What Happens When You Put Foil in the Microwave?

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Updated August 18, 2022

If you are new to the world of microwave ovens, you may wonder what happens when you put foil in the microwave. Even the best microwaves do not enjoy having metal placed inside the cavity, but does aluminum foil count? Keep reading to find out.


  • If you put aluminum foil in the microwave oven, the edges could spark and cause a potentially dangerous fire.
  • You should not place any metal objects or pieces of metal in a microwave use aside from a pre-installed metal rack. Use a paper towel or plastic containers to cover the ingredients.
  • If your microwave catches fire, unplug it immediately, power it down, and keep the door closed until the fire burns out.

Microwaves and Metal

Microwaves can be damaged or cause physical damage to your home if you place metal objects inside of the cavity as they operate. Why? Metal does not absorb the heat created by radio waves and electromagnetic radiation, which is the primary way microwaves cook food. At best, the metal will shield your ingredients from getting cooked, as they’ll block the incoming microwaves. At worst, the metal will resist the heat but conduct related electricity, which could cause an electrical fire. If your microwave experiences a severe electrical fire, you may have to learn where to donate a microwave, as it will be damaged.

What About Aluminum Foil in a Microwave?

You should not place aluminum foil in a microwave, as the edges may spark and catch fire during the operation. Aluminum foil is rather porous compared to other metals, so it will not shield your ingredients. In other words, they’ll still cook, but the risk of fire is simply too high when it comes to pieces of foil in your microwave. Instead, cover the food with a microwave-safe lid or a paper towel.

What About Metal Racks?

Some microwaves come with a pre-installed metal rack, leading many to wonder why is there a metal rack in my microwave. There are two reasons for the inclusion of metal racks. Conventional microwave ovens include metal racks as a protective measure, as they are designed in such a way as to minimize sparks and fires. Sparks occur when metal touches certain components in a microwave, and this rack prevents this. Another reason is for microwave grill combination units, as a rack can be handy when grilling food.

What to Do if a Microwave Catches Fire

If the worst happens and your microwave catches fire, the best thing to do is to turn off the oven immediately and unplug the power cord. Do not open the microwave door. Just allow the fire to burn out of its own accord, as it will not have much oxygen to grow.

For more tips on microwave ownership, check out our helpful guide on what a waveguide cover does and how to Kasher a microwave.

Insider Tip

If you are placing any object inside of a microwave, check to see if it has metal handles beforehand.


Can you microwave stainless steel?

Stainless steel is not microwave safe, so don’t even think about it. Microwaves may be one of the most convenient appliances out there, but you should still not place covered metal, metal pans, or metal flecks inside of the cavity.

What will happen if I put foil in the microwave for only a short time?

It could still spark and catch fire even in only a few seconds, so avoid it. Instead, use brown paper bags or microwave-safe bowls to hold food items.

Can I eat food that has been microwaved with foil?

If the foil endures the microwaving process without catching fire, your food should be free of harmful chemicals and safe to eat.

STAT: Today, more than 90 percent of American homes have at least one microwave. (source)

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