Microwave Oven

Are Plastic Cups Microwave Safe? – Learn Here

Are plastic cups microwave safe? Should they be used in a microwave at all?

While some plastic cups are safe to be used in the microwave, others aren’t. Really thin plastic cups should not be used in the microwave at all. They could melt. Also some of the materials used in making these plastic cups are not safe for microwave use.

In this article, we will discuss more about plastic cups, if they can be used in the microwave, what plastic cup type can be used.

Are Plastic Cups Microwave Safe

Are Plastic Cups Microwave Safe

Most plastic cups are NOT microwave safe

Not all plastic cups are microwave safe, and this applies to all plastic kitchenware. While some are manufactured and made suitable for microwave use, others aren’t.

That is why it is important to know what to look out for before using specific cups in your microwave oven. In fact, according to the FDA, some plastic  cups are so delicate that using them in your microwave will literally melt them.

How to Recognize Microwave Safe Symbol


Microwave Symbols: Source: applianceinn.com

The microwave safe symbol is usually located directly under the container. It usually comes with 3 or more wavy lines, some have a hieroglyphic of a microwave oven but the symbol to always look out for is the wavy lines. They are quite consistent with all microwave safe container.

To check, simply turn the cup over. It might be a simple brand or a braille symbol to notify you that the cup is microwave oven safe. If your cup doesn’t come with that symbol, it would be best to avoid using it in your microwave oven.

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Why Aren’t All Plastic Cups Microwave Safe

From the above, not all cups are microwave safe. In fact, you either see the microwave safe symbol under your cup or you don’t. If you don’t, you shouldn’t use it in your microwave.

The reason why most plastic containers are not safe for microwave use is the presence of BPA and other harmful substances that are usually used to manufacture plastic. Over the years, Bisphenol A content in the diet has been discovered to result a lot of health conditions including low sperm count and heart diseases.

Aside from that fact, not all plastic cups will hold in a microwave oven, the heat from the cups content can cause the cup to melt, especially really light and thin cups. So when it comes to using a plastic cup in your microwave, always check for the microwave safe symbol.

On the other hand, plastic cups that have up to 50 microns in thickness are usually safe. This is majorly because the thickness of the cup reduces the chances of it seeping harmful chemicals into your food or water as the case may be.

Can you Boil Water in a Plastic Cup Using a Microwave

Most people who use plastic cups in their microwave oven usually use it to heat up water. Styrofoam and a few other plastic cups are safe for use in the microwave for specific things. Using a plastic cup to heat water up in your microwave (as long as the cup is microwave safe) shouldn’t cause any adverse effect to your cup, water or health.

Using Plastic Cup to Heat up Other Liquids

Other liquids like pasta sauce, oil or oil based drinks might not fare as well in your microwave oven. This is because the oil can easily separate from the water, and it tends to heat up much faster, causing the cup to have uneven heat in the different parts. This can result in a couple of things

  1. It can melt the plastic cup
  2. Chemicals that might not otherwise have been harmful with water based liquids will be activated with the oil and can leech poisonous and harmful chemicals into your drink.
  3. It becomes extremely hot. Lifting the cup from the microwave with your bare hands can result in burns.

BPA and Plastic Cups

BPA is a material that is commonly used in the manufacture of plastic serving kitchenware. They are used for the manufacture of most items that are used in the kitchen, feeding bottle, plastic cups, plastic plates e.t.c.

It is usually added to these utensils to harden them as well as line cans and medical equipment. A person will usually get exposed to BPA and its accompanying risks when they use these BPA based containers in extreme heat. The heat activates the poison in the BPA causing it to leech harmful chemicals into the cup or food.

Unfortunately, this means that most of these utensils are not safe for use in your microwave. In addition, over the years, the presence of BPA in kitchenware has been discovered to cause a lot of harm to the body including heart and reproduction issues.

Ingesting BPA in your diet once doesn’t necessarily expose you to harm. Usually, you will pass any BPA out as liquid waste when consumed. On the other hand, continuous exposure to BPA is very dangerous to the health.

Microwave Safe Recycled Plastic Cup

Usually, recycling plastic usually have a number range. There are plastics recycled from numbers 1-7 and not all these numbers are safe for use in your microwave.

In fact number 5 is the safest; and while 1,2 and 4 are somewhat safe as well, you should only use them when you have no choice. 3, 6 and 7 are considered extremely dangerous to the health.

Below are the recycling numbers and their contents

plastic recycling number

Plastic Recycling Numbers. Source: Eartheasy

Number 1- Polyethylene terephthalate (PTE)

It has a relatively low risk level and is usually used to make beer and ketchup containers, peanut butter containers and some water bottles.

Number 2- High density polyethylene (HDPE)

It also has a low risk level. It is usually found in household cleaning containers, shampoo, detergent, bleach

Number 3-  Polyvinyl chloride (PVC)

Extremely dangerous, especially when burnt. This is usually found in windows, shampoo, cooking bottles

Number 4-  Low density polyethylene (LDPE)

Moderately safe. It is usually found in furniture, shopping bags, frozen foods

Number 5- Polypropylene (PP)

It is considered the safest option for microwave safe containers and is extremely resilient because it does not melt easily. It is usually found in medicine bottles and their caps, straws, tomato sauce e.t.c

Number 6- Polystyrene (PS)

Despite the fact that is quite dangerous, it is still being widely used. It has been discovered to be a major cause of cancer. It is usually found in egg cartons, disposable plates e t.c

Number 7- Polylactic acid and others (PLA)

Also known as a hormone disruptor. It is not healthy for use in your microwave. It is usually found in nylon, computer cases, sunglasses and water bottles.


In this article, we considered the topic “are plastic cups microwave safe.” For a plastic cup to be considered microwave safe, it will usually come with a microwave safe symbol, directly on the bottom part of the microwave.

This symbol will usually look like 3 or more wavy lines and this will mean that you can use such cup in the microwave. While some cups can be used in the microwave, you shouldn’t use them unless you have no other option.

This is because most plastic containers are produced with unhealthy materials. And a lot of microwave safe containers have traces of such materials in them. Try to avoid using any form of plastic in your microwave oven if you can.

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