Where to find your iPhone battery health right now
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 it can still hold. Peak Performance Capability tells you whether the phone is running at full speed or if iOS has slowed the processor to protect an aging battery.
This screen is available on iPhone XS and newer. If you have an older model, you can still see limited battery information in Settings > Battery > Battery Health, but it will not show the percentage.
The numbers update once per day, usually overnight. If you just replaced your battery through Apple or an authorized repair shop, the capacity should read close to 100 percent within a day or two.
Key Takeaways
- Maximum Capacity below 80 percent means your battery is degraded and Apple will replace it for a fee if you are out of warranty.
- Peak Performance Capability shows whether iOS has throttled your processor; if it says "Standard", your phone is running at full speed.
- Batteries degrade naturally over time and charge cycles, and no setting or app can reverse that degradation.
- If your phone shuts down unexpectedly even when the battery shows charge, that is a sign the battery needs replacement soon.
What Maximum Capacity actually means
Maximum Capacity is the percentage of the original charge your battery can still hold. A new iPhone battery is rated at 100 percent. After 500 full charge cycles, Apple's design target is 80 percent capacity. After 1,000 cycles, it typically drops to around 60 to 70 percent.
A charge cycle is one full drain from 100 percent to 0 percent, or the equivalent spread across multiple days. Charging from 50 to 100 percent counts as half a cycle. Most people complete one cycle every one to two days, so a battery lasts roughly two to three years before hitting 80 percent.
At 80 percent capacity, the battery still works, but it holds less charge than it did new. Your phone will not last as long between charges. Below 80 percent, Apple considers the battery degraded and will replace it for a fee outside of warranty.
What Peak Performance Capability means and why it matters
Peak Performance Capability has three possible states: Standard, Reduced, or a message saying the battery needs service. Standard means your phone is running at full processor speed. Reduced means iOS has lowered the processor speed to prevent unexpected shutdowns on a battery that can no longer deliver peak power reliably.
iOS applies this slowdown automatically when it detects that a degraded battery cannot supply the current the processor demands at full speed. The slowdown is not permanent damage — it is a protection measure. If you replace the battery, Peak Performance Capability will return to Standard within a day or two.
If the screen says your battery needs service, the battery is in poor condition and Apple recommends replacement. This does not mean your phone will stop working when ready, but the battery is no longer reliable.
Why your battery degrades and what you cannot fix
Lithium-ion batteries degrade every time they charge and discharge. This is chemistry, not a defect. Heat, age, and the number of charge cycles all speed up degradation. There is no setting, app, or charging method that can reverse this process or stop it entirely.
Keeping your phone cooler, avoiding full discharges, and charging to 80 percent instead of 100 percent can slow degradation slightly. iOS 15.1 and newer include an Optimized Battery Charging feature that learns your charging patterns and holds the battery at 80 percent until you need it, which can extend battery lifespan by a few months. You can turn this on in Settings > Battery > Battery Health & Charging > Optimized Battery Charging.
But these steps only delay the inevitable. After two to three years of normal use, your battery will reach 80 percent capacity, and replacement is the only way to restore it.
When to replace your battery versus when to replace your phone
If your Maximum Capacity is above 80 percent and Peak Performance Capability is Standard, your battery is healthy and you do not need to replace it yet. If it is below 80 percent but your phone still lasts a full day on a charge, you can wait to replace it.
Replace the battery if your phone shuts down unexpectedly even when the battery shows 20 to 40 percent charge remaining. This means the battery cannot deliver the power the phone needs, even though it still holds charge. Replacement costs between $69 and $99 at Apple, depending on your model, and takes one to two hours at an Apple Store or authorized repair shop.
If your phone is more than five years old, the processor and other components may also be aging. In that case, replacing the battery might extend the phone's life by one to two years, but you may eventually want to upgrade. If your phone is two to three years old and the battery is the only problem, replacement is usually the better choice.
How to read the battery health screen on older iPhones
iPhone XS, XS Max, XR, and newer show both Maximum Capacity and Peak Performance Capability. iPhone X and earlier show only a message in Settings > Battery > Battery Health that says either "Your battery is in good condition" or "Your battery's health is significantly degraded."
On older models, you cannot see the exact percentage. If the message says the battery is significantly degraded, it is below 80 percent capacity. If it says the battery is in good condition, it is above 80 percent. You do not get more detail than that without using a third-party app or taking the phone to Apple.
If you want the exact percentage on an older iPhone, Apple's Genius Bar can tell you during a free diagnostic. Some third-party apps claim to show battery health, but they cannot access the real data — they estimate based on usage patterns and are often inaccurate.
What to do if your battery health is poor
If Maximum Capacity is below 80 percent, you have two choices: replace the battery or replace the phone. Battery replacement at Apple costs $69 for iPhone 15, $79 for iPhone 14 and 13, and $89 for iPhone 12 and 11. Older models may cost more or be unavailable for service.
You can also use a third-party repair shop, which may charge less but may not use genuine Apple parts. Genuine batteries come with a one-year warranty. Third-party batteries may not be covered by Apple's warranty, and some may not perform as well.
If your phone is still under AppleCare+, battery replacement is covered at no cost if the capacity has dropped below 80 percent. Check your coverage in Settings > General > About > Limited Warranty or by visiting apple.com and signing in with your Apple ID.
Frequently Asked Questions
Can I see my battery health without going to Settings?
Not on the main screen. You must open Settings, tap Battery, then Battery Health & Charging. Some older iPhones show a low battery warning in the status bar, but that is not the same as battery health — it just means your charge is low right now.
Does a lower Maximum Capacity mean my phone will break soon?
No. A battery at 60 percent capacity still works. It just holds less charge, so your phone will not last as long between charges. Many people use phones with 50 to 60 percent capacity for another year or more. Replacement is a choice, not an emergency, unless the phone shuts down unexpectedly.
Will replacing my battery fix Peak Performance Capability if it says Reduced?
Yes. Once you replace the battery, Peak Performance Capability will return to Standard within a day or two. iOS applies the slowdown only when it detects a degraded battery, so a new battery removes the reason for the slowdown.
Is there an app that shows more detailed battery information?
Third-party apps cannot access the real battery health data that Apple's system uses. They can show you charge cycles and temperature, but they estimate battery capacity based on usage patterns and are often wrong. The Settings screen is the only reliable source.
What if my battery health is 100 percent but my phone still drains fast?
Fast drain with healthy battery capacity usually means an app is using too much power, or your screen brightness is high. Check Settings > Battery > Battery Usage to see which apps are draining the most power. You can also lower screen brightness or enable Low Power Mode to extend battery life without replacing the battery.