Where to find your battery health information

Your iPhone stores a battery health report that you can read in Settings without downloading anything or connecting to a computer. Open Settings, tap Battery, then Battery Health & Charging. You will see two numbers: Maximum Capacity and Peak Performance Capability.

Maximum Capacity tells you what percentage of the battery's original charge it can still hold. A new iPhone shows 100%. After a year or two of normal use, you might see 95% or 90%. Peak Performance Capability tells you whether the battery can still deliver the power your phone needs for demanding tasks, or whether iOS has slowed your processor to protect the battery.

These two numbers are the only official health information Apple provides on the device itself. You do not need to pay for a diagnostic or visit an Apple Store to see them — the information is built into every iPhone running iOS 16.1 or later.

Key Takeaways

  • Maximum Capacity appears in Settings > Battery > Battery Health & Charging and shows what percentage of original charge your battery can hold.
  • Peak Performance Capability tells you whether iOS has slowed your processor to protect a degraded battery, or whether your phone runs at full speed.
  • A battery below 80% Maximum Capacity may drain faster and need charging more often, but does not necessarily need replacement.
  • If Peak Performance Capability says "Not Supported" or mentions performance management, your battery is degraded enough that Apple recommends service.
  • Checking your battery takes 30 seconds and requires no tools, apps, or appointments.

What Maximum Capacity actually means for daily use

Maximum Capacity is a percentage of what your battery held when it was brand new. If it shows 85%, your battery can now hold 85% of the charge it held on day one. This does not mean your phone dies at 85% — it means the battery drains to empty faster than it used to.

A battery at 90% Maximum Capacity usually feels normal in daily use. You charge it at night and it lasts all day. At 80%, you might notice it drains noticeably faster, especially if you use your phone heavily. At 70% or below, you may need to charge twice a day or carry a charger with you.

The speed of decline depends on how you use your phone. Leaving it in a hot car, charging it constantly, or running demanding apps all day wears the battery faster. Using your phone at room temperature and letting the battery drop to 20% before charging slows degradation.

Understanding Peak Performance Capability messages

Peak Performance Capability has three possible states. "Your battery is in normal condition" means your battery can deliver full power and your phone runs at full speed. This is what you want to see.

"This iPhone has experienced an unexpected shutdown because the battery was unable to deliver the necessary peak power" means your battery degraded enough that iOS slowed your processor to prevent random shutdowns. Your phone will feel slower during heavy use — opening apps takes longer, games lag, video editing stutters. This slowdown is temporary: if you charge your phone to 80% or higher, it usually goes away. If it happens repeatedly, your battery needs replacement.

"Battery Health Management is on" means iOS is actively limiting how much charge your battery accepts to slow future degradation. This is a protective feature on newer iPhones. You can turn it off in Settings > Battery > Battery Health & Charging > Battery Health Management, but turning it off will degrade your battery faster.

When to replace your battery versus when to wait

Apple recommends battery service when Maximum Capacity drops below 80% or when Peak Performance Capability shows performance management. However, you do not have to follow this recommendation — many people use phones with lower capacity and accept the faster drain.

Replace your battery if you are charging multiple times a day and it bothers you, or if your phone shuts down unexpectedly even when the battery percentage is not near zero. Do not replace it just because the number dropped — a battery at 75% that lasts all day is fine if that works for your routine.

Battery replacement at an Apple Store costs between $50 and $80 depending on your iPhone model. Third-party repair shops often charge less, but Apple's warranty covers the replacement for one year. If your iPhone is still under AppleCare+, battery service is usually covered at no cost.

How battery health changes over time

A typical iPhone battery loses 1% to 2% of Maximum Capacity per month during the first year, then slows down. After two years, you might see 85% to 90%. After three years, 75% to 85%. These numbers vary widely depending on temperature, charging habits, and how much you use your phone.

You can slow degradation by keeping your phone cool, avoiding extreme heat, and not leaving it plugged in overnight constantly. Charging to 80% instead of 100% and letting it drop to 20% instead of 0% also helps, though the difference is small over a year. Optimized Battery Charging, found in Settings > Battery > Battery Health & Charging, learns your charging routine and stops charging past 80% until you need it — this is worth turning on if you charge overnight.

If your battery drops 10% or more in a single month, something is wrong. Check Settings > Battery to see which apps are using the most power. If one app is draining far more than others, uninstall it or contact the developer. If no single app stands out, your battery may be failing and needs service.

Checking battery health on older iPhones

If you have an iPhone older than iPhone 6s, or if your iPhone runs iOS 16.0 or earlier, the Battery Health & Charging screen does not exist. You can still see limited battery information by going to Settings > Battery > Battery Health, but it will only show Maximum Capacity, not Peak Performance Capability.

For a full diagnostic on older iPhones, you can visit an Apple Store and ask for a battery report, or use a third-party app like Coconut Battery on a Mac or Windows computer. Connect your iPhone to the computer and the app will show detailed battery information including cycle count and design capacity. These apps are informational only — they cannot repair or replace your battery.

What to do if your battery health is poor

If Maximum Capacity is below 80% and you want to replace the battery, you have three options: Apple Store, Apple Authorized Service Provider, or a third-party repair shop. Apple and Authorized Providers use genuine Apple batteries and offer a one-year warranty. Third-party shops are often cheaper but may use non-Apple batteries, which sometimes do not report accurate health information afterward.

Before you go, back up your iPhone to iCloud or a computer. Replacement usually takes one to three hours at an Apple Store, or one to two days at other shops. You will not lose your data — the technician replaces only the battery, not the entire phone.

If your iPhone is still under warranty or AppleCare+, battery service is covered at no cost as long as the battery capacity is below 80%. Check your coverage in Settings > General > About, or on Apple's website by entering your serial number.

Frequently Asked Questions

Is 85% battery health bad?

No. At 85% Maximum Capacity, your battery still holds most of its original charge and usually lasts a full day. You might notice slightly faster drain than when the phone was new, but it is not a sign of failure. Most people do not replace batteries until they drop to 70% or lower.

Can I improve my battery health after it degrades?

No. Battery degradation is permanent — you cannot restore capacity through settings, apps, or charging habits. You can only slow future degradation by keeping your phone cool and avoiding constant full charges. If your battery is already low, replacement is the only way to restore capacity.

Why does my battery health drop so fast?

Fast degradation usually comes from heat, constant charging, or heavy use. If your phone gets hot regularly — from sitting in a car, running demanding apps, or charging in a case — the battery wears faster. Try removing the case while charging, avoiding hot environments, and using Optimized Battery Charging to limit overnight charging.

Do I need to replace my battery if it is at 80%?

No. Apple recommends service at 80%, but you do not have to follow it. If your phone still lasts all day and you are happy with it, you can wait. Replace it when the faster drain actually bothers you or when unexpected shutdowns happen.

Will checking my battery health drain it faster?

No. Opening Settings > Battery > Battery Health & Charging takes a few seconds and uses almost no power. Checking your battery health does not affect the battery itself.