Your phone usually gets at least a bit warm while charging, but noticeable or uncomfortable heat is a sign something’s off. Here’s a quick, clear breakdown in the style you asked for.

Why does my phone get hot when charging?

Quick Scoop

When your phone charges, electrical energy turns into chemical energy in the battery, and some of that turns into heat. A little warmth is normal, but strong or sudden heat often comes from fast charging, using the phone heavily while plugged in, poor ventilation (like charging under a pillow), or low‑quality/damaged chargers and cables.

The main reasons (in plain language)

1. Fast charging = more power, more heat

Modern “fast charge” or “quick charge” bricks push higher voltage/current into the battery so it fills up faster. More power flowing in a short time means more resistance inside the battery and electronics, which naturally produces extra heat.

Signs this might be your case:

  • You’re using a 20W/30W+ or other “fast” adapter.
  • It gets hottest from 0–60% and then cools a bit afterwards.

2. Using the phone while it charges

If you’re gaming, watching videos, doing video calls, or using GPS/maps while charging, the processor and graphics chip are working hard at the same time the battery is filling. That stacks two heat sources together, so the phone can feel very hot, especially around the back/near the camera or processor area.

Typical “this is the cause” clues:

  • Heat spikes during games, streaming, or video calls, then drops when you stop.
  • Battery drains slowly or barely goes up while plugged in because usage is so heavy.

3. Poor ventilation or hot environment

Phones need airflow to dump heat. If you charge:

  • Under a pillow or blanket.
  • On a sofa, in a car in the sun, or in direct sunlight.
  • In a tight pocket or bag while on a power bank.

…then the heat just stays trapped around the phone. Even normal charging can become “overheating” if there’s nowhere for that heat to go.

4. Low‑quality, old, or damaged chargers and cables

Cheap or worn‑out adapters and cables may not regulate power smoothly. Instead of delivering steady current, they can:

  • Send power in little spikes.
  • Lose power as heat in the cable itself.
  • Cause the phone’s power management to work harder correcting fluctuations.

That wasted energy shows up as heat in both the phone and the charger.

Watch out for:

  • Knock‑off or super‑cheap chargers.
  • Frayed, bent, or loose cables.
  • Charger or cable itself getting very hot to the touch.

5. Overcharging or staying at 100% for hours

Some phones manage this well, but on others, sitting at 100% and staying plugged in (like overnight) can keep tiny amounts of current flowing in and out to maintain “full.” That trickle can keep the phone warm for longer, especially on older devices or with low‑quality adapters.

Modern phones are better at stopping true overcharge, but “battery maintenance” at the top end can still generate mild heat.

6. Background apps, software bugs, or misbehaving apps

Sometimes the heat isn’t mainly from charging, but from the phone acting like it’s under full load all the time:

  • A buggy app stuck running in the background.
  • Heavy social media, navigation, or messaging apps constantly using CPU, data, GPS.
  • System or OS bugs causing high CPU usage.

Your phone then runs hot even when the screen is off, and charging on top of this background load pushes the temperature higher.

7. Battery age or damage

As lithium‑ion batteries age, their internal resistance goes up. That means more of the incoming charge is lost as heat instead of stored as usable energy. A worn or damaged battery is more likely to:

  • Get hot from normal charging.
  • Drop charge fast, even after reaching 100%.
  • Show warnings or unexpected shutdowns.

In rare cases, a swollen or physically damaged battery can be dangerous and should be checked immediately.

8. Wireless charging inefficiency

If you use wireless charging (especially wireless fast charging), energy has to pass through coils and some is lost as heat. Misalignment of phone and pad or cheap wireless chargers can increase losses, leading to a hot back panel and a warm charging pad.

When should you worry?

Normal, expected heat:

  • Slight warmth near the back or bottom of the phone.
  • Warmer during the first 30–40 minutes of fast charging, then cooling down.
  • Mildly warm while streaming or gaming and charging at the same time.

Concerning signs (time to take action):

  • The phone is almost too hot to hold comfortably.
  • It stops charging, shows an “overheating” or “temperature” warning, or the screen dims badly.
  • It smells like burning, you see discoloration, or the battery looks swollen.
  • Heat appears suddenly after a new charger, cable, or app.

What you can do to cool it down (and protect it)

Simple habits that help a lot

  1. Use good‑quality, certified chargers and cables
    • Prefer the brand’s own charger or trusted certified ones.
    • Replace frayed/bent cables and any adapter that gets very hot.
  1. Avoid heavy use while charging
    • Pause gaming, video calls, or 4K video recording while plugged in.
    • If you must use it, lower brightness and close unnecessary apps.
  1. Give it room to breathe
    • Don’t charge under a pillow, blanket, or in direct sun.
    • Take thick or rubbery cases off if they trap heat.
  1. Tweak charging style
    • You can turn off “fast charge” in some phones, or use a lower‑wattage charger for overnight charging.
    • Unplug once you’re near 80–90% if you want to be extra nice to the battery.
  1. Check apps and software
    • Update your phone’s OS and apps.
    • Look in battery or analytics settings for apps using unusual power and uninstall/limit them.
  1. If the battery seems old or damaged
    • If your phone is several years old and gets hot even on slow charge, have the battery checked or replaced by a professional.
    • Stop using it immediately if you see swelling, popping, or smell burning.

Mini “is this normal?” table

[3][7][5] [9][3][5] [6][7][5] [8][5] [9][5][8]
Situation Heat level Usually OK?
Fast charging from 10% to 60%, phone slightly warm Light to medium warmth Generally normal if no warning messages.
Gaming + charging on a bed with no airflow Medium to high heat Common but not ideal; improve ventilation and reduce usage.
Phone and charger both very hot, new cheap adapter High heat, uncomfortable to touch Not normal; stop using that charger and replace with a certified one.
Old phone, heats on any charger and battery drains fast Medium heat, frequent Likely battery wear; consider a battery replacement.
Overheating warning on screen while charging in hot car Very high heat, system throttling Serious; cool the phone down and avoid charging in high heat.
**Bottom note:** Information gathered from public forums or data available on the internet and portrayed here.