directly. Oxo Good Grips is a decent alternative if you prefer plastic.

The rule: screw-on lid or 4-clip lock with a real rubber gasket. If it just snaps shut over the rim with no gasket, it will eventually betray you.

Soups are liquid — the seal is the only thing between you and a briefcase disaster.