How To Cut Onions Without Crying: Pros Share 9 Easy Hacks

Many of us love onions. In fact, the average American eats about 22 pounds of onions per year! But what we don’t love is the way onions make our eyes burn and tear when we slice into them. That’s why we asked food scientists how to cut onions without crying. Keep scrolling for their genius hacks!

Why do onions make me cry?

Onions have a natural defense mechanism that prevents predators from eating them and helps them grow to maturity. When we cut an onion, we essentially rip apart its cellular structure, causing a cascade of chemical reactions, says Abbey Thiel, creator of the YouTube channel Abbey the Food Scientist.

One of these reactions leads to a molecule called syn-propanethial-S-oxide, which vaporizes into a gas and eventually comes into contact with our eyes. “After reacting with the moisture in our eyes, small amounts of sulphuric acid are produced which irritates the cornea and leads to the tears.” While you may not be able to completely eliminate tearing up, there are several tricks you can use to beat the burn next time you’re chopping onions for a meal.

See Abbey the Food Scientist discuss the science behind the crying — as well as some ways to prevent it! – here:

How to cut onions without crying: 9 smart strategies

1. Sharpen your knives

The compounds that make your eyes burn and tear up are released when you cut into the onion, but using a sharp knife causes less damage and releases less tear-causing compounds into the air, says “The Onionista,” Rene Hardwick, Director of Public and Industry Relations for the National Onion Association. “If you use a serrated knife or a knife that you’ve been using to cut through the wall and it’s dull, it tends to break into the cells a bit more and then more compounds come out.”

See this video from culinary scientist Jessica Gavin that mentions 7 ways to cut an onion without crying — including the sharp knife method:

2. How to cut onions without crying: Keep them cool

“We recommend that you chill an onion for 30 minutes prior to cutting into it,” says Hardwick. Cold temperatures slow down the chemical processes that release the tear-inducing compounds, delaying how quickly they happen and giving you more cutting time. So as long as you’re able to chop fairly quickly, any exposure to the compound is greatly reduced.

See this video from The Travelling Scientist that demonstrates this tip in action (along with some others):

3. Cover your eyes

If you wear contact lenses, you may have noticed that cutting onions doesn’t affect you as severely as it does someone who doesn’t wear them. “Contact lenses act like little shields and protect your eyes from the irritating gas,” says Thiel. You can replicate this effect — and even improve on it — by wearing onion cutting goggles. “You’re basically shielding your eyes from the irritating gas because it can’t enter through the goggles.”

See Chef Matt of I Want to Cook demonstrate onion cutting goggles in this YouTube video:

4. Blow the fumes away

Setting up a fan near your cutting area and turning it on low or cutting under a vent can help to prevent any tearing that occurs while you’re chopping an onion. That’s because a fan would blow much of the syn-propanethial-S-oxide away rather than allowing it to reach your eyes, while a vent would suck up the air containing the compound, says Hardwick.

London Brazil of The Evolving Table mentions using a fan or vent while cutting in this video:

5. How to cut onions without crying: Break out your bread

Though no one seems to really know the science behind this onion cutting hack, there are some that swear that it works. Simply hold a piece of day old white or wheat bread in your mouth like a giant tongue, says Linda Carucci, chef, culinary instructor and author of Cooking School Secrets for Real World Cooks. while chopping the onion and it’s said to prevent crying. Carucci thinks “It sort of deflects the vaporized compound from going up into your nose.”

This video from Chop Happy demonstrates the bread hack in action:

6. Cut it correctly

Some say to leave the stem intact and others say leaving the root intact is the trick to preventing your onion-cutting tears. Carucci prefers cutting the root off and leaving the stem end intact, and then slicing the onion in half and then cutting each half in half again, always cutting through the stem rather than across it. If you’re right-handed, she then recommends cutting slices in the onion perpendicular to the board with the rounded end of the onion facing away from you, the flat end facing down onto the cutting board and the stem in your left hand, without cutting through the stem. Finally, with your knife perpendicular to the cuts you just made, cut through the onion from right to left all the up to the stem.

“One reason this may work is because you’re damaging the onion membranes less when you cut in this way and releasing fewer compounds,” says Carucci. If you’re a leftie, reverse the directions.

See Camy Arriola of The Plant Based Kitchen demonstrate cutting an onion without severing the root here:

See Russell Jackson demonstrate cutting the root off in this Chow Hound video:

7. How to cut onions without crying: Use the wet paper towel trick

Some experts claim that placing a wet paper towel next to the cutting board while you’re chopping an onion will attract the syn-propanethial-S-oxide, drawing it into the towel rather than letting it float through the air up to your eyes. Some people say this doesn’t work, but the tip went viral on TikTok a few years ago — and the folks at knifemaker F.N. Sharp mention it, so we say it’s worth giving it a shot at least once to see if it works for you.

See the F.N.Sharp video that demonstrates the paper towel method here:

8. Light a candle

Place a lit candle right next to the onion on the cutting board, and begin cutting or chopping. When candles burn, oxygen molecules in the air interact with wax molecules and the wax burns. The theory behind this method is that as the candle flame burns using up the oxygen in the air around it, it also burns up the vaporized compound from the onion. “That might be one I would consider trying because of the atmospherics,” says Carucci.

Gavin mentions this in her video above, but also see this video from Smart Fox that provides an explanation:

9. How to cut onions without crying: Use your microwave

The folks at Toshiba Lifestyle say your microwave is good for helping to reduce the fumes that occur after you cut into an onion. They recommend heating an onion for 30 seconds in the microwave before beginning your chopping. They say, “The heat of the microwave releases the eye irritants in the onion so you can cut while avoiding tears.” If you need your onion crunchy, though, you might not want to give this method a try as heating the onion will also soften it up a bit. Dipping the onion briefly into boiling water would work in the same way.

How not to cut an onion to avoid crying

One way you may have hear of to avoid coming into contact with the gas produced by cutting an onion, is to do your chopping with the onion under cold running water or submerged in a bowl of cold water, but Thiel doesn’t really recommend them. “These methods would work because any of the irritating gas that’s produced gets flushed away by the water,” says Thiel, but notes that “both these methods sound like an awfully good way to accidentally cut yourself.” If you do choose one of these methods, we advise caution.