Where to find your iPhone's battery health information

Your iPhone stores a battery health report that you can read in Settings without any tools or apps. Open Settings, then 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 the phone can now 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 the phone needs during heavy use—it will either say "Normal" or describe a limitation.

This screen is the only official way to see battery health on an iPhone. Apple does not provide this information anywhere else in Settings, and third-party apps cannot read the real health data—they can only estimate it based on how fast the battery drains.

Key Takeaways

  • Battery health is found in Settings > Battery > Battery Health & Charging and shows as a percentage of original capacity.
  • Maximum Capacity below 80% usually means the battery is aging and may drain faster than it did when new.
  • Peak Performance Capability shows whether your phone can still run at full speed or has been slowed to protect the battery.
  • Battery health naturally declines over time; a drop to 80–90% after one to two years is normal wear, not a defect.
  • If Maximum Capacity falls below 80% and you are still under warranty or AppleCare+, you may be able to have the battery replaced.

What Maximum Capacity percentage means

Maximum Capacity is a percentage of how much charge your battery can hold compared to when it was brand new. A new iPhone battery is 100%. As you charge and discharge the battery over months and years, the percentage slowly drops.

At 90% capacity, your phone holds 90% of the original charge. If your new iPhone lasted a full day on one charge, a phone at 90% capacity might last about 21.6 hours under the same use. The drop is gradual and usually not noticeable until capacity falls below 80%.

A battery at 80% capacity is still functional and will power your phone for a full day under normal use. Below 80%, you may notice the phone drains noticeably faster, especially if you use demanding apps, play games, or use the camera heavily. At 50% capacity, the battery is significantly degraded and replacement is usually worth considering.

Understanding Peak Performance Capability

Peak Performance Capability describes whether your phone can run at full processor speed or whether iOS has limited the speed to protect an aging battery. It will show one of three states: "Normal", a message about performance management being active, or a message that the battery needs service.

When a battery ages, it sometimes cannot deliver the burst of power the processor needs during heavy use. Instead of crashing, iOS automatically slows the processor down—a feature called performance management. This keeps the phone running but makes it feel slower during demanding tasks. You will see this message if performance management is currently active.

If the message says the battery needs service, the battery has degraded enough that iOS cannot reliably manage performance. The phone may shut down unexpectedly during heavy use even if the battery percentage shows charge remaining. This is a sign that replacement is necessary.

How fast battery health declines and what is normal

Battery capacity naturally declines with every charge cycle. A charge cycle is one full discharge and recharge—from 100% down to 0% and back to 100%. Partial charges count toward a cycle too; two charges from 50% to 100% equal one cycle.

Most iPhone batteries are designed to retain 80% of their capacity after 500 charge cycles. In real use, that usually means 18 to 24 months of daily charging. If you charge your phone every day, you will complete roughly 365 cycles per year, so you might see capacity drop to 90% after one year and 80% after two years. If you charge less often, the decline will be slower.

Temperature also affects battery health. Batteries degrade faster in hot conditions and slower in cool ones. Leaving your phone in a hot car or in direct sun while charging will age the battery more quickly than normal use in moderate temperatures.

When to replace your iPhone battery

If your Maximum Capacity is still above 80% and Peak Performance Capability shows "Normal", your battery is healthy and does not need replacement. You can keep using the phone normally.

If Maximum Capacity has dropped below 80% and you are still within your warranty period or have AppleCare+, Apple will replace the battery at no cost. If you are out of warranty, Apple charges a flat fee for battery replacement (the amount varies by iPhone model). You can start a replacement through Apple's website, at an Apple Store, or through an authorized service provider.

If Peak Performance Capability shows that the battery needs service, replacement is recommended even if Maximum Capacity is still above 80%. A battery in this state may cause unexpected shutdowns during heavy use.

If your phone is several years old and you are considering whether to replace the battery or buy a new phone, compare the battery replacement cost to the cost of a new device. If the phone is otherwise working well and you want to keep it, battery replacement is usually much cheaper.

What you cannot tell from battery health numbers

Battery health percentage does not tell you how long your phone will last on a single charge—that depends on how you use it. A phone at 85% capacity might last all day if you mostly text and browse, but only a few hours if you stream video or play games constantly.

Battery health also does not predict when the battery will fail completely. A battery at 50% capacity will continue to work; it will just drain faster. Batteries do not suddenly stop working when they reach a certain percentage—they degrade gradually.

The numbers also do not account for battery cycles you have already completed. Two phones might both show 85% capacity, but one might have 200 cycles remaining before it drops to 80%, while the other might have 50. The percentage alone does not tell you how much life is left.

How to slow battery aging

You cannot stop battery aging, but you can slow it down by managing heat and charging habits. Keep your phone out of direct sunlight and away from hot environments. Avoid using the phone heavily while it is charging, since this generates heat.

If you plan to store your phone for a long time, charge it to about 50% and keep it in a cool place. Storing a fully charged or fully drained battery in heat will degrade it faster than storing a partially charged battery in cool conditions.

Enabling Optimized Battery Charging in Settings > Battery > Battery Health & Charging can also help. This feature learns your charging patterns and slows charging to 80% overnight, then finishes the last 20% shortly before you wake up. Spending less time at 100% charge reduces stress on the battery and slows aging.

Frequently Asked Questions

Can I check my battery health without going into Settings?

No. The official battery health numbers are only available in Settings > Battery > Battery Health & Charging. Some third-party apps claim to show battery health, but they cannot read the real data—they only estimate based on how fast the battery drains, which is not accurate.

Is 85% battery capacity still good?

Yes. A battery at 85% capacity is still healthy and will power your phone for a full day under normal use. Most people do not notice a difference until capacity drops below 80%. You do not need to replace the battery unless you want to restore it to like-new performance.

Why does my battery health say "Peak Performance Capability: Normal" but the phone feels slow?

Slowness can come from many sources other than battery health—a full storage drive, too many background apps, or an older processor. Battery health is only one factor. If the phone feels slow but battery health is normal, try restarting it, closing unused apps, or freeing up storage space.

What is the difference between a charge cycle and plugging in my phone?

A charge cycle is one full discharge and recharge from 0% to 100%. Plugging in your phone for a partial charge—say, from 40% to 80%—counts toward a cycle but does not complete one. Two partial charges that add up to 100% total equal one cycle.

If my battery health is 50%, will my phone stop working?

No. A battery at 50% capacity will continue to work; it will just drain much faster than a new battery. The phone will not shut down or stop functioning. However, you may need to charge it multiple times per day, and replacement is usually worth considering at this point.