Where to find your iPhone's 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, then tap Battery, then Battery Health & Charging. You will see a percentage labeled Maximum Capacity — this is the number that tells you how much charge your battery can hold compared to when it was new.
The same screen shows Charging Optimization status and sometimes a message about Battery Condition. These tell you whether iOS is managing your charging to slow wear, and whether Apple has detected any physical problem with the battery itself.
This built-in tool works on iPhone 6 and newer. If you have an older model, you can still see limited battery information by going to Settings > General > About and looking for battery cycle count, though the full health percentage is not available.
Key Takeaways
- Maximum Capacity shows what percentage of the original charge your battery can now hold; 80 percent or higher is normal wear, below 80 percent means the battery is degrading faster than expected.
- You can read your battery health directly in Settings without any third-party tools or visiting an Apple Store.
- Battery Condition warnings appear when Apple detects a physical defect, not just normal aging, and usually mean the battery should be replaced.
- Optimized Charging slows battery wear by learning when you charge and holding the charge at 80 percent until you need it, and you can turn it off if you prefer full charge overnight.
What Maximum Capacity percentage actually means
Maximum Capacity is measured as a percentage of the battery's original design capacity. A new iPhone battery shows 100 percent. As you charge and discharge the battery over months and years, the chemical compounds inside degrade, and the percentage drops. This is normal and happens to every rechargeable battery.
At 80 percent capacity, your battery still holds a useful charge, but you may notice the phone dies faster than it did when new. At 50 percent, the phone may shut down unexpectedly even though the battery indicator shows charge remaining — this is because the battery cannot deliver power fast enough to run the phone's processor.
Apple considers a battery "worn out" when it reaches 80 percent capacity. If your phone is still under warranty or covered by AppleCare+, you may be able to have the battery replaced at no cost. If not, Apple charges a flat fee for battery replacement, which varies by iPhone model but is usually less than the cost of a new phone.
Understanding Battery Condition messages
If your Battery Health screen shows a message under Battery Condition, it means Apple has detected a problem beyond normal wear. The most common messages are "Normal," "Unknown," or "Service Recommended."
Normal means the battery is working as expected for its age. Unknown usually appears after an iOS update and typically clears itself within a few days — it does not indicate a real problem. Service Recommended means the battery has a defect that is not just age-related, and you should contact Apple or visit an Apple Store to discuss replacement.
If you see Service Battery in red text, the battery has failed and the phone may shut down without warning. This is rare and usually only happens if the battery has been physically damaged or exposed to extreme heat. Contact Apple when ready if you see this message.
How Optimized Charging works and whether to use it
Optimized Charging is a feature that learns your charging habits and holds the battery at 80 percent charge until shortly before you wake up or typically use your phone. The idea is that keeping a lithium battery at 100 percent all night causes more wear than charging it only when needed.
If you turn on Optimized Charging, your phone may not reach 100 percent until you pick it up in the morning. This slows battery degradation over time, but some people find it inconvenient if they need a full charge when ready. You can turn it off by going to Settings > Battery > Battery Health & Charging and toggling off Optimized Battery Charging.
Turning off Optimized Charging will not harm your battery in the short term, but leaving it on is the better choice if you charge overnight regularly. The difference in wear is small but measurable over a year or two.
When to replace your battery versus when to replace your phone
If your Maximum Capacity is between 80 and 90 percent and your phone otherwise works well, you do not need to replace the battery yet. Many people use iPhones at 70 or 80 percent capacity without serious problems. Replace the battery when the phone shuts down unexpectedly, when you cannot get through a full day on one charge, or when Battery Condition shows a service message.
Battery replacement is usually cheaper than buying a new phone. Apple's out-of-warranty battery replacement fee ranges from about $50 to $70 depending on the model. If your phone is old enough that the battery is failing, you may also want to consider whether the rest of the hardware is still reliable — a phone with a worn battery and a cracked screen or failing speaker may be worth replacing entirely.
If your phone is still under the one-year limited warranty or you have AppleCare+, battery replacement is usually covered at no cost as long as the battery capacity has dropped below 80 percent or the Battery Condition shows a defect.
Other factors that affect how fast your battery wears
Maximum Capacity depends partly on how you use your phone, not just how old it is. Lithium batteries wear faster when they are regularly charged to 100 percent, left at 100 percent for long periods, exposed to heat, or drained completely to 0 percent. Using your phone while it charges also generates heat and speeds wear.
Cold weather slows chemical reactions inside the battery and can make it seem like capacity has dropped suddenly — the percentage usually bounces back when the phone warms up. Extreme heat, on the other hand, causes permanent damage. Leaving your phone in a hot car or in direct sun for hours can degrade the battery noticeably in a single day.
If you want to slow battery wear, keep your phone between 20 and 80 percent charge when possible, avoid using it while charging, and keep it out of heat. Optimized Charging does much of this automatically if you turn it on.
How to read your battery health if you cannot access Settings
If your phone is frozen, unresponsive, or will not turn on, you cannot read the battery health from Settings. In that case, you can take the phone to an Apple Store or an authorized repair shop, and they can run a diagnostic that shows the battery capacity and any hardware problems.
If the phone turns on but Settings is crashing, try restarting the phone by holding the power button and volume down button together for 10 seconds, then sliding to power off. Wait 30 seconds and turn it back on. If Settings still crashes, you may have a software problem unrelated to the battery, and a backup and restore through a computer or iCloud may fix it.
Frequently Asked Questions
Is 85 percent battery health good?
Yes. Apple considers 80 percent and above normal wear for a battery. At 85 percent, your battery is aging as expected and does not need replacement unless you are having other problems like unexpected shutdowns.
Can I improve my battery health percentage?
No. The percentage reflects chemical degradation inside the battery and cannot be reversed. You can only slow future wear by using Optimized Charging, avoiding heat, and not leaving the phone at 100 percent charge for long periods.
Why did my battery health drop suddenly?
A sudden drop usually means the phone was exposed to heat or cold, or you ran the battery all the way down to 0 percent. Check the Battery Condition message — if it says "Normal," the drop is temporary and the percentage may recover. If it says "Service Recommended," the battery has a defect and should be replaced.
Does a low battery percentage mean my phone will stop working?
Not when ready. A phone at 50 percent capacity still works, but it may shut down unexpectedly under heavy use because the battery cannot deliver power fast enough. At 20 percent or lower, unexpected shutdowns become common and replacement is recommended.
Should I replace the battery or buy a new phone?
If your phone is less than three years old and the rest of it works well, battery replacement is usually the better choice. If the phone is older, has other hardware problems, or is no longer receiving iOS updates, a new phone may be more practical in the long run.