Simple syrup keeps much longer and stays safer if you refrigerate it, so it should go in the fridge in almost all home-kitchen situations.

Quick Scoop

  • Yes, refrigerate it : A basic 1:1 simple syrup (equal parts sugar and water) is best stored in a clean, airtight container in the refrigerator to slow bacteria and mold growth.
  • Shelf life in the fridge :
    • Plain 1:1 syrup: about 2–4 weeks when made hot and stored airtight.
* Rich syrup (2 parts sugar : 1 part water): often lasts longer than standard syrup, but still belongs in the fridge.
  • Room temperature?
    • Technically possible for a short time, especially if you’ll use it within a few days, but it spoils faster and is more prone to fermentation, cloudiness, and mold.
  • Freezing for long-term : You can freeze simple syrup (often in ice cube trays) for several months; thaw in the fridge and use as normal.

Information gathered from public forums or data available on the internet and portrayed here.