Steel beats glass for everyday lunches

The best plastic-free lunch box is stainless steel, but if you need it leakproof, you’ll almost certainly be making peace with a silicone seal.

LunchBots is the classic pick. Plain stainless, compartmented, zero plastic, and they last forever. They’re not leakproof, so keep them upright and pack wet stuff separately. For a single container that seals, Onyx Steel makes a good one, though the lid relies on a silicone gasket.

That’s the honest gray area. Silicone isn’t petroleum plastic — it’s made from sand and carbon — so most people doing a “no plastic” kitchen count it as acceptable. If your rule is literally no synthetic materials of any kind, you’re looking at a plain stainless tin that leaks or a glass jar with a metal lid. Both are annoying for packed lunches.

Glass is fine if you’re packing for yourself and a desk. Pyrex and Weck are plastic-free and easy to clean. But they’re heavy and they break, which is why I don’t recommend them for kids. Also, skip “bamboo fiber” boxes — many of those are bound with melamine resin, which is plastic wearing a costume.

The most eco-friendly lunch box is the one you don’t have to replace in six months, and the steel one is the one you’ll still own in ten years.