Ziploc says its brand bags can be used in the microwave only to defrost or reheat, with the zipper left open. Take care with foods high in sugar or fat, which heat very quickly.
The bag should be labelled for microwave use, and you should open the zipper to vent it. Thin plastic can melt where food heats beyond what the bag is rated for, and fatty or sugary foods get hotter than water based ones. A bag without a microwave label should not go in.
| Short answer | Only if labelled microwave safe |
|---|---|
| Use for | Reheating and defrosting, as directed |
| Vent | Leave the zipper open at least one inch |
| Avoid | Bacon, fatty or sugary foods and long cook times |
| Alternative | A microwave safe bowl and cover |
How to use a bag in the microwave
- Check the packaging for the microwave safe label.
- Put the bag on a microwave safe plate or dish, not directly on the turntable.
- Leave the zipper open at least one inch so steam can escape.
- Heat in short bursts and check often.
- Open it away from your face, because steam collects inside.
What happens when you get it wrong
- Melted holes. Fat and sugar heat past the plastic rating and burn through the bag.
- Burst bags. A sealed bag swells and splits with steam.
- Uneven heat. Food in a bag often heats unevenly, with cold centers.
A microwave safe bowl with a vented cover, which gives you control.
A freezer bag for the freezer only, not for the microwave unless it is labelled.
Frequently asked questions
Are Ziploc bags microwave safe?
Ziploc says its brand bags can go in the microwave only to defrost or reheat food, with the zipper open at least one inch. Follow the label on the package.
Can you cook in a Ziploc bag in the microwave?
They are designed for reheating and defrosting, not for cooking foods that get very hot.
Can you microwave a generic zip bag?
Only if the box says so. USDA food safety guidance also warns against thin plastic storage bags in the microwave, so do not use a bag that is not labelled for it.
Can you boil in a bag in the microwave?
No. That heats the bag past its rating.