How do I clean a phone properly without damaging it?

A slightly damp microfibre cloth for the screen, a soft dry brush for the grilles, and a wooden toothpick for the charging port. What ruins phones is alcohol, kitchen cleaner and compressed air.

Difficulty: beginner
Time: 15 min
Read: 4 min
Safety: caution

Short answer

Power the phone off and take the case off. Wipe the screen and back with a microfibre cloth barely dampened with water — wrung out, not wet. For grease, a wipe rated for screens is acceptable occasionally. Brush the speaker and microphone grilles with a soft dry brush. Clear the charging port with a wooden or plastic toothpick, gently, with the phone facing down so debris falls out. Let it dry fully before charging.

Two things get damaged by bad phone cleaning: the oleophobic coating on the screen, which is what makes it feel slick and resist fingerprints, and the seals and contacts around the ports. Both are damaged by exactly the products people reach for — alcohol wipes, glass cleaner, and kitchen spray. The coating cannot be restored once it has gone.

Safety

Never spray any liquid directly onto a phone, never use compressed air into the ports or speaker grilles, and never put anything metal into the charging port. Compressed air drives moisture and debris further in and can damage the speaker membranes. A metal pin in a charging port shorts contacts and destroys them. Unplug the phone before cleaning it, and let it dry fully before charging.

Step by step

Power off and remove the case.The case hides most of the actual dirt, and a powered-off phone means a wet patch cannot register as a touch or short anything. Clean the case separately in warm soapy water and dry it completely before it goes back on.
Use a microfibre cloth, barely damp.Water on a microfibre cloth, wrung out until it feels only slightly cool, removes almost everything. Wipe in one direction rather than circles. This is what phone manufacturers themselves recommend and it is enough for daily cleaning.
Avoid alcohol, glass cleaner and kitchen spray.These strip the oleophobic coating. Once it is gone the screen feels draggy, shows fingerprints far more, and a screen protector becomes the only way to get the feel back. Disinfectant wipes rated by the phone manufacturer for screens are the exception and are fine used occasionally, not daily.
Never use paper towel or tissue.Wood-fibre paper is abrasive at the scale that matters to a coating, and it leaves lint in every crevice. Keep two microfibre cloths — one for the phone, one for glasses and screens generally.
Brush the grilles rather than blowing into them.A soft dry brush — a clean, dry, soft toothbrush or a make-up brush — lifts dust out of speaker and microphone grilles. Angle the phone so debris falls away. Compressed air pushes it in and can rupture a speaker membrane.
Clear the charging port with wood or plastic.Pocket lint compacts at the bottom of a charging port and is the most common reason a cable feels loose. With the phone off and pointing downwards, work a wooden toothpick gently around the inside and hook the compacted lint out. It comes out as a surprisingly solid plug. Never metal, never force.
Clean the camera lenses last and carefully.A lens cloth, dry, with any grit blown off first by simply turning the phone over and tapping. Grit dragged across a lens cover scratches it permanently, and a scratched lens shows as haze and flare in every photograph.
Let it dry completely before charging.Both platforms detect moisture in the charging port and refuse to charge, which is a protection rather than a fault. Give it an hour in a warm, ventilated place rather than trying to hurry it, and never use a hairdryer.

If it doesn't work

Screen feels draggy and shows fingerprints badly

Cause: The oleophobic coating has worn or been stripped by cleaning products — Fix: It cannot be restored. A tempered glass screen protector has its own coating and returns the feel completely, which is the practical answer.

Callers cannot hear you clearly

Cause: A blocked microphone grille, often at the bottom edge and sometimes on the back — Fix: Brush all the grilles. Phones have two or three microphones and blocking one degrades noise cancellation rather than muting you, which makes it harder to notice.

Speaker sounds muffled or quiet

Cause: Dust in the earpiece or speaker grille, or a case covering it — Fix: Brush gently, check the case cutouts line up, and try a call on speaker to compare the two speakers. Do not poke anything into the grille.

The phone says liquid detected in the connector

Cause: Moisture in the port, sometimes days after it got wet — Fix: Do not charge, do not use a hairdryer, do not put it in rice. Leave it port-down in a warm ventilated place for several hours. Use wireless charging in the meantime if the phone supports it.

Keeping on top of it

Wipe the screen and back with a damp microfibre cloth (Weekly)
Wash the case in warm soapy water and dry fully (Monthly)
Brush out the speaker and microphone grilles (Monthly)
Clear compacted lint from the charging port (Every few months, or when the cable feels loose)
Check the screen protector for lifting edges and cracks (Monthly)
Wipe the camera lens covers with a dry lens cloth (Before anything you want to photograph properly)

Questions people ask

Can I use a UV steriliser box?

They do sanitise, and they do not touch the coating. Whether it is worth it is a personal question; a damp microfibre cloth removes the visible dirt that a UV box leaves in place.

How dirty is a phone really?

Dirtier than most people expect, because it goes everywhere and is handled constantly. That is an argument for cleaning it weekly rather than for aggressive chemicals — regular gentle cleaning beats occasional harsh cleaning by a wide margin.

What about the inside of the case?

It is usually the dirtiest part of the whole assembly, and grit trapped there scratches the back of the phone. Wash it properly and check for grit each time you take it off.

Is it safe to clean a cracked screen?

Very carefully, with a barely damp cloth, and no pressure. Do not let liquid reach the crack — it will wick into the display. Tape over the crack until it is repaired.