How to cut onions without crying: 7 tips and the right tools

To cut an onion without crying, you need to limit the irritating gas it releases: use a sharp knife and a chilled onion, cut the root last… or let a closed chopper do the work for you. Here is why onions make you cry, the 7 tips that really work and the tools that get rid of the tears.

Why do onions make you cry?

When the blade slices an onion, it breaks its cells. An enzyme called alliinase then turns sulphur compounds into a volatile gas, syn-propanethial-S-oxide. The gas rises to your eyes, irritates the nerve endings and triggers tears: it is a protective reflex. The fewer cells you crush and the less gas reaches your face, the less you cry.

7 tips that really work

1. A sharp knife. A clean blade slices cells instead of crushing them, so it releases far less gas. If your knife drags, sharpen it like a pro with a 3-stage knife sharpener.
2. A cold onion. Put it in the fridge for 30 minutes before cutting: cold slows the chemical reaction and makes the gas less volatile.
3. The root last. The base of the onion holds most of the irritating compounds. Keep it intact while you cut and remove it at the end.
4. Fresh air. Work under the cooker hood with the fan on, or near an open window: the gas is carried away before it reaches your eyes.
5. Quick work. The longer the onion sits open on the board, the more it releases. Cut in one go and put the pieces in a closed container.
6. Eye protection. Sealed goggles block the gas completely: not elegant, but foolproof.
7. A closed chopper. In a closed bowl the gas stays trapped: it is the easiest way to chop without a single tear.

Popular tricks that hardly help

Holding a piece of bread in your mouth, a match between your teeth or a spoon on your tongue: these old wives’ tricks have little proven effect. They do nothing about the gas escaping from the onion. Cold, a sharp blade and a closed container work much better.

The tools that cut onions without tears

Tool	Type of cut	Why fewer tears
Stainless-steel onion holder comb	Even rings and slices	Fast, clean cutting with fingers away from the blade
400 ml electric chopper	Finely chopped in 3 seconds	Closed bowl: the gas stays inside
12-in-1 vegetable cutter	Slices, grated, julienne, chopped	Closed 1.2 L container and very fast cutting
Manual mini chopper	Small amounts (shallot, garlic)	Chops in one movement, no contact

For perfectly even slices, the stainless-steel onion holder comb keeps the onion steady while you slide the knife between its teeth: cutting is faster and neater, and your fingers stay away from the blade. To chop without tears, the 400 ml rechargeable electric chopper turns an onion into fine pieces in 3 seconds in a closed bowl. The 12-in-1 multi-function vegetable cutter slices, grates and chops into its clear 1.2 L container, and the Press & Grind manual mini chopper takes care of shallots and garlic.

Slicing or dicing an onion: the right technique

To slice

Cut the onion in half from top to root, peel it, lay each half flat and slice: along the grain for slices that hold their shape when cooked, across the grain for slices that melt.

To dice finely

On a half laid flat, make parallel cuts without cutting through the root, then one or two horizontal cuts, and finally slice crosswise: the dice fall away on their own. The intact root holds everything together… and limits the tears.

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FAQ — Cutting onions without crying

Why do we cry when cutting onions?

Cutting an onion releases a sulphur gas, syn-propanethial-S-oxide, which irritates the eyes. The tear glands then produce tears to protect them.

Does chilling the onion really prevent tears?

Largely, yes: a cold onion releases much less gas. 30 minutes in the fridge is enough; in the freezer it could turn soft.

Which tool cuts onions without tears?

A chopper with a closed bowl, electric or manual, is the most effective because the gas stays inside. For even slices, a comb-style knife guide speeds up cutting and limits exposure.

Do sweet onions make you cry less?

Yes: sweet onions and spring onions contain fewer sulphur compounds than yellow or red onions, so they usually cause fewer tears.

All our cutting tools are in Fruit & Vegetable Cutting and Cutting & Preparation. Read also: the stainless-steel trick against garlic smell on your hands and how to peel vegetables quickly.