Microwave Safe Utensils: What You Can and Cannot Put Inside
Can we put glass in a microwave oven? What about a steel bowl, aluminium foil or a plastic box? The answer depends on the material and on the mode you use. This guide explains which utensils are microwave safe, how to read the microwave safe symbol, and what changes when you use grill or convection.
Updated 11 November 2026
Quick list: safe and not safe in microwave mode
Safe in microwave mode:
- Heat-resistant glass bowls and jugs (borosilicate)
- Plain ceramic, stoneware and china without metal paint
- Plastic marked microwave safe
- Silicone moulds and lids
- Paper towels, plain paper plates and butter paper for short heating
Not safe in microwave mode:
- Steel and aluminium pots, steel tiffins and pressure cooker parts
- Aluminium foil sheets and foil takeaway trays
- Plates and cups with gold, silver or metallic rims
- Thin takeaway boxes, polythene bags and old cracked plastic
- Melamine crockery, unless the maker says it is microwave safe
- Brown paper bags, newspaper and anything with staples or wire ties
Can we put glass in a microwave oven?
Yes, most glass is fine, and heat-resistant glass is the best microwave cookware. It lets the waves pass, does not stain, and you can see the food.
Take care with:
- Thin decorative glass or crystal, which can crack with sudden heat.
- A thick glass bowl straight from the fridge into a hot oven. Let it come up to room temperature or use a lower power.
- Glass with metal paint or a metal rim.
Thick glass bowls are safe as long as they are heat-resistant. A cracked or chipped dish should not be used.
Can we use steel utensils in a microwave oven?
Not in microwave mode. Steel reflects microwaves, so the food inside a steel bowl stays cold, and thin edges or a loose lid can spark and damage the magnetron cover.
The exception is grill-only and convection-only modes. In those modes the oven heats with a hot rod or hot air, not microwaves, so the metal rack, metal cake tins and steel trays that come with the oven are fine. In combi mode, follow your manual, because many ovens still send microwaves during combi cooking. Convection models such as the Kenwood MWP29.000BK 30 Litre Convection Microwave Oven and Haier HMW-30AF (AFR/AFS) 30 Litre Air Fryer Microwave Oven come with their own racks for this reason.
Can I put aluminium foil in a microwave oven?
In microwave mode, avoid it. Crumpled foil and foil trays can spark and even start a small fire. Some manuals allow very small, smooth strips of foil to shield thin parts of a chicken from overcooking, kept well away from the walls, but if your manual does not say so, do not do it.
In grill or convection-only mode, foil can line a tray to catch drips, just as in a normal baking oven. Never cover the oven floor, vents or the mica sheet on the side wall with foil.
Which plastic is microwave safe?
Use only plastic marked microwave safe. Common signs are a picture of a microwave with wavy lines, or the words microwave safe on the base. Code 5 (PP) containers are usually designed for reheating.
Even safe plastic should be used for reheating, not long cooking of oily or very sugary food, because fat and sugar get much hotter than water and can warp the box. Do not reuse thin takeaway or yoghurt tubs, and do not let plastic cling film touch the food. Move curry into a glass or ceramic bowl if you plan to heat it for more than a couple of minutes.
What does the microwave safe symbol look like?
There is no single world standard, but you will usually see one of these on the base of a dish:
- A small microwave drawn with wavy lines inside
- Wavy lines with a plate or bowl
- The words microwave safe or microwaveable
A symbol with a cross through it means not for microwave use. Oven safe is not the same as microwave safe: an oven-safe metal tray is fine in convection mode but not in microwave mode. If a dish has no mark, use the water test below.
Which utensils to use in grill, combi and convection mode
The mode you choose changes the rules, because only microwave mode uses microwaves alone.
- Microwave mode: glass, ceramic, silicone and microwave-safe plastic. No metal.
- Grill mode: the metal rack that came with the oven, plus heat-proof glass or ceramic. No plastic, because the top heater can melt it.
- Convection mode: metal cake tins, steel trays, oven-safe glass and silicone. No plastic.
- Combi mode (microwave plus grill or convection): heat-proof glass, ceramic or silicone is the safe choice. Use the oven's own rack only if the manual allows it.
Grill models such as the Dawlance DW-393 G 23 Litre Grill Microwave Oven and Homage HDG-2313B 23 Litre Grill Microwave Oven include a rack for grill mode. If you mostly bake, a convection microwave oven lets you use ordinary metal bakeware.
Simple test: is this dish microwave safe?
- Put the empty dish in the microwave next to a glass cup of water.
- Heat on High for 1 minute.
- Touch the dish carefully.
If the water is warm and the dish is cool, the dish is microwave safe. If the dish is hot, it is absorbing microwaves and should not be used. Do not try this test with anything metallic.
Best microwave cookware to buy
- A set of heat-resistant glass bowls with vented lids for reheating and cooking rice
- A microwave cover lid to stop splashes
- A glass or ceramic cake dish for mug and bowl cakes in a solo oven
- A silicone cake mould, which works in microwave, combi and convection modes
- A metal baking tin for convection-only baking
The turntable plate that came with your oven is made for it. A replacement must match the size, for example 28.5 cm on the Haier HMW-26MBH 25 Litre Solo Microwave Oven or 36 cm on the Samsung MG40DG5524AT 40 Litre Grill Microwave Oven. For cleaning tips see the microwave safety and cleaning guide.
