A half onion typically lasts 7 to 10 days in the fridge if it’s stored in a sealed container or wrapped well. It’s best to toss it sooner if it turns slimy, smells off, or shows mold.

Storage tips

  • Keep the cut side covered tightly.
  • Store it in the fridge at 40°F or below.
  • Use an airtight container or resealable bag to reduce odor and moisture loss.

When to throw it out

  • Slimy or mushy texture.
  • Sour or unusually strong smell.
  • Any visible mold or dark, wet spots.

Practical rule

If you’re using it within a few days, you’re fine. If it’s been close to a week and it looks questionable, don’t risk it.