Phone Overheating? Causes, Risks & Fixes (iPhone & Android, 2026)

Almost every phone gets warm sometimes – that alone is rarely a problem. What matters is how hot, when, and whether it keeps happening. A phone that warms up during a long gaming session is behaving normally; one that is uncomfortably hot while sitting idle in your pocket is telling you something is wrong. This guide explains the difference, walks through every common cause with a safe fix, and flags the few situations – especially a swollen battery – where you should stop and get it looked at.

Direct answer: Phones overheat for two broad reasons. The everyday ones are harmless and fixable at home: heavy use (gaming, 4K video, navigation), charging while using the phone, direct sun or a hot car, a misbehaving background app, a software glitch, poor signal, or a thick case trapping heat. The serious ones are hardware faults – an ageing or swollen battery, liquid damage, or a board fault – which need a professional repair. If your phone is hot when you are barely using it, or the screen or back is lifting, stop using it and have the battery checked.

Normal heat vs a warning sign

Modern phones pack a powerful processor, a bright screen and several radios into a slim, fanless body, so heat is a normal by-product of work, shed through the frame. Warm to the touch is fine; only worry when the heat is out of proportion to what the phone is doing.

Normal, expected warmth happens during: gaming and AR apps; recording or exporting 4K video; navigation with the screen on; fast or wireless charging; the day or two after a big update; and using the phone as a hotspot.

Treat it as abnormal if the phone is:

• Too hot to hold comfortably, not just warm
• Hot while idle – in a pocket or on a desk, doing nothing
• Draining battery fast and running hot at the same time
• Hot in one spot, often around the camera or charging port
• Showing a temperature warning repeatedly – on iPhone, the "iPhone needs to cool down" screen (Apple's stated safe range is 0–35°C, beyond which it throttles or shuts down to protect itself)
• Visibly swelling, with the screen or back glass lifting at the edges

Common causes (and how to fix them yourself)

Most overheating has a simple explanation, and the majority of cases are solved here at no cost. Work through these before assuming the worst.

Heavy use: gaming, camera and 4K

Demanding games, AR apps, 4K recording and long navigation push the processor hard, and sustained load means sustained heat. Fix: take breaks, lower in-game graphics, drop recording to 1080p, and reduce brightness – the heat should fade within minutes.

Charging while using the phone

Charging makes heat, and so does using the phone – gaming while fast-charging stacks the two up. Fix: avoid heavy use while charging, take the case off, and charge on a hard, cool surface, not a bed or pillow.

Direct sun and hot cars

A phone left on a sunny windowsill, dashboard or beach towel overheats fast – the sealed glass body acts like a greenhouse. Fix: never leave a phone in a parked car or direct sun; move it into shade and let it cool naturally.

A rogue app hammering the processor

A single buggy app can sit in the background pegging the processor – and your phone will tell you which one. Fix: open Settings > Battery (iPhone or Android), find the app with unusually high background activity, then force-close, update or reinstall it. This often pairs with rapid battery drain, covered in why your iPhone battery drains so fast.

A software bug after an update

After a major update, phones re-index photos and finish housekeeping, which can run warm for a day or two. Fix: give it 24–48 hours; if it is still hot, restart, install any pending updates (the bug may already be patched), and as a last resort reset settings – not a full erase.

Poor signal

In a weak-signal area the phone boosts its radio power to stay connected, and constant searching generates heat. Fix: turn on Wi-Fi calling, and use Airplane mode in known dead zones (a basement, a lift, deep countryside) so it stops hunting for a tower.

A thick case trapping heat

Rugged, insulating cases are great for drops but poor for cooling – they wrap the heat-shedding frame in a blanket. Fix: take the case off while gaming or charging, and whenever the phone runs hot to help it cool faster.

Wireless charging heat

Wireless charging is less efficient than a cable, and the lost energy comes out as heat. Fix: use a cable for quick top-ups, keep the pad ventilated, and take the case off if it struggles through it.

When the cause is hardware

If you have ruled out the everyday causes and the phone still runs hot – particularly when idle – the problem is more likely inside. A swollen battery is also a hardware cause, but it is a safety issue covered in its own section below.

An ageing battery

Lithium-ion batteries wear out over hundreds of charge cycles. As a cell ages its internal resistance rises, so it runs warmer under load and holds less charge. A phone two or three years old that warms easily and drops charge quickly is often simply due for a new battery. On iPhone, check Settings > Battery > Battery Health & Charging; a low Maximum Capacity confirms it. Our guide on what battery percentage is too low explains the sensible replacement threshold.

A failed battery

A battery can also fail more abruptly: shutdowns even at 30–40% charge, refusing to hold charge, and running hot. In that state it should be replaced rather than nursed along.

A board or charging-circuit fault

A failing power-management chip, charging IC or a short on the logic board can generate heat – often around the charging port – even when idle. If it is hot in one spot, charges poorly, and the everyday fixes change nothing, it points to a board-level fault needing proper diagnosis.

Liquid damage

Water and corrosion cause shorts, and shorts cause heat. If the phone got wet – recently or weeks ago – and has started running hot, corrosion may be spreading inside, and needs professional cleaning promptly before it worsens.

Safety: a swollen or very hot battery

Stop and read this. A swollen battery is a safety hazard. If your phone's screen or back glass is lifting, there is a new gap around the edges, the phone rocks when laid flat, or the battery feels dangerously hot, treat it as urgent.

A swelling cell is venting gas, and a punctured or crushed lithium-ion battery can catch fire. To stay safe:

• Stop using and stop charging it immediately. Unplug it.
• Power it down if you can do so safely.
• Do not press, bend or puncture the phone, and never try to prise out a swollen battery yourself.
• Keep it away from heat, sun and anything flammable, on a hard, non-flammable surface.
• Do not put it in the freezer or fridge – rapid cooling causes internal condensation and does not make the cell safe.
• Get it to a professional for a battery replacement as soon as possible, and never bin a swollen battery in normal waste.

Swelling never repairs itself and only worsens. The fix is a fresh, correctly fitted battery, after which the phone is safe to use again.

How to cool a hot phone down safely

If your phone is hot right now from everyday use, cool it down safely:

• Close heavy apps and games, and take the case off so the frame can shed heat.
• Move it out of the sun into a cool, shaded spot – not the fridge or freezer, which causes condensation and thermal shock.
• Unplug it if charging, and switch on Airplane mode or power it off for a few minutes – never leave it cooling under a duvet or pillow.

Everyday overheating should ease within minutes. If it does not, or returns the moment you pick the phone up, the cause is likely inside.

When it needs a professional repair

Book a repair, rather than keep troubleshooting, if any of the following apply:

• The phone is hot when idle or under light use, with no heavy app to blame
• Battery Health has dropped well down and heat comes with fast battery drain
• There is any sign of swelling – a lifting screen, a gap, or the phone rocking when flat
• It started running hot after the phone got wet
• The heat is localised at the charging port and charging has become unreliable
• Overheating persists after you have updated software, removed the case and ruled out a rogue app

In most cases the fix is a battery replacement; in a minority it is a board-level or liquid-damage repair, which is why a proper diagnosis matters. At celltech, iPhone battery replacement starts at £44.95 for models such as the iPhone 11, 12 and 13, with the iPhone 16 at £54.95, the iPhone 14 at £69.95 and the iPhone 15 at £74.95 – see the full breakdown in our iPhone battery replacement cost guide. Standard repairs include free diagnostics, and we publish our prices openly rather than hiding them behind a quote wall.

celltech is a UK-wide, mail-in repair specialist covering roughly 2,467 device models, rated 4.8 stars. Posting your phone in is tracked and insured both ways, and it comes back fixed. Every standard repair, including battery replacement, carries our 27-month guarantee – more than double the 12 months most independent UK repairers offer, and far longer than a manufacturer's typical 90-day repair warranty.

Preventing overheating

A few habits keep a phone cool and extend the life of its battery:

• Keep software up to date – updates often fix the bugs that cause runaway heat
• Never leave the phone in a hot car, on a dashboard or in direct sun
• Avoid gaming or streaming while fast-charging, and charge on a hard, cool surface
• Use a good-quality charger and cable; cheap, uncertified chargers can overheat
• Take a heavy, insulating case off when gaming or charging
• Replace an ageing battery before it becomes a heat – or safety – problem

Frequently Asked Questions

Why does my phone get hot when I am not even using it?

Heat while idle is the clearest sign something is off. Common causes are a background app pegging the processor (check Battery usage), the phone left in the sun or a warm pocket, a stuck process after an update, or a hardware fault such as an ageing battery. If everyday fixes do not help, have the battery checked.

Is it normal for my phone to get hot while charging?

Mild warmth is normal, a little more during fast or wireless charging. It becomes a problem if the phone is too hot to hold, you are using it heavily, or it is in a thick case on a soft surface. Take the case off, charge on a hard cool surface, and avoid gaming while plugged in. Persistent serious heat can mean a worn battery or charging-circuit fault.

Can an overheating phone catch fire or explode?

Everyday warmth from heavy use will not. The real risk is a damaged or swollen lithium-ion battery, which can catch fire if punctured, crushed or severely overheated. That is why a swollen battery should be taken out of use straight away and replaced by a professional. Treated sensibly, the risk is very low.

Should I put my hot phone in the fridge or freezer?

No. Rapid cooling causes condensation inside the phone, which can corrode the electronics, and the temperature swing can damage the screen and battery. Cool it the safe way: remove the case, move it into shade, switch it off or into Airplane mode, and let it return to room temperature on its own.

Will a new battery fix my overheating phone?

If the heat is caused by an ageing, failed or swollen battery – the most common hardware cause – then yes, a fresh battery resolves both the heat and the poor battery life. If the cause is a board or liquid-damage fault, a battery alone will not fix it, which is why we diagnose first. Check prices for your model in our iPhone battery replacement cost guide.

How does celltech's mail-in repair work for an overheating battery?

You book online and post your phone to us with tracked, insured delivery covered both ways. We diagnose the cause – standard repairs include free diagnostics – carry out the repair, test it, and post it back fixed, with battery replacements covered by our 27-month guarantee. If you suspect a swollen battery, stop using the phone and get it to us promptly rather than continuing to charge it.