Where to find your iPhone battery health

Your iPhone stores a battery health report built into the system. 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 battery 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 power at full speed, or whether iOS has slowed the phone to protect an aging battery.

This screen is available on iPhone 6 and newer. Older models do not have this built-in report, though third-party apps can estimate battery condition.

Key Takeaways

  • Maximum Capacity shows what percentage of the original charge your battery can hold, and you find it in Settings > Battery > Battery Health & Charging.
  • A battery below 80% maximum capacity may drain noticeably faster and may not power the phone through a full day of use.
  • Peak Performance Capability tells you whether iOS has reduced your phone's speed to protect an aging battery from shutting down unexpectedly.
  • Apple will replace the battery for a flat fee if maximum capacity drops below 80%, though the cost varies by iPhone model.
  • Checking battery health takes 30 seconds and costs nothing; you do not need to visit Apple or use any external tools.

What maximum capacity percentage means for daily use

Maximum Capacity is measured as a percentage of what the battery held when new. At 100%, the battery is at factory condition. At 90%, the battery holds 90% of its original charge. At 80%, it holds 80%.

The drop matters most when you are away from a charger. If your phone used to last a full day at 100% capacity, it will last roughly 80% as long at 80% capacity. A phone that lasted 16 hours might now last 13 hours. The difference becomes noticeable around 85% capacity, when most people start to feel the drain.

Capacity loss is normal and expected. Lithium batteries degrade with every charge cycle—a full discharge and recharge counts as one cycle. Most iPhones lose 10% to 20% capacity in the first two to three years of regular use. This is not a defect; it is how the chemistry works.

Understanding peak performance capability

Peak Performance Capability has two possible states. "Your battery is in normal condition" means the battery can deliver full power and the phone runs at full speed. "Your battery's health is degraded" means iOS has reduced the phone's processing speed to prevent unexpected shutdowns.

When a battery ages, it becomes harder for it to deliver the burst of power the processor needs during heavy tasks. iOS monitors this and, if it detects that the battery cannot keep up, it throttles the processor—slows it down—so the phone draws less power at once. This keeps the phone running instead of crashing. The trade-off is that apps open slower and tasks take longer.

Throttling usually starts when maximum capacity drops below 80%, though it depends on the specific battery condition, not just the percentage. You might see throttling at 82% capacity on one phone and not see it at 75% on another, because the batteries age differently.

When to replace your battery

Apple will replace your battery when maximum capacity falls below 80% or when Peak Performance Capability shows degradation. The cost is a flat fee that varies by iPhone model—typically between $50 and $70 for current models, though older models may cost less or more. You can replace the battery at an Apple Store, an Apple Authorized Service Provider, or by mail-in service.

You do not have to wait until capacity drops to 80%. Some people replace the battery earlier if they notice the phone draining faster than they like. Others wait until the phone no longer lasts a full day. The decision depends on how much time you spend away from a charger and how much the slower performance bothers you.

Third-party repair shops also replace iPhone batteries, often for less money than Apple charges. The trade-off is that third-party batteries may not be genuine Apple parts, and the repair may void your warranty. If your phone is still under warranty or covered by AppleCare+, use Apple or an Authorized Service Provider.

How to slow down battery degradation

Battery degradation is inevitable, but you can slow it down. Keep your phone between 20% and 80% charge when possible—charging to 100% and draining to 0% stresses the battery more than staying in the middle range. If you charge overnight, enable Optimized Battery Charging in Settings > Battery > Battery Health & Charging. This feature learns your charging routine and holds the charge at 80% until shortly before you wake up, then finishes charging to 100%.

Heat damages batteries faster than cold does. Avoid leaving your phone in direct sunlight, in a hot car, or running heavy apps while charging. A phone that runs warm while charging ages faster than one that stays cool. If your phone gets hot during use, close apps and let it cool before charging.

Using the original charger or a certified third-party charger matters less than people think, but a damaged cable or a charger that delivers the wrong voltage can shorten battery life. If your charger is cracked, frayed, or makes the phone unusually warm, replace it.

Checking battery health on older iPhones

iPhones older than the iPhone 6 do not have a built-in battery health report. If you have an iPhone 5s or earlier, you cannot see the exact capacity percentage without taking the phone to Apple or using a third-party diagnostic tool.

Some third-party apps claim to show battery health, but they estimate based on indirect measurements and are not as accurate as Apple's built-in report. If you own an older iPhone and want to know the real battery condition, visit an Apple Store or Apple Authorized Service Provider. They can run a diagnostic and tell you the exact capacity.

What happens if you ignore a degraded battery

If maximum capacity drops very low—below 50%—the phone may shut down unexpectedly during heavy use, even if the battery percentage shows 20% or higher. This happens because the battery cannot deliver the power the processor needs, so iOS cuts power to protect the battery from damage. The phone turns off, and you have to charge it to turn it back on.

This is frustrating but not dangerous. The phone is not broken; the battery straightforward cannot do the job anymore. Replacing the battery fixes the problem. Until then, you can reduce unexpected shutdowns by closing background apps, lowering screen brightness, and avoiding heavy tasks like gaming or video recording when the battery is below 30%.

Frequently Asked Questions

Is 85% battery health still good?

Yes. Most people do not notice a difference until capacity drops below 80%. At 85%, the battery holds 85% of its original charge, so if your phone lasted 16 hours new, it will last roughly 13.6 hours now. You may notice the phone drains faster than it used to, but it should still last a full day with normal use.

Can I improve battery health after it degrades?

No. Battery degradation is permanent and chemical. Optimized Battery Charging, reducing heat, and avoiding extreme charge cycles slow future degradation, but they cannot restore capacity that has already been lost. The only way to restore battery health to 100% is to replace the battery.

Why does my battery health drop so fast?

Fast degradation usually comes from heat, frequent full charges to 100%, or deep drains to 0%. If you charge your phone in a hot environment, leave it in the sun, or regularly drain it completely, the battery will age faster. Turning off Optimized Battery Charging also speeds degradation. Check your charging habits and environment first before assuming the battery is defective.

Does Apple replace the battery for free?

No. Apple charges a flat fee for battery replacement, typically $50 to $70 depending on the model. If your phone is under warranty and the battery has a manufacturing defect, Apple may replace it at no cost, but normal degradation is not covered. AppleCare+ includes battery service, so if you have that plan, battery replacement is covered.

Should I replace my battery or buy a new phone?

That depends on the phone's age and condition. If the phone is two to four years old and the battery is the main problem, replacement is usually worth it—a new battery costs $50 to $70 and can add another year or two of life. If the phone is five years old or older, or if other parts are failing, a new phone may make more sense financially.