Replace your iPhone battery when it drops below 80% health, or sooner if you notice rapid drain, unexpected shutdowns, or swelling

Apple considers an iPhone battery at 80% health or above to be in normal condition. Once it falls below 80%, the battery has completed roughly 500 charge cycles and has begun to lose its ability to hold a full charge. You do not have to wait until it reaches 80%—many people replace batteries at 85% or 90% if they use their phone heavily—but 80% is the threshold where Apple's warranty covers battery replacement.

The percentage you see in Settings does not tell the whole story. A battery at 82% health might still drain in two hours if you are running demanding apps, while one at 75% might last a full day if you use your phone lightly. The real question is whether your phone still does what you need it to do. If it does not, replacement makes sense regardless of the percentage.

Key Takeaways

  • Check your battery health in Settings > Battery > Battery Health & Charging to see the actual percentage your iPhone reports.
  • Apple covers battery replacement under warranty if health is below 80%, but you can replace it at any percentage if performance has declined.
  • Unexpected shutdowns, rapid drain during normal use, and visible swelling are signs to replace the battery when ready, even if health percentage seems acceptable.
  • Battery replacement costs between $50 and $100 depending on your iPhone model, and takes one to three days at an Apple Store or authorized repair shop.
  • Turning off background app refresh, reducing screen brightness, and enabling Low Power Mode can extend battery life without replacement.

How to check your iPhone battery health percentage

Open Settings, then tap Battery, then Battery Health & Charging. You will see a number labeled "Maximum Capacity"—that is your battery health percentage. It represents how much charge your battery can hold compared to when it was new. A phone fresh from the factory shows 100%. Over time, this number drops as the battery ages.

The same screen shows "Condition" below the percentage. If it says "Normal," your battery is functioning as expected for its age. If it says "Service Recommended," Apple is telling you the battery has degraded enough that you may want to replace it. If it says "Service Not Available," the battery may be damaged or counterfeit, and you should contact Apple or an authorized repair shop.

Battery health thresholds and what they mean

A battery at 100% is brand new. Between 95% and 100%, you will notice no difference in daily use. At 90% to 95%, the battery is still performing well for most people, though heavy users may start to see shorter battery life. At 80% to 90%, the battery is aging normally and may need replacement within the next year or two, depending on how much you use your phone.

Below 80%, the battery is degrading faster. At 70% to 80%, you may notice the phone drains noticeably faster than it did a few months ago. Below 70%, most people experience significant battery drain and may see unexpected shutdowns even when the phone shows 20% or 30% charge remaining. Below 50%, the phone becomes difficult to use for more than a few hours without charging.

Warning signs that mean replace the battery now

Do not wait for the percentage to drop if you see these signs: your phone shuts down suddenly even though the battery shows 30% or higher charge; the phone gets warm or hot during normal use; the battery drains 10% or more per hour when you are not actively using it; or the back of the phone feels swollen or the screen has lifted slightly from the frame.

Unexpected shutdowns are the most common warning sign. This happens because the battery cannot deliver the power the phone needs, even though it still holds charge. Swelling is a safety issue—a swollen battery can damage the phone's internal components and poses a small fire risk. If you see swelling, stop using the phone and take it to Apple or an authorized repair shop when ready. Do not try to open the phone yourself.

Cost and time for battery replacement

Apple charges $69 for battery replacement on most iPhone models, though some newer models cost up to $99. If your phone is under warranty and the battery health is below 80%, Apple covers the replacement at no cost. If you have AppleCare+, battery replacement is also covered. Without warranty or AppleCare+, you pay the full amount.

Authorized repair shops—including some Best Buy locations and independent repair stores—often charge $50 to $80 for the same service. Replacement usually takes one to three days at an Apple Store, depending on how busy they are. Some authorized shops can do it the same day. If you use a mail-in repair service, add three to five days for shipping both ways.

How to extend battery life without replacement

If your battery health is still above 80% but you are seeing faster drain than usual, try these steps before replacing the battery. Go to Settings > Battery and look at Battery Usage by App—apps using more than 10% of your battery in a day are worth closing or uninstalling. Turn off Background App Refresh for apps you do not need to update constantly: Settings > General > Background App Refresh.

Enable Low Power Mode in Settings > Battery to reduce performance and screen brightness automatically. Turn off location services for apps that do not need it: Settings > Privacy > Location Services. Reduce screen brightness or enable Auto-Brightness: Settings > Display & Brightness. These changes will not restore a degraded battery to like-new condition, but they can add hours to your daily battery life while you decide whether to replace it.

What happens after you replace the battery

After replacement, your battery health will show 100% in Settings. The phone will charge faster and last longer on a single charge. If you were experiencing unexpected shutdowns, those will stop when ready. The phone will also run cooler because the battery is no longer struggling to deliver power.

Your battery health will begin to drop again as soon as you start using the phone. This is normal. A new battery typically drops to 95% within the first month and reaches 80% after 500 to 600 full charge cycles, which takes roughly two to three years of normal use. You can slow this decline by avoiding extreme temperatures, not leaving the phone plugged in overnight constantly, and using Low Power Mode when the battery is below 20%.

Frequently Asked Questions

Can I replace my iPhone battery myself?

You can, but it is difficult and voids your warranty. iPhone batteries are glued in place, and removing them requires heat, special tools, and careful handling to avoid damaging the screen or internal components. Unless you have experience with phone repair, take it to Apple or an authorized shop. The cost is low enough that the risk of breaking something more expensive is not worth it.

Does battery health affect phone performance?

Yes. As battery health drops, the phone may slow down to prevent unexpected shutdowns. This is called performance throttling. Once you replace the battery, the phone will run at full speed again. You can check if throttling is active in Settings > Battery > Battery Health & Charging—if it says "Peak Performance Capability," throttling is not happening.

Why does my battery health drop so fast?

Heavy use, frequent charging, and high temperatures all speed up battery degradation. If you charge your phone multiple times a day or leave it plugged in constantly, the battery will reach 80% health faster than someone who charges once a day. Keeping your phone in a hot car or using it while it is charging also accelerates wear. Try charging to 80% and stopping, or use Optimized Battery Charging in Settings > Battery > Battery Health & Charging to limit charging to 80% overnight.

Is it worth replacing the battery or should I just buy a new phone?

If your phone is less than four years old and works well otherwise, battery replacement is worth it. A new battery costs $50 to $100 and gives you another two to three years of use. A new phone costs $800 or more. If your phone is five years or older, the decision depends on whether other parts are failing—if the screen, camera, or charging port are also having problems, a new phone may make more sense.