Can You Microwave Metal? Foil and Stainless Steel Rules

Written by Sara Ibrahim. Sara researches home and kitchen products for Cupindy.

Published October 2026 · Last reviewed October 26, 2026 · Cupindy is not affiliated with any brand on this page.

The answer has two parts because the people who write the rules don't agree. The FDA, GE, Whirlpool and Maytag lean hard toward no. Amana says foil “and some metal can be used” in its ovens. Below is what each says about foil, and why most stainless steel stays out.

As an Amazon Associate we earn from qualifying purchases.

Why Does Metal Spark in a Microwave?

Caroline Ross, a materials science professor at MIT, wrote in 2010 that it is “counterproductive to put something metallic inside your microwave oven if you want to heat it up.” Microwaves pass through glass, paper, ceramic and plastic. Metal bounces them back, so the food behind it heats unevenly, and the FDA says it may damage the oven.

Sparks are the other problem. They start where metal is thin, wrinkled or comes to a point. The USDA says arcing happens when microwaves “react to gold paint on dishes, twist ties and other metallic materials.” So the foil rules below all ask for small, smooth, flat pieces.

What goes in the microwave, at a glance:

If you are replacing foil or a metal bowl, these are the four we would pick. Each listing was read on October 26, 2026.

As an Amazon Associate we earn from qualifying purchases.

Can You Put Aluminum Foil in the Microwave?

Aluminum (tin) foil can go in sometimes, in small amounts, if your microwave's manual says so. GE, Amana and the USDA allow smooth foil to shield parts of the food that cook too fast, such as turkey wing tips. Whirlpool says to follow your manual and, if the manual is silent, not to use foil at all.

The foil rules oven makers print

• New and smooth. The USDA: “Use new, smooth foil only. Wrinkled foil can cause arcing (sparks).”
• A little, pressed flat. The USDA says to “Cover no more than 1/4 of the food with foil.” GE adds: “No foil should be sticking up or out away from the food product.”
• An inch of space. “Do not place the foil closer than one inch from the oven walls,” says the USDA. Amana counts the door as a wall too.
• Never wrap the food. Maytag: “Don't attempt to microwave food wrapped in aluminum foil.”
• Turntable in. Maytag and Amana both say “Always use the turntable.”
• Stop at the first spark. Whirlpool says to “immediately end use if you see or hear sparks.”

Past those six points the makers part ways. Amana is the most relaxed. Maytag ends its guide with “When in doubt, avoid placing any kind of metal, even aluminum foil, in your microwave.” Whirlpool says “Always defer to your user manual,” and if the manual doesn't mention foil, to “avoid using it in the appliance at all.” We go with the manual. If yours says nothing about foil, leave it out.

Foil Trays, Takeout Containers and Aluminum Pans

Here the rules get stricter. The USDA says: “If the microwave oven has metal shelves OR a metal turntable, don't microwave food in foil containers or metal pans.” Maytag goes further for every oven: “It is also not recommended to use aluminum bowls or trays inside your microwave.” Amana lists disposable containers with metal rims as unsafe, and the USDA adds takeout containers with metal handles and metal twist ties.

Tip the leftovers onto a plate or into a glass dish. And if you only wanted foil to cover the plate, a vented cover does that with no metal at all.

As an Amazon Associate we earn from qualifying purchases.

Using foil somewhere else? The rules change with the appliance. See foil in the oven, foil in an air fryer, and whether aluminum cookware is safe to cook with at all.

Can You Microwave Stainless Steel?

Most stainless steel should stay out of the microwave: mixing bowls, pots, cutlery, lunch boxes and travel mugs. The only exception is a container its maker sells and labels as microwave safe, used exactly the way the label says.

GE says: “Metal cookware should not be used in a microwave.” The FDA tells you to “Use microwave safe cookware specially manufactured for use in the microwave oven.” Even Greenvyne, an Australian company that sells stainless containers it calls microwave safe, says in its own FAQ that “most stainless steel is not microwave safe.”

How to Tell if a Stainless Container Is Microwave Safe

We found no government or appliance-maker advice that approves stainless food containers in general. What follows is what two container makers, Greenvyne and Elephant Box, say about their own products. Treat it as their claim, not our endorsement.

• The label comes first. Elephant Box says only certain named ranges of its boxes are microwave safe, not all of them.
• Shape matters. Greenvyne builds its microwave line with rounded corners and a controlled wall thickness. Both makers say a dented box should not go in.
• One at a time. Elephant Box says one box, not touching the walls or a rack.
• Low power, short time. Both put the ceiling at 1,000 watts. Greenvyne says to reheat in 60-second bursts.
• Lid off, food in. Elephant Box says to remove the lid first, and Greenvyne says a container should never go in empty.

No microwave-safe label on the box? Assume it is not microwave safe.

Yeti Tumblers, Thermoses and Travel Mugs

No. A double-walled steel mug is metal cookware under every rule on this page. Warm the drink in a ceramic mug and pour it back. For a lunch box you can heat at work, glass does it with no conditions.

As an Amazon Associate we earn from qualifying purchases.

What to Do if Metal Sparks in Your Microwave

• Stop it straight away. The USDA says to “turn off the oven immediately to end the sparks.”
• Take the metal out with an oven mitt. It may be hot.
• Don't try again with the same piece. A spark usually means an edge lifted, the foil was creased, or it sat too close to a wall.
• Look at the walls. If you see burn marks or pitting inside, stop using the microwave and contact the maker's service line.

What to Use Instead of Metal

Glass and ceramic. The FDA says “Glass, paper, ceramic, or plastic containers are used in microwave cooking because microwaves pass through these materials.” Look for the mark on the bottom first; our guide to microwave-safe symbols shows what each one looks like.

For glass, read can you microwave glass before you trust an old jar. For plates, our microwave-safe dinnerware picks cover sets that skip the trim. Gold and silver edges are their own problem: Whirlpool lists “objects with gold or silver trim or a metallic glaze” among the things to keep out, and our guide to whether porcelain is microwave safe explains why.

Frequently Asked Questions

How We Checked

On October 26, 2026 we read the FDA, USDA, GE, Whirlpool, Maytag and Amana guidance, an MIT Q&A, and two stainless container makers' guides. Product facts come from each Amazon listing, checked the same day. We did not test metal in a microwave, and no brand saw this page before it went up.

Sources (opened October 26, 2026). Product facts come from each Amazon listing on the same date.

• U.S. Food and Drug Administration: Microwave Ovens
• USDA Food Safety and Inspection Service: Cooking With Microwave Ovens
• GE Appliances: Using Metal or Foil in the Microwave
• Whirlpool: Can You Microwave Aluminum Foil?
• Whirlpool Product Help: What Shouldn't Be Used in a Microwave
• Maytag: Can You Put Aluminum Foil in the Microwave?
• Amana Product Help: Can Metal or Aluminum Foil be Used in the Microwave
• MIT School of Engineering: Why can't we put metal objects in a microwave? (November 2, 2010)
• Greenvyne: Can You Microwave Stainless Steel? (maker)
• Elephant Box: Microwaving Metal (maker)

Pyrex, Vtopmart, Tovolo, GE, Whirlpool, Maytag, Amana, Yeti, Greenvyne and Elephant Box are trademarks of their owners and are named here only to identify their products. Listings change; check the listing before you buy.