What Happens If You Microwave Nothing?

Have you ever had one of those days where things just constantly slip your brain? I tried to pop my coffee into the microwave to reheat, only to forget to actually put the coffee in. Then I wondered: what happens if you microwave nothing?

Did I have anything to be concerned about, or was it simply something to laugh at myself for and move on? I figured if I had the question, someone else might too! So, let’s talk about what happens when you fire up the microwave without anything in it.

what happens if you microwave nothing dinners done quick featured image

Is Running Your Microwave Empty Bad?

The short answer is yes, running your microwave empty with nothing inside it is considered bad. It’s likely to damage your appliance, and if it’s running for an extended period of time can actually cause the microwave to be destroyed completely.

While of course there are things you can put in the microwave that are damaging, it turns out that nothing at all can ruin your microwave just the same!

Speaking of things that can damage your microwave, learn more about putting aluminum foil in the microwave and what can happen.

Why is Microwaving Nothing Bad for Your Microwave?

When you microwave nothing, this means there isn’t anything to absorb the electromagnetic waves that normally heat your food. The result of this is that the waves bounce around the cavity of the microwave, reflecting back and not dispersing.

These stagnant waves are actually capable of damaging your unit, all the way up to the point that it’s completely ruined and must be replaced. In fact, appliance makers Wolf & SubZero note that there is no troubleshooting advice for a microwave that’s been damaged from cooking nothing.

If this sounds familiar to you, I bet a repair or replacement are in your future!

If you end up going the replacement route, learn about 7 ideas for what to do with an old microwave.

How Long Can You Run a Microwave Empty?

To avoid severe damage, the longest a microwave can be run empty is approximately 5 minutes. This may vary by specific brand and model, amount of shielding on the microwave, and if the unit has any prior damage to it.

Limiting your cook cycle to 5 minutes should help prevent damage from overheating, and is a good practice to follow with any microwave cooking. Even if you’re actually heating something, it doesn’t hurt to check in along the way.

Do Microwaves Explode When Empty?

Microwaves do not typically explode when they are run empty. However, they are apt to melt or catch fire after a period of time. While the risk of flying shrapnel is low, the fire can damage your appliance, kitchen, and your electrical system.

With all that pent up energy having nowhere to go, it reverts back to your microwave’s magnetron which produces the electromagnetic waves to begin with. Once that piece is damaged, melted, or burned, your microwave is ruined and will no longer heat food.

Note that this all only applies if the microwave is actually in use. If your unit is not currently cooking, there’s no need to keep anything inside of it during the downtime. Waves literally only fly once the microwave is programmed and started.

If you’re curious, check out how hot a microwave gets during the cook cycle for more information.

How to Tell if Your Microwave Was Damaged By Running it Empty

  1. Place a cup of cool or room temperature water in a mug or another microwave safe container
  2. Set your microwave for 45-60 seconds
  3. Check the temperature of the water (stick your finger or a thermometer in it)
  4. If the temperature has not increased, your microwave was damaged and no longer works
woman placing a cup of water in an empty microwave

Of course, this is assuming that you didn’t run your microwave empty for long enough to cause visible damage such as burn marks. Please only use this process to check for empty use damage on a microwave that is in seemingly good shape otherwise.

If you notice a burning smell, immediately shut the unit off.

Can You Fix a Microwave That Was Damaged By Running With Nothing In It?

You can fix a microwave that was damaged by running with nothing in it, but it’s generally not worth it.  The cost of repairs considering parts and labor will range between 50-100% of the cost of a new microwave, depending on style and brand.

With the average cost of a magnetron ranging from $100-$200 and that being the main part that will need replacing, you’re better off getting a new one. Not to mention, while that’s the primary fix, other parts of the microwave may be warped, melted, or otherwise damaged as well. So, consider that the bare minimum expectation for repairs.


So, what happens when you microwave nothing? Well, if you caught your mistake in a few seconds or minutes, probably no harm done. If your microwave runs empty for an extended period, you’ll ruin the microwave and it has the possibility of setting on fire.

Always try to double check that your food is in the appliance before hitting the start button. Mitigate issues by setting the cook cycle for a few minutes at a time so you’ll catch your blunder sooner than later.

If your appliance does get damaged, make sure to repair or replace it so you won’t cause further damage to your kitchen.

Alternatively, you could be ready to purchase a new oven. We reviewed the top microwaves under $100, so you can cook without breaking the bank.

Katie Vine