Here’s where my inner perfectionist had to chill out—pun intended. You cannot fill a freezer-safe jar to the brim. I know, I know, you want to maximize every inch of space, but physics will punish you. You need to leave about one inch of headspace at the top for liquids like soup, sauce, or stock.
Why? Because water expands by about 9% when it freezes. If you ignore this, you’ll find your lid popping off or—worst case—the bottom of the jar cracking off like a popped champagne cork. Been there, got the freezer burn on my thumb.
For non-liquid items (like pre-chopped onions or berries), you can be a bit more generous, but always err on the side of caution. Leave half an inch for solids, and you’ll sleep better at night.
Food Prep Life Hack: Freeze Soup & Broth in Mason Jars - Wintergreen
