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Ziploc Bags: Are They Microwave Safe?

When it comes to using a microwave, there are many gray areas. What things are okay to microwave, and what things aren’t? One question you may be wondering is whether it’s actually a good idea to put a ziploc bag in the microwave.

Is it a good idea to heat them?

There’s probably been at least one point in your life where you’ve seen someone trying to microwave their food using a Ziploc bag. You may have thought it was fine, or perhaps you thought it was dangerous!

Ziploc Bags Are They Microwave Safe

The truth of the matter is that people don’t really have a solid answer about whether it’s okay to use plastics with food. There are a lot of arguments about it, and there are people on either side.

For instance, there are some big brands out there that have built an empire on claiming microwave plastics are safe and that it’s totally fine to store food in them. With that being said though, what’s the truth?

The Construction of Ziploc Bags

So the first question is what are these things actually made out of? Ziploc is much like any other kind of sandwich bag. It’s specifically made out of ‘film’.

What’s that? It’s basically a really thin kind of plastic that tends to consist out of high density polyethylene – or HDPE, or it’s made out of another kind of polyethylene, low density polyethylene or LDPE for short.

In most cases, any kind of plastic packaging resin will be given a number. This number will tell you about the number of polymers in the plastic. If you look on the bottom of the plastic container then you will be able to find this number.

Most ziploc bags are made out of plastic that is dioxin free, BPA free and they can usually be recycled without too much trouble. With that being said though, they don’t actually consist of recycled materials.

Okay, so at what temperature do these things melt? Since they are made out of polyethylene that softens at around 195 Fahrenheit or 90.5 Celsius, these bags will likely melt if you pour boiling water inside of the bag.

Alternatively, if you submerge them into boiling water they will likely melt that way.

Should I Microwave Food Using a Ziploc Bag?

There’s a good chance that you’ve seen people microwaving all sorts of things in ziploc bags without any consequences. With that being said, it’s really not the best idea to try it yourself.

Sure, it will most likely work just fine, but it’s a lot better to check out the directions from the manufacturer before you go ahead and put your ziploc bags in the microwave.

These products can be used without a hitch so long as the instructions on the label are followed properly.

These products are suitable for ‘defrosting and reheating food in microwave ovens, as well as room, refrigerator and freezer temperatures’ according to the Ziploc website.

So is it safe to defrost your ziploc bag in the microwave? Well, it can be safe so long as you are only reheating and defrosting the contents of the bag. It’s not suitable for anything else.

So in essence, you should not be cooking using a ziploc bag. The manufacturer has highlighted that this is not a good idea, so it’s best to take heed of the warning.

If you are cooking things using heat, you’re likely going to be working with temperatures that are far past the polyethylene plastic’s melting point. That’s why it’s usually a better idea to only do things like reheating and defrosting in the microwave.

What about vegetables? This is another resounding no. Stay away from cooking your vegetables in a ziploc bag. While it is a very common thing that people do, it’s a terrible idea.

Steaming creates even more heat as the evaporated water from the vegetables circulates around the bag, meaning there’s an even higher chance that the bag will melt. It’s essentially like sticking it in boiling water – it’s a bad idea.

One thing that you may not know is that you will cause a lot more danger to yourself if you steam things rather than if you boil them. The burns from steaming are usually significantly worse than burns from boiling.

There’s even 9 times more energy produced from steaming than there is from boiling water.

If you are aware of all of this, then you will know that the temperature will be a lot higher when you are steaming things. The temperature is simply going to be too high for your little plastic ziploc bag to actually deal with.

What about sandwich bags, then? Well, these most certainly aren’t safe. The exception to this rule is if the maker of the bags has actually said that it’s okay to use the bags in question in a microwave.

Freezer bags? It’s worth noting that a ziploc freezer bag is generally made to handle defrosting and reheating food.

With that being said though, you will need to be very careful, because much like a standard ziploc bag a freezer bag still isn’t supposed to be dealing with high levels of heat.

So how long should you be putting a ziploc bag in the microwave? Well, the manufacturer hasn’t actually given any guidelines on this on their website.

Most manufacturers, including ziploc,  will just tell you that you shouldn’t overheat any of the contents inside of the bag because the bag could end up melting.

If you are going to use the microwave, then make sure that you only put it on medium to low power, and microwave it for 30 seconds at a time.

You don’t want an excessive amount of steam building up in the bag either, so keep a little bit of the bag open to make sure that that doesn’t happen.

What You Need To Know Before Putting Ziploc Bags In The Microwave

What You Need To Know Before Putting Ziploc Bags In The Microwave

The great thing about ziploc is that the bags are made to be safe for use in a microwave. With that being said, you need to be really careful and read the manufacturer’s instructions before you do so.

As we have previously discussed, ziploc has said that you should try not to overheat anything inside of the bag.

You need to be especially careful if you are microwaving things with a lot of sugar or fat because they can get a lot hotter than anything pure water can.

These hot temperatures may end up resulting in your ziploc bag melting if you aren’t careful.

As we also said earlier, it has been said by the manufacturer that you should only put ziploc bags in the microwave if you are planning on defrosting or reheating them.

It’s a bad idea to cook them because they’re simply not designed to deal with heat of that magnitude.

If you are going to put these bags in the microwave for whatever reason, put them onto a microwave safe dish and you should try to microwave it in just 30 second intervals each time.

Put it on low heat and don’t fully seal up the bag as you don’t want the steam to build up too much inside of it. 

When you take it out of the microwave, make sure that you are checking the bag each time to ensure that you aren’t heating the plastic up too much.

If you are meal prepping, it’s a good idea to cut the food into smaller sections if you are going to be putting it in ziploc bags. This is a good idea because it means that it won’t take as long to reheat the contents when you put them in the microwave.

Not only that but there’s also a much lower chance that the bag will overheat since it won’t need to be in the microwave for as long.

Frequently Asked Questions

Are Ziploc bags freezer safe?

Yes! Ziploc bags are designed to withstand freezer temperatures, so they are suitable for storage in the freezer.

Are Ziploc Bags BPA free?

They are indeed BPA free. They aren’t toxic to use either – just make sure you don’t overheat them.

Can you put boiling water in Ziploc bags?

No – they aren’t designed to be able to handle temperatures that are that hot. Boiling water is far too hot to go in a ziploc bag.


It can be quite useful to put your ziploc bags right into the microwave. If it’s worked for you before then it can be tempting to continue to do what you were doing before.

With that being said, it doesn’t necessarily mean that it’s the healthiest thing for you to be doing. The manufacturer has even said things to suggest that microwaving ziploc bags may not be the best idea.

If you have taken the time to look into this topic a little more, you will probably now be aware that it’s a lot safer to just put your food into a ceramic or a glass container since it’s unlikely to come with the same health risks.

Just make sure that the containers are microwave safe first.

If the food is covered up then it’s more likely to heat up better since the steam is well distributed. In short, stay with the microwave safe containers instead of ziploc.

Jess Smith