Where to find battery health on your iPhone

Your iPhone stores a battery health report in Settings, and you can read it in under a minute. Open Settings, tap Battery, then tap Battery Health & Charging. The screen shows your battery's maximum capacity as a percentage — this is the number that matters most.

Maximum capacity tells you how much charge your battery can hold now compared to when it was new. A new iPhone battery is at 100%. After a year or two of normal use, it typically drops to 80–90%. After three or four years, 70–80% is common. The lower the percentage, the faster your phone drains during the day.

The same screen also shows Charging Optimization status. This feature learns your charging habits and slows down charging speed overnight to reduce wear. It is on by default and you can turn it off if you prefer, but leaving it on extends battery life over time.

Key Takeaways

  • Maximum capacity percentage in Settings > Battery > Battery Health & Charging shows how much charge your battery holds compared to when it was new.
  • Batteries naturally drop from 100% to 80–90% in the first year and continue declining with age and use.
  • Below 80% capacity, you will notice faster drain during the day, and Apple considers the battery degraded enough to replace under warranty.
  • Charging Optimization is on by default and slows overnight charging to reduce wear; turning it off speeds up charging but ages the battery faster.
  • You cannot improve maximum capacity once it drops — only replace the battery.

What maximum capacity percentage really means

Maximum capacity is not the same as your current charge level. If your battery is at 80% maximum capacity and you charge it to 100%, you are getting 80% of a full new battery's charge, not 80% of your current battery's full charge. The percentage tells you the total amount of energy your battery can store.

A battery at 50% maximum capacity will drain twice as fast as a new one, even if you use your phone the same way. You might go from a full day of use to needing a charge by mid-afternoon. This is why the number matters — it predicts how long your phone will last between charges.

When Apple considers a battery worn out

Apple's warranty covers battery replacement if maximum capacity drops below 80% within one year of purchase. After one year, the battery is considered a consumable part, and replacement costs money — typically $69 to $99 depending on your iPhone model.

You do not have to wait for Apple's threshold. If your battery is at 85% and drains too fast for your needs, you can replace it anytime. Some people replace at 80%, others wait until 60% or lower. The choice depends on how much the drain bothers you and whether you can afford the service fee.

How to slow battery degradation

Battery health declines with age and heat, and you cannot stop it completely. But you can slow it down. Keep your phone out of direct sunlight and away from hot cars. Avoid letting the battery drain to 0% regularly — charging when you hit 20% is gentler than waiting until the phone shuts down. Charging overnight with Charging Optimization on is safer than fast-charging during the day.

Using your phone while it charges generates heat, which ages the battery faster. If you use your phone heavily while plugged in, the battery will degrade sooner than if you charge it while the phone is idle. This is why Charging Optimization slows the charge at night — your phone is not in use, so slower charging does not affect you but does protect the battery.

Other battery information on the health screen

Below maximum capacity, you may see a section called Peak Performance Capability. If it says "Your battery is currently supporting normal peak performance," your phone is running at full speed. If it says your battery cannot support peak performance and your phone may unexpectedly shut down under heavy load, your battery is severely degraded.

This message appears when maximum capacity drops very low — usually below 20%. It means your battery cannot deliver the power your phone needs during demanding tasks like gaming or video recording. The phone will slow itself down to prevent shutdowns. Replacing the battery restores full performance.

Checking battery health on older iOS versions

If you are running iOS 16 or earlier, the battery health screen looks slightly different but shows the same information. Open Settings, tap Battery, then tap Battery Health. You will see maximum capacity and a note about peak performance. The steps are the same; only the menu name changed in iOS 17.

If you cannot find Battery Health in Settings, make sure your iPhone is updated to the latest iOS version available for your model. Older phones running very old iOS versions may not have this feature at all — in that case, you can take your phone to an Apple Store and ask them to check the battery health for you.

What to do if your battery health is low

If maximum capacity is below 80% and your phone drains too fast, you have two choices: replace the battery or replace the phone. Battery replacement costs $69–$99 and takes one to two hours at an Apple Store, or longer if you mail it in. A new battery restores your phone to nearly full performance.

If your phone is old and has other problems — cracked screen, slow processor, outdated software — replacing the battery may not be worth it. But if the phone otherwise works well, a new battery can extend its life by two or three years. Check your maximum capacity, decide whether the drain affects your daily use, and choose accordingly.

Frequently Asked Questions

Can I improve my battery health percentage?

No. Once maximum capacity drops, only replacing the battery restores it. Charging habits and temperature management slow the decline but cannot reverse it. The percentage only goes down with time and use.

Is 80% battery health bad?

Not when ready. Most people do not notice a difference at 80%. You will start to see faster drain somewhere between 70% and 60%, depending on how much you use your phone. At 50% or lower, the drain becomes obvious — you may need to charge twice a day.

Why did my battery health drop so fast?

Heat is the main culprit. If you use your phone in a hot car, charge it in direct sunlight, or use it heavily while charging, the battery ages faster. Letting it drain to 0% regularly also speeds degradation. Normal use in cool conditions slows the decline.

Should I turn off Charging Optimization?

No, unless you need your phone fully charged at a specific time each morning. Charging Optimization slows overnight charging to reduce wear, and you will not notice the difference. Turning it off charges faster but ages the battery sooner.

Does battery health affect my warranty?

Apple covers battery replacement if capacity drops below 80% within one year of purchase. After one year, the battery is not covered by the standard warranty, but you can pay for replacement. AppleCare+ covers battery replacement for the full plan period.