How to Clean a Microwave Inside, Including Grease and Smells

The steam method: how to clean a microwave from inside

This is the method worth knowing, because it does the work for you and needs nothing bought. The steam condenses on the walls and softens dried food so it wipes off instead of being scraped off.

• Step one. Half fill a microwave-safe bowl with water. Add the juice and the squeezed halves of one lemon, or a few large spoons of white vinegar. Both work; lemon smells better in the kitchen afterwards.
• Step two. Put the bowl in, close the door and run the microwave on full power until the water is properly boiling and the window has steamed up. Two to five minutes depending on your model. Add a wooden spoon or a couple of drops to keep it from superheating if your bowl is very smooth.
• Step three. Leave the door shut for another five minutes. This is the step everyone skips and it is the one doing the work. The trapped steam is what loosens the baked-on splatter.
• Step four. Open the door carefully — the steam that comes out is hot — and take the bowl out with a cloth, because it will be very hot.
• Step five. Wipe the inside with a soft cloth or sponge: ceiling first, then the side walls, then the back, then the base and last the door and its inner rim. Working top to bottom means you are not re-dirtying what you have done.
• Step six. Anything still stuck has not had enough steam. Repeat rather than scrubbing harder.
• Step seven. Wipe everything once more with a cloth wrung out in clean water, then dry it. Leftover lemon or vinegar residue smells odd when the microwave is next heated.
• Leave the door open for a while afterwards. A closed, damp microwave is exactly how a musty smell starts.

The turntable, the roller ring and the door

The glass plate gets cleaned; the ring underneath it almost never does. That ring is usually where the smell and the grinding noise come from.

• Take the turntable out and wash it like a dish. Hot water and dishwashing liquid. Let it come to room temperature before washing, because putting a hot glass plate into cold water can crack it.
• Lift out the roller ring underneath. The plastic wheel assembly the plate sits on. Food and syrup collect in it and dry solid, which is why a turntable starts to grind or judder. Soak it in hot soapy water and clean between the wheels with an old toothbrush.
• Clean the recess it sits in. The dish in the floor of the microwave where the drive coupling turns. Spills collect there and go unnoticed under the plate.
• Dry both fully before refitting. A wet roller ring picks up grit and drags.
• Do the door properly. Wipe the inner face, the frame, the rim and the little ledge along the bottom of the opening where crumbs collect. Grease and crumbs on the sealing surfaces stop the door closing cleanly, which matters more than it looks.
• Do not soak the control panel. Use a barely damp cloth on it and dry immediately. Water behind a membrane panel is a common way to kill one.
• Clean the outside vents with a dry brush. In Delhi they clog with kitchen grease and dust together, and blocked vents make the microwave run hotter than it should.

The ceiling and the waveguide cover: the one part not to scrub

The ceiling collects more splatter than any other surface because everything that pops upwards lands there and bakes on. It also holds the one part of a microwave interior that has to be treated carefully.

• Find the waveguide cover. It is a thin rectangular panel, usually a light beige or grey, sitting flat against the ceiling or one side wall. It is made of a card-like or mica-type material, not metal or glass. It covers the opening through which the microwave energy enters the cavity.
• Never soak it, never scrub it, never remove it. It is designed to be left in place. Soaking makes it swell and disintegrate, scrubbing wears through it, and prising it off exposes the opening behind it. If yours is not obviously a removable, washable part, treat it as fixed.
• Clean it gently. A soft cloth, barely damp, wiped lightly, then dried. That is the whole method. Steam from the bowl will already have softened most of what is on it.
• Do the rest of the ceiling normally. A cloth wrung out in warm soapy water. If reaching up is awkward, lay the cloth flat on your palm and press it against the ceiling to hold the moisture there for a minute before wiping.
• Look at the condition of the cover while you are there. If it is charred, blistered, cracked, swollen or has burnt holes, stop using the microwave and have it looked at. A damaged waveguide cover lets grease reach the part behind it and is a known cause of arcing — the sparking and popping people describe as their microwave sparking inside.
• Never run a microwave with the cover missing. If it has fallen off or someone has removed it, do not simply carry on. It needs replacing first.

How to remove a smell from a microwave

Nearly every lingering microwave smell comes from residue you have not found yet, so cleaning first and deodorising second is the right order. If the smell survives a proper clean, one of the tricks below will finish it.

• Clean first, always. Ceiling, roller ring, the recess under the turntable and the door ledge. A smell that keeps returning usually means one of those was missed.
• Lemon steam. The same bowl of water with lemon, run for a few minutes and left to sit, deals with most cooking smells on its own.
• Vinegar steam for stronger smells. Water with a good splash of white vinegar, steamed and left for ten minutes, then wiped out. The vinegar smell itself disappears once it dries and the door is left open.
• Baking soda for a burnt smell. Burnt popcorn, burnt milk and burnt garlic are the hard ones. After cleaning, leave an open bowl of baking soda inside overnight with the door shut and the microwave switched off. Repeat a second night if needed.
• Air it. Leave the door open for a few hours in a ventilated kitchen. In monsoon humidity, a shut microwave holds a damp smell for days.
• Check outside the cavity. If the smell is there even when the door has been open, look at the vents and the top of the unit, and at whether something spilled behind or under the microwave itself.
• A smell of hot plastic or burning electrics is different. That is not a cleaning problem. Unplug it and stop using it.

What never to use, and when to stop cleaning and call someone

The inside of a microwave is a sealed metal cavity with a thin protective finish. Damage that finish and you get rust, and rust inside a microwave leads to arcing. That is why the list of things to avoid matters more here than on an oven or a hob.

• No abrasive powders or creams. Scouring powder and cream cleansers leave a scratched surface that traps food and starts to corrode.
• No metal scourers or steel wool. They strip the finish, and stray metal fibres left behind will spark the next time you run it.
• No bleach. It attacks the interior finish and the seals, and it should never be heated in an enclosed space you cook in.
• No oven cleaner or caustic spray. These are formulated for enamelled oven interiors, not for a microwave cavity, and the fumes are not something to trap in a small box.
• No knives, blades or scrapers. One deep scratch through the coating is enough to start rust.
• Do not spray anything directly into the cavity. Spray onto the cloth, not into the microwave, so nothing runs into the vents or behind the waveguide cover.
• Never run it empty. Not to dry it out, not to burn off a smell, not for any reason. With nothing inside to absorb the energy, the magnetron has nowhere to send it and can be damaged in minutes.
• Unplug it before cleaning. Simple, and it removes any chance of the unit starting while your hand or a wet cloth is inside.

Stop using it and get it looked at if: the door does not close cleanly, sits crooked or has to be pushed or held to latch; the door seal or the frame is cracked, dented or bent; a hinge or the latch is broken; the waveguide cover is charred, holed or missing; you see sparking or arcing inside; there is rust visible on the cavity walls; it hums, smells of burning or runs but does not heat; or it has been dropped. A microwave door and its seal are what keep the energy inside the box, so a damaged door is a stop-using-it matter and never a cleaning question.

When you do hand it over, say what the fault is, the brand and model, whether it is a solo, grill or convection model, and what you have already checked. Our microwave repair cost guide explains what drives the difference between a small job and one where replacement makes more sense. If the whole kitchen has built up grease, our chimney dripping oil page deals with the other main source of it, and kitchen deep cleaning covers the full job. To keep on top of it, see our kitchen cleaning habits and chimney care tips.