Why Does My Phone Get Hot When Charging?

Some warmth during charging is normal — your phone is converting electrical energy into stored chemical energy, and that process always produces heat. The question is how warm, and why.

If your phone gets uncomfortable to hold, charges more slowly than usual, or flashes a temperature warning, something is pushing it past the normal range. Here’s what’s causing it and what to do.

Is It Normal for Your Phone to Get Hot When Charging?

Mild warmth is expected. Once temperatures climb past 40°C (104°F), the system starts throttling to protect itself — and sustained heat in that range causes real damage over time.

Temperature Range	How It Feels	What It Means
Below 35°C (95°F)	Slightly warm to the touch	Normal. No action needed.
35–40°C (95–104°F)	Warm, like a hot water bottle	Manageable. Monitor it.
40–45°C (104–113°F)	Uncomfortable to hold for long	Phone throttles charging speed to cool down.
Above 45°C (113°F)	Too hot to hold, almost burning	Risk of battery damage. Unplug immediately.

Why Does Your Phone Get Hot When Charging?

Charger and Cable Quality

A low-quality or uncertified charger sends unstable voltage to the battery circuit. Instead of clean, regulated power, the battery receives uneven current, which generates excess heat. Damaged cables cause the same problem: poor contact creates resistance, and resistance produces heat. Therefore, you should choose a certified charger or fast charging power bank for charging.

Using Your Phone While Charging

Running the screen, processor, and battery simultaneously generates heat from multiple sources at once. The charger is trying to fill the battery while the phone is actively draining it — the battery ends up working double-time. Wireless charging adds another layer: electromagnetic induction is inherently less efficient, with around 20–30% of the energy transfer lost as heat.

Ambient Temperature and Ventilation

Charging in direct sunlight, a hot car, or under a pillow traps heat with nowhere to go. Phones rely on passive cooling through the back panel — remove the airflow and temperatures climb regardless of charger quality. A thick rubber case has the same effect.

Fast Charging

Fast charging pushes higher voltage and current into the battery in a shorter window. More power means more heat — that’s physics, not a defect. It becomes a problem when combined with other heat sources like a hot room or a thick coat.

Aging Battery

As a battery ages, its internal resistance increases, meaning more energy is lost as heat rather than stored. If your phone is two or more years old and suddenly feels hotter during charging, battery degradation is likely the cause.

What Happens If Your Phone Keeps Overheating?

Battery capacity loss. Heat is the primary accelerant of lithium battery aging. Repeated high-temperature cycles cause the battery’s chemical structure to break down, permanently reducing how much charge it can hold.

Slower charging. Once the phone detects high temperatures, it throttles incoming power. The result is slower charging precisely when you want it fast.

Component degradation. Processors and power management chips are sensitive to sustained heat. Long-term overheating leads to performance drops, freezing, and unexpected shutdowns.

Battery swelling. A visible bulge in the casing means internal gas buildup from heat damage — a safety issue. Stop using the device immediately. The same heat-driven damage applies to charging accessories.

How to Cool Down an Overheating Phone Right Now

Unplug it. Stop pushing current into a hot battery — let it rest first.

Remove the case. A thick case traps heat against the back panel. Taking it off gives the phone direct airflow.

Move it somewhere cool. A hard, flat surface in an air-conditioned room is ideal. Avoid beds and couches that trap heat underneath.

Close all apps and switch to airplane mode. Background processes keep the processor active. Airplane mode cuts Wi-Fi, Bluetooth, and cellular simultaneously. 

How to Prevent It from Happening Again

Use certified chargers and cables. Uncertified adapters and cheap cables are the single most common cause of abnormal heat, and are not worth the risk. You can choose the Rorry portable charger, which has full certification and regulated PD output.

Don’t use your phone while charging. Especially for processor-heavy tasks like gaming or navigation. Let the battery focus on filling up.

Charge in a cool, ventilated space. Around 20–25°C (68–77°F) is optimal. Avoid direct sunlight, car dashboards, and soft surfaces that block airflow. If you prefer wireless, a quality wireless power bank on a hard surface in a cool room keeps temperatures well within the normal range.

Remove the case during charging. Thick or rubberized cases trap heat. It takes seconds and makes a measurable difference.

Stay in the 20–80% range when possible. Charging from near-empty to full puts the most stress on the battery. Topping up in the mid-range reduces both heat and long-term wear.

Monitor battery health. On iPhone: Settings > Battery > Battery Health. On Android: Settings > Battery. Below 80% health, heat during charging becomes harder to control — at that point, replacement may be the most effective fix.

Conclusion

A warm phone during charging is expected. An uncomfortably hot one points to a charger, a habit, or an environment, making the battery work harder than it should. Fix the input, fix the conditions, and most overheating problems resolve on their own. If heat persists, the battery itself may need replacing.

FAQs

1. Is it bad if my phone gets hot while charging? 

Mild warmth is normal. Sustained heat above 40°C (104°F) accelerates battery aging and can damage internal components. If it’s too hot to hold comfortably, unplug it.

2. Does fast charging make your phone hotter? 

Yes, by design. It becomes a problem when combined with other heat sources — a hot room, a thick case, or an active screen.

3. Why does my phone get hot but not charge? 

Usually a faulty cable, a dirty port, or an inconsistent charger. The phone receives enough current to generate heat, but not enough to register a proper charge. Try a different cable and clean the port.

4. Can overheating while charging damage my battery? 

Yes. Repeated high-temperature cycles permanently reduce how much charge the battery can hold.

5. Should I take my case off when charging? 

It helps, especially with thick or rubberized cases. If your phone regularly gets warm during charging, this is the simplest first step.