A new iPhone battery lasts two to three years under normal use

An iPhone battery degrades over time, and how fast depends on how you use it. Apple designs its batteries to retain 80 percent of their original capacity after 500 full charge cycles—that is, 500 times charging from empty to full. For most people, that works out to roughly two to three years before the battery noticeably loses power and stops lasting a full day.

One charge cycle does not mean one day. If you charge your phone to 50 percent, use it, then charge it to 100 percent, that counts as half a cycle. So if you top up your phone multiple times a day without fully draining it, you are spreading those 500 cycles across a longer calendar period.

The timeline also depends on your habits. If you keep your phone plugged in constantly, run heavy apps all day, or expose it to heat, the battery wears faster. If you charge it overnight and use it lightly, it lasts longer.

Key Takeaways

  • Apple batteries are designed to hold 80 percent capacity after 500 full charge cycles, which typically takes two to three years.
  • One charge cycle is a full drain and recharge, not a single day—topping up your phone multiple times counts as partial cycles.
  • Heat, constant charging, and heavy app use wear batteries faster than light use and moderate temperatures.
  • You can check your battery's current health in Settings > Battery > Battery Health & Charging to see how much capacity remains.
  • When capacity drops below 80 percent, the phone may slow down or shut off unexpectedly, but the battery can still function for months or years.

How to check your iPhone battery's current health

Open Settings, tap Battery, then tap Battery Health & Charging. You will see Maximum Capacity as a percentage—this tells you how much charge your battery can hold compared to when it was new. If it shows 85 percent, your battery holds 85 percent of its original power.

Below that, you may see a message about Peak Performance Capability. If your battery capacity has dropped significantly, iOS may throttle your phone's processor to prevent unexpected shutdowns. This is why an older iPhone sometimes feels slow—it is not always a software update problem.

What happens when battery capacity drops below 80 percent

The phone does not stop working. Instead, you will notice it drains faster and may not last a full day on a single charge. Some users see unexpected shutdowns when the battery is under heavy load, even if the percentage indicator shows 20 or 30 percent remaining.

iOS may also set up throttling, which slows your processor to reduce power draw. You can turn this off in Battery Health & Charging, but doing so increases the risk of sudden shutdowns. Most people leave it on and straightforward charge more often.

Factors that wear out iPhone batteries faster

Heat is the biggest culprit. Leaving your phone in a hot car, using it while charging, or running demanding apps in warm weather all speed up degradation. Lithium batteries lose capacity permanently when exposed to high temperatures, and the damage is irreversible.

Constant charging also matters. Keeping your phone plugged in overnight or all day, even at 100 percent, stresses the battery. Modern iPhones have optimized charging that slows charging after 80 percent, but leaving it plugged in for hours still causes wear.

Deep discharges—letting the battery drain completely—are harder on lithium batteries than partial cycles. Charging from 20 to 80 percent is gentler than cycling from 0 to 100 percent repeatedly.

Heavy use like gaming, video recording, or navigation drains the battery faster and generates heat, compounding the wear.

How long a battery lasts if you extend its lifespan

If you manage heat and charging carefully, you can stretch a battery to four or even five years. Keep your phone cool, avoid leaving it plugged in constantly, and try not to let it fully drain. Charge it to 80 percent when possible and unplug it.

Some users enable Low Power Mode during the day to reduce drain, then charge overnight. Others use a case that dissipates heat or avoid using the phone while it charges. These habits do not double the battery life, but they can add a year or more to the timeline.

When to replace your iPhone battery

You have two options: replace the battery or replace the phone. Apple offers battery replacement at an Apple Store or authorized service provider. The cost varies by model but typically ranges from $50 to $100. The process takes a few hours to a few days depending on availability.

If your phone is older than four or five years, or if the battery capacity has dropped below 50 percent, you may want to weigh the cost of a new battery against the cost of a new phone. A battery replacement can extend the phone's useful life by another two to three years.

Third-party repair shops also offer battery replacement, often for less money, but Apple's warranty does not cover damage from non-Apple repairs. If you go that route, choose a reputable shop and ask whether they use genuine or aftermarket batteries.

Signs your battery needs replacement soon

The phone shuts down unexpectedly even when the battery shows 20 or 30 percent. This happens because the battery cannot deliver the power the phone demands, even though it still holds charge. It is a sign the battery is near the end of its useful life.

The phone drains visibly while you watch—you see the percentage drop in real time during normal use. This is different from normal drain and suggests the battery is failing.

The phone feels warm during light use or charging. Excess heat during normal operation can mean the battery is degrading and working harder to deliver power.

Frequently Asked Questions

Can I replace my iPhone battery myself?

Technically yes, but it is not recommended. iPhones are sealed devices, and opening one requires special tools and skill. You risk damaging the screen, logic board, or other components. Apple and authorized repair shops have the right equipment and can may provide the work. If you want to try it, watch a full teardown video first and understand you may break the phone.

Does leaving my iPhone plugged in overnight ruin the battery?

Not when ready, but it does cause wear over time. Modern iPhones slow charging after 80 percent and use optimized charging to reduce stress, but the battery still degrades faster if left plugged in for hours every night. Unplugging it when full is gentler, but occasional overnight charging will not destroy the battery in a month or two.

Why does my iPhone slow down as the battery gets older?

iOS throttles the processor when battery capacity drops significantly to prevent unexpected shutdowns. A degraded battery cannot deliver power as quickly, so the phone slows down to match what the battery can supply. You can disable this in Battery Health & Charging, but it increases shutdown risk.

Is it worth replacing the battery or should I buy a new phone?

If your phone is two to three years old and the battery capacity is below 80 percent, replacement usually costs less than a new phone and extends the device's life another two to three years. If the phone is five years old or older, or if other hardware is failing, a new phone may be the better choice. Compare the battery replacement cost to the price of a new device for your model.

Does using Low Power Mode damage the battery?

No. Low Power Mode reduces processor speed and background activity to cut power draw, which actually reduces battery wear over time. It does not harm the battery itself. Using it regularly can help extend the overall lifespan.