Stainless Steel Lunch Box vs Plastic: Which is better?

By Anna K.

Last Updated July 11, 2025

Choosing the right lunch box can feel surprisingly complicated. While stainless steel and plastic lunch boxes each offer certain benefits, they also come with their own set of potential drawbacks.

After weeks of packing meals, reheating lunches, and seeing how they held up, here's what I found:

Is a plastic or stainless steel lunch box safer?
- Stainless Steel: Typically, stainless steel lunch boxes are BPA-free and unlikely to release harmful chemicals into your food, even when heated. Just look inside the restaurant kitchens and you'll see nothing but stainless steel.
- Plastic: While plastic lunch boxes can also be safe, there’s a broad public debate that plastic may contain BPA and other toxins, especially when used with hot foods. Choosing BPA-free plastic options can reduce these risks, though uncertainty might still linger about long-term effects.
- Tested: When using stainless steel lunch box, I never noticed any weird taste or smell, even after reheating, which gave me peace of mind. While I carefully picked BPA-free plastic lunch box, i won't lie, there were times I still wondered about safety when reheating food. There were no immediate issues, but the nagging worry stayed.
Insulation: Which Kept My Lunch Warm?
- Stainless Steel: While insulated stainless steel lunch boxes can keep food warm for hours, there are now electric lunch boxes available that heat up your food, so you don't need to worry about insulation at all.
- Plastic: Generally, plastic lunch boxes are less effective at temperature retention and usually require additional insulation accessories like ice packs or insulated bags to maintain temperature.
- Tested: I tried the HeatsBox cordless electric lunch box and it heated my food in under 30 minutes. So I didn't have to worry about keeping my lunch warm or dealing with lukewarm leftovers. When I tested a plastic lunch box, after six hours my food was, well, cold. With plastic boxes, you pretty much need a microwave nearby if you want to reheat your food properly.
Is stainless steel lunch box microwave safe?
- Stainless Steel: Usually, stainless steel lunch boxes aren’t microwave-safe, as metal reacts poorly to microwaves and could cause sparks. For reheating meals, you’ll typically need an alternative solution.
- Plastic: Plastic containers can often be microwaved, but only if specifically labeled microwave-safe. But after frequent use, some boxes may show signs of warping, which made me question their longevity.
- Tested: No, I did not test putting stainless steel into my microwave. Instead I used HeatsBox electric lunch box that comes with a stainless steel container. It warmed up my meal in 30 mins.
Durable and Eco-Friendly: Considering Long-Term Use
- Stainless Steel: Often seen as more environmentally friendly due to recyclability and durability, using stainless steel lunch boxes significantly reduces waste. They are built for longevity, although not completely indestructible and can get dented if dropped frequently.
- Plastic: Plastic lunch boxes are typically lighter and convenient, but they can become brittle, crack, or warp over time, especially if frequently exposed to heat or cold. They also contribute to long-term pollution as they take hundreds of years to decompose.
- Tested: Final take, I felt better about using stainless steel, knowing it's built-to-last. Even after extensive use, it still looked almost new, indicating it would last a long time.