Where to find your iPhone battery health

Your iPhone stores a battery health report that you can read in Settings. Open Settings, tap Battery, then tap Battery Health & Charging. You will see a percentage labeled "Maximum Capacity" — this is your battery's current health.

Maximum Capacity tells you how much charge your battery can hold compared to when it was new. A new iPhone battery is at 100%. After normal use over months or years, this number drops. If your battery shows 80%, it can hold 80% of the charge it held on day one.

Below Maximum Capacity, you may also see "Peak Performance Capability." This line appears only if your battery has degraded enough that iOS has started managing your phone's speed to prevent unexpected shutdowns. If you see text here, your battery needs attention sooner rather than later.

Key Takeaways

  • Maximum Capacity in Settings > Battery > Battery Health & Charging shows what percentage of your battery's original charge it can still hold.
  • A battery at 80% or above is considered healthy; below 80% means the battery is aging and may need replacement within months.
  • Peak Performance Capability text means iOS is already slowing your phone to protect the battery, and replacement is recommended soon.
  • Battery health degrades from normal use, heat exposure, and charging habits — not from checking the health report itself.
  • Replacing an iPhone battery through Apple costs less than buying a new phone and restores performance if your device is slowing down.

What different battery health percentages mean

A battery at 100% is brand new or has been replaced recently. Most iPhones stay at 100% for the first few weeks of use, then begin a slow decline. This is normal and expected.

Between 100% and 80% is the normal aging zone. Your battery is working as designed. You may notice the phone needs charging more often than it did when new, but performance stays the same. Most people replace their iPhone before the battery drops below 80%, so you may never see lower numbers.

At 80% or below, your battery is considered degraded. iOS may start managing performance to prevent sudden shutdowns — this is the Peak Performance Capability message. Your phone may feel slower, especially when running multiple apps or using the camera. Battery replacement becomes a practical choice rather than an optional upgrade.

Below 50% means the battery is significantly worn. Your phone will drain quickly, shut down unexpectedly even with charge remaining, and feel noticeably slow. Replacement is urgent at this point.

Why battery health drops over time

Every time you charge your iPhone, the battery goes through a charge cycle. A cycle is a full drain from 100% to 0%, or the equivalent spread across multiple days. Apple designs iPhone batteries to retain 80% of their capacity after 500 charge cycles — roughly one to two years of typical use.

Heat is the biggest factor that speeds up battery aging. Leaving your phone in a hot car, using it while charging, or running demanding apps in warm weather all generate heat that degrades the battery faster. Cold temperatures slow the battery down temporarily but do not permanently damage it the way heat does.

Charging habits matter too. Letting your battery drain completely before charging, or leaving it plugged in overnight every night, both accelerate aging. Keeping your battery between 20% and 80% charge extends its life, though this is not practical for daily use. The good news is that normal charging — plugging in when you need to — is fine. You do not need to obsess over charging patterns.

When to replace your iPhone battery

If your battery is at 80% or above and your phone runs normally, there is no urgent reason to replace it. Keep using it. The battery will continue to age, but slowly.

If your battery is below 80% and your phone is slowing down, or if you see Peak Performance Capability text in Settings, replacement will restore your phone's speed. You do not need to buy a new iPhone — a battery replacement is much cheaper and fixes the problem.

If your phone shuts down unexpectedly even when the battery percentage shows charge remaining, the battery is failing and needs replacement when ready. This usually happens below 50% health.

Apple replaces iPhone batteries at Apple Stores and Apple Authorized Service Providers. The cost varies by iPhone model but is typically between $50 and $100. The process takes a few hours to a few days depending on whether parts are in stock. Some third-party repair shops also replace batteries, often for less money, though Apple's warranty covers their replacements.

How to slow down battery aging

Keep your phone cool. Avoid leaving it in direct sunlight, in a hot car, or in a pocket against your body during heavy use. If your phone gets hot while charging, unplug it and let it cool down. Using a case that insulates heat can actually speed up aging, so consider removing the case during long charging sessions.

Enable Optimized Battery Charging in Settings > Battery > Battery Health & Charging. This feature learns your charging patterns and slows down charging to 80% until you need the phone, then finishes the last 20% closer to when you wake up. This reduces the time your battery spends at 100%, which is when it ages fastest.

Use Low Power Mode when your battery is below 20%. This reduces background activity and dims the screen slightly, which cuts power draw and gives you more time before the next charge. You can also enable Low Power Mode automatically at a certain battery percentage in Settings > Battery.

Avoid leaving your phone plugged in overnight if you can. If you must charge overnight, Optimized Battery Charging helps by pausing the charge at 80% until morning. If your phone is older and does not have this feature, unplugging after a few hours is better than leaving it plugged in all night.

Reading your battery health report accurately

The Maximum Capacity number is the only battery health metric that matters for most users. Ignore everything else on that screen unless you are troubleshooting a specific problem.

The Peak Performance Capability section will show one of three states: your phone is operating at peak performance (no text shown), your battery is degraded and iOS is managing performance, or your battery is so worn that iOS cannot manage performance anymore and you may see unexpected shutdowns. If you see any text in this section, your battery needs attention.

Do not confuse battery health with battery percentage. Battery percentage (the number in the top right of your screen) is how much charge is in the battery right now. Battery health is how much charge the battery can hold total. A phone at 50% charge with 80% health is fine. A phone at 100% charge with 20% health will drain very quickly.

Frequently Asked Questions

Does checking my battery health damage the battery?

No. Looking at your battery health in Settings does not affect the battery at all. The report is just information iOS has already collected. Checking it as often as you want will not speed up aging or cause any harm.

Why did my battery health drop 10% in one month?

Rapid drops usually mean heat exposure or heavy use. Check whether you have been charging while using the phone, leaving it in a warm place, or running demanding apps like games or video recording. If the drop continues, your phone may have a hardware problem and should be checked by Apple.

Can I replace just the battery instead of buying a new iPhone?

Yes. Apple and most authorized repair shops replace batteries for $50 to $100 depending on your model. This is much cheaper than a new phone and restores performance if your device is slowing down due to battery age.

What is a charge cycle and how do I count them?

A charge cycle is one full drain and recharge, or the equivalent spread across multiple days. If you use 50% of your battery one day and 50% the next, that is one cycle total. You do not need to count cycles yourself — iOS tracks them and uses that data to calculate your Maximum Capacity percentage.

Is it bad to leave my iPhone charging overnight?

Overnight charging accelerates battery aging slightly because the battery spends hours at 100% charge, which is when it ages fastest. Enabling Optimized Battery Charging solves this by pausing the charge at 80% until morning. If your phone is older and lacks this feature, unplugging after a few hours is better than leaving it plugged in all night, but the difference is small.