Hot leftovers in plastic are okay — check the number first.

Putting hot food in a plastic lunch box is generally fine as long as it’s BPA-free and not boiling — but you should check the recycling code before you scoop.

The BPA worry is real but simple: heat makes plastic leach more, and BPA is the one you don’t want in your food. If the container says “BPA-free” on the bottom or the label, you’re good. The recycling code does the same job: #1, #2, #4, and #5 are safe. Avoid #3, #6, and #7 unless #7 specifically says BPA-free, because that catch-all code often hides the bad stuff.

One practical note: “hot” should mean “steaming, not straight-off-the-stove boiling.” A hot meal is fine. A container full of just-boiled soup is not, especially if the plastic feels thin. Wait a minute or two, or go with glass if you make soups and stews regularly.

When in doubt, glass is never a bad answer.