Can you microwave glass?

Glass does not absorb microwaves meaningfully, so it heats only by contact with the food, which makes it the most reliable container material there is. The two failures are thermal shock and lead. Moving glass from freezer to microwave, or setting a hot dish on a cold wet surface, creates a temperature difference across the wall that soda-lime glass cannot take, and it cracks. Leaded crystal contains lead oxide which both absorbs energy and can leach, so it stays out of the microwave.

How to do it properly

1. Let frozen glass containers stand at room temperature or thaw in the fridge first
2. Use borosilicate or tempered glass where you can
3. Vent lids and never heat a sealed jar
4. Set the hot dish on a dry cloth or board, not a cold wet counter

What goes wrong

• Thermal shock cracks the dish, sometimes minutes after it comes out
• Leaded crystal heats unevenly and can leach lead
• Any chip or existing crack becomes a fracture line under heat

Other "can you microwave" questions

• Can you microwave styrofoam? It depends — Only if the container is labeled microwave-safe, and most takeout foam is not.
• Can you microwave aluminum foil? No — No — foil reflects microwaves and the edges arc, which can start a fire.
• Can you microwave plastic containers? It depends — Only ones labeled microwave-safe — cold-storage tubs are not among them.
• Can you microwave eggs? It depends — Beaten or pricked eggs, yes. A whole egg in its shell will explode.
• Can you microwave Tupperware? It depends — Yes, if that specific piece carries the microwave-safe symbol on its base.
• Can you microwave paper plates? It depends — Plain white paper plates are fine; anything with metallic trim or a foam layer is not.
• Can you microwave metal? No — No — metal reflects microwaves, arcs at edges, and can damage the oven or start a fire.
• Can you microwave breast milk? No — No — microwaves create hot spots that scald a baby even when the bottle feels cool.
• Can you microwave takeout containers? It depends — Only if the container is marked microwave-safe — most are not, and metal-handled ones never are.
• Can you microwave cardboard? It depends — Plain dry cardboard is usually fine briefly; anything with glue, staples, wax or foil is not.
• Can you microwave water? It depends — Yes, but very clean water can superheat and erupt when you move the cup.
• Can you microwave ceramic? It depends — Yes for plain glazed ceramic; no if it has metallic trim or is unglazed and porous.