Where to find your iPhone battery health

Open Settings, then tap Battery, then Battery Health & Charging. You will see a percentage labeled Maximum Capacity — that is your battery health. It shows what percentage of the battery's original charge your phone can still hold.

This screen also displays Charging Optimization status and Peak Performance Capability. Peak Performance Capability tells you whether your phone is running at full speed or whether iOS has slowed it down to protect an aging battery from shutting down unexpectedly.

The Battery Health screen is available on iPhone 6 and later. If you have an older model, this information is not available in Settings.

Key Takeaways

  • Maximum Capacity in Settings > Battery > Battery Health & Charging shows what percentage of your battery's original charge remains.
  • A battery at 80 percent capacity or higher is considered normal; below 80 percent means the battery is aging and may need replacement sooner.
  • Peak Performance Capability tells you whether iOS has slowed your phone's processor to prevent unexpected shutdowns on a weak battery.
  • Battery health declines naturally over time and with use; no setting or app can restore it, but you can slow the decline by avoiding extreme temperatures and keeping charge between 20 and 80 percent when possible.

What the percentage actually means

Maximum Capacity is measured as a percentage of the battery's original capacity when the phone was new. A phone showing 85 percent capacity can still hold 85 percent of the charge it held on day one. This does not mean your battery is 15 percent broken — it means the battery has aged and lost some of its ability to store energy.

Apple considers a battery at 80 percent capacity or higher to be in normal condition. Most people do not notice a difference in daily use until capacity drops below 70 percent. At that point, you may notice the phone dies faster than it used to, even when the battery percentage says it should last longer.

Below 50 percent capacity, the battery is significantly degraded. Apple's warranty does not cover normal battery aging, but the company will replace a battery that has fallen below 80 percent capacity for a fee (typically $69 to $99 depending on the model).

What Peak Performance Capability means

Peak Performance Capability describes whether your phone is running at full processor speed. When a battery is weak, iOS can automatically slow down the processor to reduce power demand and prevent the phone from shutting down unexpectedly during a heavy task.

If Peak Performance Capability says "Your battery is unable to support normal peak performance," it means iOS has throttled your processor. The phone will still work, but apps will open more slowly, games will run with lower frame rates, and camera processing will take longer. This slowdown is intentional — it keeps the phone from dying mid-use.

You can turn off this slowdown manually in the same Battery Health screen by toggling off Manage Battery for Peak Performance, but doing so risks unexpected shutdowns when the processor demands more power than the battery can deliver.

How fast battery health declines

Battery capacity typically drops 1 to 2 percent per month under normal use. After two years, most iPhones are at 85 to 90 percent capacity. After three years, 75 to 85 percent is typical. After four years, 65 to 75 percent is common. These numbers vary widely depending on how often you charge, what temperatures you expose the battery to, and how heavily you use the phone.

Lithium batteries degrade faster when they are kept at high temperatures, charged to 100 percent frequently, or drained completely. Batteries also degrade faster if you use the phone while charging it or leave it plugged in overnight regularly. None of these things will destroy a battery overnight, but they add up over months and years.

No app, setting, or cleaning routine can restore battery capacity once it has declined. Battery health only goes down.

When to replace your battery

If your battery is at 80 percent capacity or higher and the phone works normally, there is no urgent reason to replace it. The battery will continue to work; it will straightforward hold less charge than it did when new.

If your battery is below 80 percent and you notice the phone dies faster than it used to, or if Peak Performance Capability shows throttling, you have two options: replace the battery through Apple or an authorized repair shop, or replace the phone. Battery replacement costs $69 to $99 depending on the model. A new phone costs much more but also gives you a new battery, new processor, and new screen.

If your phone is still under warranty or covered by AppleCare+, battery replacement may be free or discounted. Check your coverage in Settings > General > About, then tap the warranty information link.

How to slow battery decline

Keep your phone between 20 and 80 percent charge when possible. Charging from 0 to 100 percent every day ages the battery faster than charging from 30 to 80 percent. You can enable Optimized Battery Charging in Settings > Battery > Battery Health & Charging, which learns your charging habits and slows charging to 80 percent overnight, then finishes the last 20 percent an hour before you usually wake up.

Avoid leaving your phone in hot cars, direct sunlight, or other hot environments for long periods. Batteries degrade faster at temperatures above 95°F (35°C). Cold temperatures slow chemical reactions in the battery but do not permanently damage it; the battery will work normally again once it warms up.

Avoid using the phone while it is charging, especially during heavy tasks like gaming or video recording. This generates heat, which ages the battery faster. If you must use the phone while charging, remove the case first to let heat escape.

Frequently Asked Questions

Can I check my battery health without going into Settings?

No. The Battery Health & Charging screen in Settings is the only official way to see your battery's maximum capacity. Third-party apps cannot read this information. Some apps claim to show battery health, but they are guessing based on how fast your phone drains, which is not the same as actual battery capacity.

Does battery health affect how fast my phone charges?

Not directly. A battery at 50 percent capacity will charge at roughly the same speed as a new battery. However, a very weak battery may not accept a charge as efficiently, so it may feel slower in practice. If your phone charges noticeably slower than it used to, the issue is usually a worn charging cable or port, not the battery.

What does "Charging Optimization" mean?

Charging Optimization is the feature that slows charging to 80 percent overnight and finishes the last 20 percent before you wake up. It learns when you usually charge your phone and when you usually unplug it. This reduces the time the battery spends at 100 percent, which slows aging. You can turn it on or off in Battery Health & Charging settings.

Will my phone stop working if battery health drops below 50 percent?

No. The phone will continue to work, but it will die much faster. A phone at 50 percent capacity might last only a few hours of normal use instead of a full day. It will also be more likely to shut down unexpectedly during heavy tasks, and iOS may throttle performance to prevent this.

Is there a difference between battery health and battery percentage?

Yes. Battery percentage (the number shown in the top right of your screen) tells you how much charge is currently in the battery. Battery health tells you how much total charge the battery can hold. A phone at 20 percent charge with 80 percent health can still hold a full day's worth of power once you charge it. A phone at 100 percent charge with 50 percent health will die much faster.