Check battery capacity in Settings on any iPhone
Open Settings, then tap Battery or Battery and Device Management (depending on your iOS version). On the next screen, select Battery Health & Charging. You will see Maximum Capacity listed as a percentage — this is your battery's current capacity compared to when it was new.
Maximum Capacity tells you how much charge your battery can hold right now. A new iPhone battery is at 100%. Over time, all lithium batteries lose capacity. If your iPhone shows 80% maximum capacity, the battery can hold 80% of the charge it held when new. This is normal wear; Apple considers a battery degraded once it drops below 80%.
The same screen also shows Battery Health status — either "Normal" or a message about reduced performance. "Normal" means your battery is working as expected for its age. Other messages indicate the battery needs service.
Key Takeaways
- Maximum Capacity percentage in Battery Health & Charging shows how much charge your battery can hold compared to when it was new.
- A battery at 80% capacity or higher is considered healthy; below 80% is normal degradation but Apple may recommend service at lower percentages.
- Battery Health status on the same screen tells you whether your battery is performing normally or has a problem that needs attention.
- Capacity drops over time with normal use — this is expected and does not mean your phone is broken.
What the percentage actually means
The percentage is not the current charge in your phone right now. It is the total amount of energy your battery can store. If your iPhone shows 85% maximum capacity and you charge it to 100%, you are filling 85% of what the battery could hold when new — not 85% of a full charge.
Think of it like a water tank. A new tank holds 100 gallons. After years of use, the same tank might only hold 85 gallons even when completely full. The percentage tells you the tank's condition, not how much water is in it today.
Why capacity drops over time
Lithium batteries degrade with every charge cycle — one cycle is a full discharge and recharge. After 500 to 1,000 cycles (depending on the iPhone model and how you use it), most batteries lose 10 to 20% of their capacity. This is chemical wear, not a defect.
Heat, fast charging, and letting the battery drain completely also speed up degradation. iPhones manage this by slowing down performance when the battery is very degraded, to prevent unexpected shutdowns. That slowdown is separate from capacity loss — you might see reduced performance even if capacity is still above 80%.
When to consider a battery replacement
Apple recommends service when maximum capacity drops below 80% and the phone is still under warranty or AppleCare+. If your iPhone is out of warranty, you can still get a replacement battery through Apple or an authorized repair shop, though you will pay out of pocket.
You do not have to replace the battery the moment it hits 80%. Many people use iPhones with 70% or 60% capacity without problems. Replace it when the phone no longer holds a charge long enough for your day, or when Battery Health shows a message other than "Normal."
Battery Health messages and what they mean
If Battery Health shows anything other than "Normal," the message will explain the issue. Common messages include "Battery Degraded" (the battery is wearing out faster than expected), "Service Recommended" (capacity is very low), or "Service Battery" (the battery needs replacement soon). Some iPhones also show "Charging Unavailable" if the battery has a fault that prevents charging.
These messages do not mean your phone will stop working when ready. They tell you the battery is not performing as it should and you may want to plan a repair. If you see "Service Battery," the phone may shut down unexpectedly if the battery is very low, so plan the repair sooner rather than later.
How to slow down battery degradation
Keep your iPhone between 20% and 80% charge when possible — avoid letting it drain to 0% or sitting at 100% for long periods. Avoid heat; do not leave your phone in a hot car or in direct sun for hours. Use standard charging rather than fast charging when you have time, though modern iPhones are designed to handle fast charging safely.
Enable Optimized Battery Charging in Battery Health & Charging settings. This feature learns your charging habits and slows down charging to 80% until you need the phone, then finishes the last 20% closer to when you wake up. It reduces the time your battery spends at 100%, which slows degradation.
Frequently Asked Questions
Can I check battery capacity without going into Settings?
No. The only way to see maximum capacity is through Settings > Battery > Battery Health & Charging. Third-party apps cannot read this information. Some apps claim to show battery health, but they are guessing based on usage patterns, not reading the actual battery data.
Does low battery capacity mean my phone is broken?
No. Battery degradation is normal wear. A battery at 60% capacity is old but not broken — it just holds less charge. Your phone will work fine; it will straightforward need charging more often. Replace the battery only when the reduced capacity affects your daily use.
Why does my iPhone slow down even though capacity is still above 80%?
iOS can reduce performance for reasons other than low capacity — for example, if the battery cannot deliver power fast enough under heavy load, or if the phone is too hot. Check Battery Health for the specific message. If it says "Normal," the slowdown is likely from heat, background apps, or storage being full.
How long does a typical iPhone battery last before needing replacement?
Most iPhone batteries reach 80% capacity after two to three years of normal use. This varies based on how often you charge, whether you use fast charging, and how hot the phone gets. Some people see 80% after one year; others stay above 80% for four years.
Is it worth replacing the battery myself?
Apple and authorized repair shops have the right tools and parts. DIY battery replacement risks damaging the phone's water resistance, screen, or internal components. If cost is a concern, check whether your phone is still under warranty or AppleCare+, which covers battery replacement at no charge.