Why is my phone overheating? Causes, fixes and when to worry

Almost every phone gets warm. A modern smartphone packs a powerful processor, a lithium-ion battery and several radios into a sealed glass-and-metal slab with no fan, so the only way to get rid of heat is through its body. That's why the back or frame warms up when you push it.

The question is whether your phone is warm or overheating. This guide explains the difference, the usual causes, and what you can do about it.

Warm vs overheating: how to tell

Normal warmth: the phone feels warm, sometimes quite warm, during fast charging, a long gaming session, satellite navigation, a video call or recording 4K video. It cools down within minutes once you stop.

Overheating is when one or more of these happens:

• the phone is uncomfortable to hold;
• you see a temperature warning, or the phone refuses to charge, turns off the flash or dims the screen;
• performance drops sharply: games stutter, the camera closes, apps lag;
• it gets hot while idle in your pocket or on a table.

Phones protect themselves. When they get too hot, the system lowers processor speed (this is called thermal throttling), dims the display, pauses charging and, as a last resort, shuts down. Apple, for example, lists an operating ambient temperature of 0–35 °C for iPhone; other makers publish similar ranges.

The most common causes

1. Charging, especially fast or wireless

Charging a battery always produces heat, and fast charging produces more. Wireless charging is less efficient than a cable, so more energy turns into heat, and a misaligned phone on a pad gets warmer still. Using the phone heavily while it charges stacks two heat sources on top of each other.

2. Demanding apps and games

3D games, video editing, long camera sessions and on-device AI features keep the processor and graphics at high load. Even flagship chips throttle under sustained load; short benchmarks don't show it. That's why reports such as the recent Snapdragon overheating claims focus on long, heavy workloads.

3. Weak signal and 5G

When reception is poor, the modem boosts its transmit power and keeps searching for a better tower. Basements, trains and rural areas can make a phone warm even when you aren't touching it. Using mobile hotspot adds even more load.

4. Heat and sunlight

A phone on a car dashboard, a beach towel or a sunny café table can heat up quickly even with the screen off. Add navigation and charging in a hot car and throttling is almost guaranteed.

5. Thick cases

A case doesn't make heat, but a thick rugged or leather case traps it, especially during charging.

6. Software problems

A buggy update, a misbehaving app stuck in the background, or (less often) malware can keep the processor busy all the time. The tell-tale sign is heat plus fast battery drain while you aren't using the phone. Malicious clones of popular apps do this; see how to spot fake apps on Google Play.

7. An ageing or damaged battery

Older batteries have higher internal resistance and get warmer when charging. A damaged or swollen battery is a safety issue, covered below.

10 fixes that actually help

1. Stop and let it cool. Close the game or camera, lock the screen and put the phone on a hard surface in the shade.
2. Take the case off while charging or gaming.
3. Don't use heavy apps while charging. If you need to, use a slower charger or cable.
4. Use a decent charger and cable. A certified USB PD charger negotiates the right power; a cheap no-name adapter may not. Our USB-C charger guide explains what to look for.
5. Align wireless chargers properly, or switch to a cable on hot days.
6. Never cool it in the fridge or freezer. Rapid temperature changes can cause condensation inside the phone. Just let it cool at room temperature.
7. Check battery usage in Settings. An app using lots of battery in the background is often the source of heat; update, restrict or uninstall it.
8. Install system and app updates. Makers regularly fix thermal and battery bugs.
9. Lower the load: reduce screen brightness, cap game frame rates, and switch off 5G or hotspot when signal is poor.
10. Restart the phone. It clears stuck processes, and it's quick.

On the go, the same rules apply to power banks: they warm up too, so don't stack the phone and battery in a hot pocket. See our power bank buying guide.

Does heat damage the phone?

Short bursts of heat are normal and the protections exist for that reason. Long-term, though, heat ages lithium-ion batteries faster. A phone that regularly sits hot while charging overnight under a pillow or in direct sun will lose battery capacity sooner. Many phones now offer optimised or limited charging (for example, stopping at 80%) that reduces time spent at full charge and heat stress; it's worth turning on.