What to expect from an iPhone battery's lifespan

Apple designs iPhone batteries to retain 80 percent of their original capacity after 500 full charge cycles. A charge cycle means draining the battery from 100 percent to zero and charging it back to 100 percent — not necessarily in one day. Most people hit 500 cycles in roughly two to three years of normal use.

After that point, the battery still works, but it holds less charge. An iPhone that lasted a full day on a single charge when new might last 16 to 18 hours at 80 percent capacity. The phone itself remains functional; only the battery degrades.

If you use your iPhone heavily — charging it multiple times per day — you will reach 500 cycles faster, sometimes in 18 months. Light users who charge once every two days might not hit 500 cycles for four years. The timeline depends entirely on your charging habits, not on calendar time.

Key Takeaways

  • iPhone batteries are designed to retain 80 percent capacity after 500 charge cycles, which typically takes two to three years for average users.
  • A charge cycle is a full drain from 100 to zero and back to 100, not a daily charge — heavy users complete cycles faster than light users.
  • Battery degradation is gradual; at 80 percent capacity your iPhone still works normally but holds noticeably less charge per day.
  • You can check your battery's current health percentage in Settings > Battery > Battery Health & Charging on any iPhone running iOS 16 or later.
  • Replacement batteries from Apple cost between $69 and $99 depending on your model, and most replacements take one to two hours at an Apple Store.

How to check your battery's current health

Open Settings, tap Battery, then tap Battery Health & Charging. You will see a percentage labeled "Maximum Capacity" — this is your battery's current health relative to when it was new. If it shows 85 percent, your battery holds 85 percent of the charge it held on day one.

The same screen shows "Condition" at the bottom. If it says "Normal," your battery is performing as expected for its age. If it says "Service Recommended," the battery is degraded but still usable. If it says "Service Battery," Apple considers the battery worn enough that you should replace it soon, though the phone will continue to work.

This feature is available on iPhone XS and newer models running iOS 16 or later. Older iPhones do not display this information, but you can still take the phone to an Apple Store and ask a technician to check the battery health for you.

When battery replacement becomes necessary

You do not have to replace your battery at any specific percentage. The decision depends on whether the reduced capacity affects your daily use. If your iPhone still lasts a full day, there is no urgent reason to replace it. If you are charging it twice a day or more, or if it shuts down unexpectedly when the battery percentage is still above zero, replacement makes sense.

Unexpected shutdowns happen when the battery can no longer deliver the power the phone demands, even though charge remains. This is different from the battery straightforward being low. If your iPhone powers off at 20 percent battery, for example, the battery is likely too degraded to continue using safely.

Some people replace batteries at 80 percent capacity as preventive maintenance, especially if they plan to keep the phone for several more years. Others wait until the phone becomes inconvenient to use. Both approaches are reasonable — the battery will not suddenly fail, and degradation is gradual.

Factors that speed up battery degradation

Heat is the primary enemy of lithium-ion batteries. Leaving your iPhone in a hot car, using it while charging, or running demanding apps in direct sunlight all generate heat that ages the battery faster. Even brief exposure to high temperatures can cause permanent damage.

Charging habits matter less than most people think. Charging to 100 percent every day does not significantly shorten battery life compared to charging to 80 percent. However, letting the battery drop to zero regularly and then charging it back to 100 does complete a full cycle, which counts toward the 500-cycle limit.

Cold temperatures slow chemical reactions inside the battery and can make it seem like capacity has dropped, but this is temporary. Once the battery warms up, it performs normally again. Extreme cold (below freezing for extended periods) can cause permanent damage, but normal winter weather does not.

Battery replacement costs and timing

Apple charges $69 to $99 for an out-of-warranty battery replacement, depending on your iPhone model. Newer models like the iPhone 15 cost more than older models like the iPhone 11. If your iPhone is still under the one-year limited warranty and the battery health has dropped below 80 percent due to a manufacturing defect, Apple replaces it at no cost — though this is rare.

AppleCare+ covers battery replacement at no cost if the battery capacity drops below 80 percent while you have active coverage. If you do not have AppleCare+, you pay the full replacement fee.

Replacement usually takes one to two hours at an Apple Store if you have an appointment. Without an appointment, wait times vary by location but often run two to four hours. Some Apple Stores offer same-day service; others require you to leave the phone and pick it up later. You can also mail your iPhone to Apple for battery replacement, which takes five to seven business days plus shipping time.

Third-party battery replacement options

Independent repair shops and some electronics retailers offer iPhone battery replacement for $30 to $60, significantly less than Apple's price. The trade-off is that third-party batteries are often lower quality and may not last as long as Apple's original batteries.

If you choose a third-party replacement, verify that the shop uses batteries with genuine capacity ratings, not counterfeit or refurbished cells. Some shops will show you the battery's health report before and after replacement. Ask to see this documentation.

Third-party repairs do not void your warranty on the rest of the phone, but they may affect your ability to use certain features. Some iPhones display a warning that the battery is not genuine, and in rare cases, features like wireless charging or fast charging may not work correctly with a non-Apple battery.

Extending battery life between replacements

Enable Low Power Mode in Settings > Battery to reduce background activity and extend daily battery life. This does not slow down the phone noticeably but does reduce how much charge the battery uses each day, which means fewer charge cycles over time.

Keep your iPhone cool. Avoid leaving it in direct sunlight, in a car on a hot day, or in a pocket against your body for extended periods. If the phone gets warm during use, close apps and let it cool before continuing.

Charge your phone at moderate temperatures when possible. Charging in a cold room or a very hot room both stress the battery. Room temperature (around 70 degrees Fahrenheit) is ideal.

You do not need to let the battery drain to zero before charging, and you do not need to charge only to 80 percent. Normal charging patterns — plugging in when convenient and charging to 100 percent — are fine. The 500-cycle design limit accounts for typical use, not perfect use.

Frequently Asked Questions

Is it bad to leave my iPhone plugged in overnight?

No. Modern iPhones stop charging at 100 percent and do not draw power from the charger once full. Leaving the phone plugged in does not degrade the battery faster. However, if the phone is in a warm case or in a warm environment while plugged in, the heat can cause minor degradation over months. Unplugging after the phone reaches 100 percent is slightly better, but overnight charging is not harmful.

Why does my iPhone shut down at 20 percent battery?

The battery can no longer deliver the current the phone needs, even though charge remains. This happens when the battery is severely degraded. The phone shuts down to protect the battery from damage. This is a sign that replacement is overdue, not a software glitch.

Can I replace the battery myself?

iPhones are sealed devices, and opening one requires special tools and skill. Self-repair risks damaging the screen, logic board, or other components. Unless you have experience with phone repair, professional replacement is safer and often costs less than repairing accidental damage from a DIY attempt.

Does fast charging wear out the battery faster?

Fast charging generates more heat than standard charging, which does cause slightly faster degradation over time. The difference is small — a battery charged with fast charging might reach 80 percent capacity in 2.5 years instead of 3 years. If you charge slowly most of the time and use fast charging only when necessary, the impact is minimal.

What happens if I ignore a "Service Battery" warning?

The phone continues to work, but the battery will degrade further and unexpected shutdowns become more likely. You are not risking damage to the rest of the phone by waiting, but you are risking inconvenience. If you plan to keep the phone for another year or more, replacement is worth doing sooner rather than later.