Can I use oven cleaner or a scourer inside the microwave?

Skip the scourers: the FDA recommends mild soap and water and no abrasive pads or steel wool. Use any other cleaner only if your microwave's manual says it's fine, and wipe it off thoroughly afterwards.

How do I get rid of a burnt popcorn smell?

Run the lemon steam again, leave the door open for a few hours to air it, then leave a small bowl of baking soda inside overnight with the microwave switched off.

The paint inside is peeling. Is that a problem?

Don't keep using it until you've checked the manual or asked the manufacturer. Peeling or rusty interiors need a look from someone who knows the model.

How do I stop it getting so messy?

Cover food while it heats, with a microwave cover or an upturned plate. Soups, sauces and beans stop painting the ceiling.

How to clean a microwave in 5 minutes

Let steam do the scrubbing. Heat a microwave-safe bowl of water with a few lemon slices or a splash of vinegar until it boils and fogs the window, leave the door closed for a few minutes, then wipe: dried-on splatters slide off a damp cloth. Total hands-on time is about five minutes. The only thing to respect is the heat, because the bowl and the steam come out very hot.

What you’ll need

A microwave-safe bowl or jug, glass or ceramic with no metallic trim.
About a cup of water (roughly 250 ml).
Half a lemon, sliced, or a couple of tablespoons of white vinegar. No lemon or vinegar? Plain water still makes steam.
A dry tea towel or oven glove to lift the bowl out.
A soft sponge or microfiber cloth and a drop of washing-up liquid.

Nothing metal goes in, and that includes the spoon you used to stir. The FDA is clear that metal pans and foil don’t belong in a microwave.

The five-minute steam clean

Fill the bowl. Water plus lemon or vinegar. According to the FDA, adding something to water before heating it also reduces the risk of it suddenly boiling over when disturbed.
Heat it. Start with about 3 minutes on high and keep an eye on it. Once the water’s boiling and the window has steamed up, stop. Don’t keep it running longer than it needs.
Wait with the door shut. Another 3 to 5 minutes. This is when the steam softens the grease.
Lift the bowl out carefully. Tea towel or oven glove, face back from the door as you open it, and no rushing across the kitchen with it.
Take out the turntable and roller ring if there is one. Wash them in the sink like any other dish.
Wipe the inside. Ceiling first, then the walls, back and floor. If anything resists, dip the sponge in the lemony water and go again.
Do the door, inside and out, with a drop of washing-up liquid on the cloth, then a plain damp cloth. Get into the edges, where grease likes to hide.
Dry and reassemble. Leave the door open for a few minutes so the moisture escapes.

Mess by mess

Mess	What works
Fresh splatters	A damp cloth straight away, no steam needed
Greasy ceiling	Lemon or vinegar steam, then a damp cloth
Yellowed turntable	Soak in hot soapy water in the sink
Burnt popcorn or fish smell	Lemon steam, door open to air, baking soda bowl overnight with the power off
Old baked-on crust	Steam again; no knives, steel wool or scouring pads
Outside and keypad	Lightly damp cloth with mild soap; never spray straight onto the controls

Got a combination microwave with a grill element or a convection fan? The steam method still works, but wipe around the element gently rather than scrubbing it, and check the manual for anything it says about the grill area or any special interior coating.

Safety bits worth knowing

A microwave is a simple machine, but the FDA highlights a few things:

No abrasives. Mild soap and water for the cavity and door. Steel wool and scouring powders scratch and can damage the lining.
Check the door. If it doesn’t close firmly, or it’s bent, warped or damaged, stop using the microwave until it’s been looked at.
Keep metal out. Spoons, foil and plates with gold or silver rims stay out.
Running it empty. Some models shouldn’t be run empty. Your manual says whether yours is one of them.
Superheated water. Plain water heated on its own can erupt when you move it. Don’t heat it longer than the manual suggests, and handle the bowl gently.

How often to clean it

A microwave that gets used daily is happiest with little and often:

Splatter happens: damp cloth while it’s still easy.
Weekly: the steam clean from this guide. Five minutes.
Monthly: turntable and ring in the sink, plus the outside and the top of the microwave, which collects dust and cooking grease.

The weekly steam clean slots neatly into a short burst. If you like breaking the house into small chunks, the 15-minute cleaning routine has ideas for what to pair it with. And the microwave is just one corner of the kitchen: how to keep your kitchen clean every day covers the full routine, and the stove has its own guide, how to clean your stove and oven.