Are Lunch Boxes Microwavable – Some are, some aren’t

When looking for your next lunch box it can be difficult to know which one will suit you best Given most workplaces now have a small kitchen which includes a microwave one of the most common questions when choosing a lunch box is whether you’ll be able to heat your lunch in a microwave.

As a general rule lunch boxes made from plastic, glass silicone and in some cases bamboo are microwaveable however you should always check the manufacturer’s instructions before use in the microwave. Stainless steel lunch boxes and fabric lunch bags are not suitable for use in the microwave.

By the way, if you’d like more comprehensive information about each type of lunch box I’d recommend reading my article “What is the Best Material for Lunch Boxes – Revealed” after this.

Before we look at the common types of lunch boxes let’s understand why some lunch boxes are not suitable for use in the microwave.

Why Should Some Lunch Boxes not be Placed in a Microwave?

From a lunch box perspective, one of the main things to avoid is a lunch box or lunch bag that contains any kind of metal. This might be obvious in some cases such as lunch boxes made entirely from metal but may not be that obvious with other types of lunch containers.

These days lunch boxes come with all kinds of attachments, features and design elements that might not be appropriate for use in the microwave and it should be noted that some of these are hidden away.

Other less obvious reasons are that some lunch boxes are made from material that when used in the microwave may leach chemicals into the food you’re trying to heat, or perhaps weaken the container itself as it’s not designed to be used with piping hot food.

Some lunch containers are just not practical for heating food in the microwave whether or not they can actually be used for doing so.

A note of caution: it’s super important to read the manufacturer’s labelling before use.

Below is an image of the Black and Blum stainless steel lunch box which clearly shows the “Do not use in the microwave” symbol on the left hand side.

Now we know why some lunch boxes can’t be used in the microwave lets take a look at the individual types.

Which Lunch Boxes Can Be Used in the Microwave

Many lunch box manufacturers now subscribe to placing the common microwave safe symbols either etched on to the product itself or on the out packaging. Below are examples of these symbols:

1. Plastic

In most cases these days plastic lunch boxes are microwaveable. In the unlikely event that you do choose this non eco-friendly material for your next lunch box, you should go for a plastic container that is BPA free.

Clear instructions should be outlined on the manufacturer’s labelling and good quality boxes will show the microwave safe symbols.

2. Glass

Glass lunch boxes work really well in microwaves but you should still check that the container you’ve bought, or are going to buy, can be used in a microwave.

There are some products on the market made from low-grade glass which is not microwave safe so you’ll want to avoid those.

Also worth noting is that many glass lunch boxes are leakproof and as such have lids that are not usually made from the same glass material. Check the manufacturer’s instructions but if in doubt you should remove the lids or any other accessories such as utensils before heating in the microwave.

3. Silicone

Silicone is a type of plastic, slightly more eco-friendly and in the main can be used in the microwave especially if the lunch box is made from 100% silicone.

As with some of the other lunch box types, there are some products where silicone is just a small part of the box so well worth checking for those obvious signs such as metal which would prevent it from being used in the microwave.

4. Bamboo

Lunch boxes made from bamboo are still in their infancy. Many “bamboo” lunch boxes actually consist of a plastic or metal container and a bamboo lid. Clearly, these should not be used in the microwave.

But there are a few companies now making bamboo lunch boxes where the container section of the box is made from bamboo fibre and some of these products now have microwavable options in their range.

Bambox is one such supplier of bamboo lunch boxes.

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Which Lunch Boxes Can’t Be Used in the Microwave

1. Stainless Steel

As I’ve already mentioned metal containers are a big “no” when it comes to microwaving your lunch.

There’s not much more to say about stainless steel lunch boxes – just avoid microwaves at all costs!

2. Fabric

Fabric lunch bags often have metal accessories such as zips, clasps and handles and so are not suitable for the microwave.

In addition, many lunch bags have insulated linings which again make them impossible for use in the microwave and to be honest, I feel that if you are looking to heat up your lunch you’re probably not going to do so in a fabric bag.

One thing to note though is that combining an insulated fabric bag with another type of lunch box might mean you won’t need the microwave at all as the insulated lining will keep your lunch hot from home.

Which Eco-Friendly Lunch Boxes Can Be Used in the Microwave

From the lunch boxes that can be used in the microwave, there are a couple of choices that are more eco-friendly that the others.

Glass is recyclable and reusable and lasts a very long time so this type of lunch box makes it onto the zero waste lunch box list.

In addition to glass, a bamboo lunch box is also a great option when it comes to choosing a product with eco credentials.

Key Takeaways

So in summary there are four common materials that are used to make lunch boxes that can be used in the microwave. Here’s a handy lookup table:

Lunch Box Material	Microwave Safe
Stainless Steel	No
Bamboo	Check
Plastic	Yes
Glass	Yes
Silicone	Yes
Fabric	No

I hope this information has been useful and please do leave a comment below, I’d love to hear your thoughts.

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