The Stojo collapsible container is the one you want.

The Stojo Collapsible Food Container is the best space-saving lunch box for a desk drawer or a bike bag because it actually folds flat when you’re done eating.

It’s food-grade silicone, so it squishes down from about four inches to an inch and a half. That means it slides into a shallow drawer or tucks into a side pocket without eating your space. The lid snaps on tight enough to carry soup, and it’s microwave-safe (lid off). Sizes range from 12oz to 36oz, so you can match it to your appetite.

If you’re only carrying a sandwich or a wrap, a beeswax cloth is even smaller and basically flat. But for actual leftovers, the Stojo is the one. Nothing else in the collapsible category does it as cleanly without a bunch of fiddly parts.

And future you will be glad you didn’t buy a rigid box that only fits when empty.