For soup, get a screw-top jar. Clip lids lie.

For soup or yogurt, the only lunch box you can trust is a screw-top jar. Clip-lid plastic containers will leak eventually, no matter what the package claims.

The physics is simple. A clip-on lid is held shut by tension, and that tension loosens over time as the plastic flexes in a bag. A screw-top lid presses a gasket directly into the rim with threads — it’s a seal, not a latch. That’s why thermoses and mason jars don’t leak and bento boxes do.

What to buy: a vacuum-insulated steel food jar with a screw lid. It keeps soup hot until noon, holds yogurt fine, and the threading is forgiving. If you want glass, a wide-mouth mason jar with a plastic storage cap works, but it’s heavy and won’t keep anything cold. If you absolutely need a compartment container, look for one with a thick silicone gasket and locking clips on all four sides — not just two. Then test it: fill with water, screw/clip it shut, turn it upside down over the sink. That’s your leak test.

And don’t trust “leak-proof” printed on the box. Trust the lid design. A soggy laptop is not where you save six bucks.