Frequently Asked Questions About Mason Jars and Lids

Mason jars are endlessly useful, but a few questions come up again and again. Here's what you need to know to use yours safely and confidently.

Are Mason jars dishwasher safe? Yes, though we recommend hand-washing to protect the lids and seals from detergent wear over time.

Are Mason jars microwave safe? Generally yes, but keep an eye on them. Glass reacts to heat, so avoid microwaving for more than 5 minutes, remove any metal lid first, and never microwave a frozen jar.

Can I pour boiling water into a Mason jar? Yes, but make sure the jar is at room temperature first; a cold jar meeting boiling water is a recipe for cracking.

Can I put my Mason jar in the oven? No, Kacey Christian from the National Center for Home Food Preservation says oven temperatures are too inconsistent and dry, and the risk of shattering is real.

How long will food last in a Mason jar? Properly sealed and stored in a cool, dark place, canned food holds its quality for 12 to 18 months, according to the National Center for Home Food Preservation. Check seals regularly and rotate by date.

What sizes do Mason jars come in? From a 4-ounce quarter pint up to a 64-ounce wide mouth half gallon; there's a size for nearly anything. Find your jar's size →

Are Mason jars recyclable? Yes, but separate the glass from other recyclables since it can shatter. Better yet, sterilize and reuse!

Do I need to leave space in the jar? Yes, generally about an inch of "headspace" between food and the lid for a proper seal, though this varies by what you're storing.

What causes Mason jars to break? Hairline cracks, over-tightened lids, sudden temperature changes, old age, overfilling, or too much pressure.

What if my lid gets stuck? Run it under hot water for 30 seconds to help it expand, or use rubber gloves for extra grip. Skip the knife! It's not worth the risk.

Have more questions? Join our newsletter or contact us anytime.

Ready to put a few jars to work? The reCAP Lids Starter Set gives you a lid for pouring, spraying, and storing — everything you need to get more out of the jars you already have. Shop the Starter Set →

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