Dishwasher is fine for the box, but hand-wash the seals.

You can put the whole lunch box in the dishwasher, but the silicone seals will wear out faster than if you just hand-washed them. The box itself and the lid are usually fine — it’s the rubbery gaskets that take the beating.

Dishwasher heat and aggressive detergents break down silicone over time. The seals start to dry out, lose their flexibility, and eventually crack or warp. Once that happens, the lid won’t snap on as tight, and you’ll get leaks. The same goes for any plastic clips or hinges — they can get brittle and snap after repeated cycles.

My rule: box and lid go on the top rack, seals go in the sink. Takes five seconds to wash them with soapy water, and your lunch box will last years instead of months. If you’re lazy (I am), at least put the lid on the top rack and skip the heated dry cycle — it’s the heat that does most of the damage.

Check the manufacturer’s label if you’re unsure, but “top-rack safe” usually means “survives, but not forever.” Silicone is cheap to replace, but you can’t always buy it separately, so keeping it out of the dishwasher is the smart move.