How Long Does Chopped Onion Last?

A whole, unpeeled onion kept in a cool, dark, dry spot can last several weeks to a couple of months, but chopping it changes that calculation entirely — cut onion exposed to air and moisture in the fridge holds for only about 7-10 days in a sealed container, since the cut surfaces both dry out and pick up bacteria far faster than an intact bulb protected by its papery outer layers. Sliminess, a sour or unusually pungent smell beyond onion's normal sharpness, or visible mold are the real signs a container of chopped onion has turned, distinct from the normal darkening cut onion develops at its edges after a day or two.

Storing chopped onion in a genuinely airtight container, rather than a loosely folded bag, matters more here than for many vegetables, since onion both releases its own moisture as it sits and readily absorbs odors from other food nearby — a container that seals well keeps both problems in check and also keeps the rest of the fridge from smelling like onion. A bag or container with any visible liquid pooling at the bottom is a sign the onion is breaking down faster than normal and is worth using soon or discarding rather than pushing toward the far end of that 7-10 day window. Buying only what a week's worth of cooking actually needs, and chopping just before use rather than days in advance, sidesteps this shorter countdown entirely for anyone who cooks with onion often enough to make that practical.

See Chopped Onion's full storage & shelf-life guide (with spoilage signs) →