Your electric lunch box can go in carry-on

You can bring an electric lunch box in your carry-on — the TSA allows it, and the battery rules are almost never a problem.

The heating element isn’t the issue. TSA treats it like any other small appliance, so if your lunch box just plugs into a wall, there’s zero worry. If it’s rechargeable with a lithium battery, it falls under the portable electronics rule: under 100 watt-hours is fine for carry-on, and basically every electric lunch box on the market is well below that. You’ll likely have to pull it out of your bag for the X-ray bin, same as a laptop.

The real gotcha is the food inside. If you’re carrying soup, yogurt, or anything liquidy, it’s subject to the 3-1-1 rule — max 3.4 ounces (100 ml) if it’s in your carry-on. Solid food is fine. Also, a box full of food can look weird on X-ray and earn you a bag search, so it’s smarter to pack it empty or with solid snacks and plug it in once you’re through.

Just don’t fly with a full bowl of soup and you’re good.