Your iPhone battery degrades over time and loses the ability to hold a charge
Every iPhone battery is designed to retain 80 percent of its original capacity after 500 complete charge cycles. A charge cycle means draining the battery from full to empty and charging it back to full — not necessarily in one day. After that point, the battery continues to work, but it holds less energy with each cycle, and your phone may shut down unexpectedly even when the battery percentage shows 20 or 30 percent remaining.
You do not need to replace your battery the moment it drops below 80 percent. Most people can use their phone normally until the battery capacity falls to around 70 percent or lower, or until the unexpected shutdowns become frequent enough to disrupt your day. The decision to replace depends on how much the degradation bothers you and how long you plan to keep the phone.
Apple and most repair shops can tell you the exact battery health percentage of your iPhone. This number is the most reliable way to know whether replacement makes sense for your situation.
Key Takeaways
- Check your battery health percentage in Settings > Battery > Battery Health and Charging to see the actual degradation, not just the percentage shown on your screen.
- Battery capacity below 80 percent is normal wear; replacement becomes worth considering around 70 percent or when unexpected shutdowns happen regularly.
- An out-of-warranty battery replacement at Apple costs between $69 and $99 depending on your iPhone model, and takes one to two hours at most locations.
- Third-party repair shops often charge less but may use non-Apple batteries, which can affect performance and future software updates.
How to check your battery health right now
Open Settings on your iPhone and go to Battery, then Battery Health and Charging. You will see two numbers: the maximum capacity percentage and the peak performance capability. The maximum capacity is what matters for deciding whether to replace — this is the percentage of the original battery charge your phone can still hold.
If the maximum capacity shows 100 percent, your battery is new or nearly new. At 90 percent, you have normal wear from regular use. At 80 percent, you are at the threshold where Apple considers the battery degraded. Below 80 percent, the battery is aging faster than expected, either from heavy use, heat exposure, or age.
The peak performance capability line tells you something different: whether your phone is throttling its processor to prevent unexpected shutdowns. If this line says "Your battery is in good condition" or similar, your phone is running at full speed. If it says your phone has experienced unexpected shutdowns and is now running slower, that is a sign the battery needs attention soon, regardless of the capacity percentage.
When unexpected shutdowns mean you should replace the battery
An unexpected shutdown happens when your iPhone powers off even though the battery percentage shows 20, 30, or sometimes 40 percent remaining. This occurs because the battery cannot deliver the power the phone needs in that moment, even though it has stored energy left. It is not a software glitch — it is a hardware limitation of an aging battery.
If this happens once or twice a month, you can usually live with it by keeping your phone charged above 30 percent. If it happens multiple times a week, or if it happens during tasks you rely on your phone for, replacement becomes practical rather than optional. One unexpected shutdown during a navigation app or a work call is often enough to make people decide the battery is worth replacing.
Check your Settings again after an unexpected shutdown. The peak performance capability section will now show that your phone has experienced unexpected shutdowns and may be running slower. This message confirms the battery is the cause, not a software problem.
Battery replacement costs and where to get it done
Apple charges $69 to $99 for an out-of-warranty battery replacement, depending on your iPhone model. Older models like the iPhone 11 cost less; newer models like the iPhone 15 cost more. The replacement usually takes one to two hours at an Apple Store, though some locations can do it the same day if you walk in without an appointment. You can also schedule a Genius Bar appointment online to avoid waiting.
If your iPhone is still under the one-year limited warranty and the battery capacity has dropped below 50 percent, Apple will replace it for free. Check your purchase date in Settings > General > About to see if you are still covered. AppleCare+ extends this coverage to two years and also covers accidental damage, though it costs extra upfront.
Third-party repair shops like Best Buy's Geek Squad, local independent repair shops, and mail-in services often charge $30 to $60 for battery replacement. The trade-off is that some use non-Apple batteries, which may not perform identically and could trigger warnings in future iOS updates. Ask the shop whether they use Apple batteries or third-party equivalents before you commit.
What happens to your phone after battery replacement
After replacement, your maximum capacity percentage resets to 100 percent, and your phone behaves like a new device in terms of battery life. You will notice the phone holds a charge longer and no longer shuts down unexpectedly. The replacement battery itself is designed to last another 500 charge cycles before degradation becomes noticeable again.
If you had AppleCare+ coverage, the replacement is free. If you did not, you pay the out-of-warranty fee at the time of service. Apple does not charge extra for labor — the price quoted is the total cost. You do not need to back up your phone or erase anything; the battery replacement does not touch your data or settings.
One thing to know: if you had your battery replaced at a third-party shop using a non-Apple battery, iOS may occasionally show a warning that the battery is not genuine. This does not prevent the phone from working, but it can be annoying. Some people choose to replace the battery again at Apple later to eliminate the warning.
How to slow down battery degradation before replacement becomes necessary
Battery degradation is inevitable, but you can slow it down by managing heat and charge cycles. Keep your phone out of direct sunlight and away from hot environments like a car dashboard in summer. Heat is the single biggest factor that speeds up battery aging, more than the number of times you charge it.
Enable Optimized Battery Charging in Settings > Battery > Battery Health and Charging. This feature learns your charging patterns and slows down charging to 80 percent overnight, then finishes the last 20 percent right before you wake up. This reduces the time the battery spends at 100 percent, which is when degradation happens fastest. The feature is on by default on most iPhones.
Avoid letting your battery drain completely to zero regularly. Charging from 20 percent to 80 percent is gentler on the battery than draining it fully and charging to 100 percent. You do not need to obsess over this — normal use is fine — but if you notice you often let your phone die completely, plugging it in earlier will extend the battery's life.
Deciding whether to replace the battery or upgrade your phone
If your iPhone is less than three years old and the battery capacity is above 70 percent, battery replacement usually makes financial sense. You will get another two to three years of reliable use for $70 to $100. If your phone is five years old or older, consider whether you want to keep it at all — the battery is one of several components that age, and other repairs may be needed soon.
If your battery capacity is below 50 percent and your phone is more than four years old, the cost of replacement plus potential future repairs may approach the cost of a used phone of the same model in good condition. Check the price of a used iPhone matching your current model to compare. Sometimes replacing the battery is the better choice; sometimes upgrading makes more sense.
One practical test: if the unexpected shutdowns are the only thing bothering you about your phone, and everything else works normally, battery replacement is worth doing. If you are also frustrated with speed, camera quality, screen brightness, or other features, those problems will not improve with a new battery, and upgrading might be the better path.
Frequently Asked Questions
Can I replace my iPhone battery myself?
Apple does not sell batteries to consumers for self-installation, and opening your iPhone yourself voids the warranty and risks damaging the water-resistance seal. If you are comfortable with electronics repair, third-party batteries and tools are available online, but this approach carries real risk of breaking other components. For most people, paying for professional replacement is safer and faster.
Does a new battery fix a slow iPhone?
Only if the slowness is caused by battery throttling. Check Settings > Battery > Battery Health and Charging — if the peak performance section says your phone is running slower due to unexpected shutdowns, a new battery will restore full speed. If your phone is slow for other reasons, a new battery will not help.
How long does a battery replacement take at Apple?
Most replacements take one to two hours. If you schedule a Genius Bar appointment, you can often pick up your phone the same day. Walk-in service may take longer depending on how busy the store is. Mail-in service through Apple takes about a week total, including shipping time.
Will my data be erased if I replace the battery?
No. Battery replacement does not touch your data, settings, or apps. Your phone will have the same content and configuration after the replacement as it did before. You do not need to back anything up.
What is the difference between battery capacity and battery health?
Battery capacity is the percentage of the original charge your battery can still hold — this is the number that matters for deciding whether to replace. Battery health is a broader term that includes capacity plus the battery's ability to deliver power without unexpected shutdowns. You can have 85 percent capacity but poor health if the battery is failing in other ways.