How to know when your iPhone battery needs replacing

Your iPhone battery degrades over time, and you'll notice it through everyday use before you need to take it in. The most common sign is that your phone shuts down at 20 or 30 percent battery, even though the percentage display says it should have more charge left. Another early warning is that your phone gets noticeably warm during normal use—texting, browsing, or light apps—not just during video or gaming. If you're charging your phone twice a day when you used to charge it once, or if apps close unexpectedly when you switch between them, your battery is likely wearing out.

Apple includes a battery health tool built into every iPhone that shows you the exact condition of your battery. Go to Settings, then Battery, then Battery Health & Charging. You'll see a percentage labeled "Maximum Capacity"—this tells you how much charge your battery can hold compared to when it was new. A battery at 80 percent capacity or higher is still healthy. Between 80 and 70 percent, you're in the zone where replacement becomes worth considering. Below 70 percent, replacement is usually the right move.

Key Takeaways

  • Check your battery health in Settings > Battery > Battery Health & Charging; a maximum capacity below 70 percent means replacement is worth considering.
  • Your phone shutting down at 20–30 percent battery, running warm during normal use, or needing two charges per day are all signs of battery wear.
  • Battery replacement costs between $50 and $100 depending on your iPhone model, and takes one to three days at most repair locations.
  • Apple's one-year warranty covers battery replacement only if capacity drops below 80 percent within that year; AppleCare+ extends coverage to two years.
  • Third-party repair shops often charge less than Apple but may void your warranty, so compare pricing and warranty terms before choosing.

What the battery health percentage actually means

The maximum capacity percentage in Battery Health & Charging is the most reliable number you have. It measures how much total charge your battery can store right now versus the day it left the factory. A new iPhone battery is at 100 percent. After one year of normal use, most iPhones sit between 95 and 98 percent. After two years, expect 85 to 92 percent. After three years, 75 to 85 percent is typical.

Apple considers a battery "degraded" once it drops below 80 percent capacity within the first year—that's the threshold for warranty coverage. This doesn't mean your phone is broken or unusable at 79 percent; it means Apple will replace it for free if you're still under warranty. At 70 percent or lower, your phone will feel noticeably slower during heavy use, and unexpected shutdowns become more frequent. Between 70 and 80 percent, you're in a gray zone where replacement depends on how much the slowdowns bother you and how long you plan to keep the phone.

When to replace before the battery fails completely

You don't have to wait for your battery to fail. In fact, replacing it before it reaches 50 percent capacity is usually smarter, because a severely degraded battery can cause your phone to slow down dramatically—Apple throttles performance on iPhones with weak batteries to prevent unexpected shutdowns. If your battery is at 60 percent capacity and you plan to keep your phone for another year or two, replacement now will restore the speed and reliability you had when the phone was new.

The best time to replace is when your battery hits 70 percent capacity and you're noticing real slowdowns in daily use. At that point, you've gotten good life out of the battery, and replacement will cost you $50 to $100 depending on your model—much less than buying a new phone. If your battery is still above 80 percent but you're seeing unexpected shutdowns, that's also worth investigating; sometimes the issue is software rather than hardware, so restart your phone and check for pending iOS updates before scheduling a replacement.

Warranty coverage and repair costs

Apple's standard one-year warranty covers battery replacement if your maximum capacity drops below 80 percent during that first year. You pay nothing for the replacement itself, though you may pay a small fee if you need expedited service. If you purchased AppleCare+, coverage extends to two years and includes accidental damage, so battery replacement remains free throughout that period.

Without warranty coverage, Apple charges $69 for battery replacement on most current iPhone models, though older models may cost slightly less. The repair takes one to three business days at an Apple Store or Apple Authorized Service Provider. Third-party repair shops—both local independent shops and mail-in services—often charge $40 to $60, sometimes less. The trade-off is that third-party repair may void your remaining warranty on other components, and the quality of the replacement battery can vary. Always ask whether the shop uses genuine Apple batteries or third-party equivalents before you commit.

How to extend battery life before replacement

While you're deciding whether to replace your battery, you can slow its degradation and improve daily performance. Enable Low Power Mode in Settings > Battery—it reduces background activity and limits performance slightly, but extends the time between charges. Keep your phone cool; heat accelerates battery wear, so avoid leaving it in direct sunlight or in a hot car. Charge your phone to 80 percent most days rather than all the way to 100 percent; the last 20 percent of charge causes the most stress on the battery chemistry.

Update to the latest iOS version available for your phone. Apple regularly releases updates that improve battery efficiency and fix software issues that drain power unnecessarily. If you're seeing rapid battery drain despite a healthy maximum capacity percentage, a pending iOS update or a misbehaving app may be the culprit rather than the battery itself. Check Settings > Battery > Battery Usage to see which apps are consuming the most power, and consider uninstalling or updating any that seem excessive.

Choosing between Apple and third-party repair

Apple Stores and Apple Authorized Service Providers use genuine Apple batteries and offer a warranty on the replacement—usually 90 days. They're the safest choice if you want to be certain the battery is authentic and if you have remaining AppleCare+ coverage. The downside is cost and wait time; Apple charges more, and you may need to book an appointment days in advance.

Third-party repair shops—whether local or mail-in—are faster and cheaper. Many use genuine Apple batteries salvaged from other repairs, while others use high-quality third-party batteries that perform nearly identically. The risk is that a poor-quality replacement battery may degrade faster than an Apple battery, and your phone's warranty on other components may be affected. Before choosing a third-party shop, read recent reviews, ask whether they use genuine or third-party batteries, and confirm what warranty they offer on the replacement. Some shops offer a one-year warranty on the battery itself, which is a good sign.

What happens if you ignore a degraded battery

A degraded battery won't suddenly explode or catch fire—that's extremely rare. What will happen is increasing inconvenience: unexpected shutdowns when you're away from a charger, slower performance during heavy use, and the need to charge more frequently. Your phone will still work, but it will feel like an older device. If your battery reaches 50 percent capacity or lower, performance throttling becomes severe, and even straightforward tasks like opening the camera or sending a text may feel sluggish.

The longer you wait, the more you'll feel the effects. If you plan to keep your phone for another two years, replacing the battery now is much cheaper than buying a new phone later. If you're planning to upgrade to a new phone within six months anyway, you can skip the replacement and live with the slowdowns. The decision comes down to how long you want to keep the phone and how much the performance loss bothers you in daily use.

Frequently Asked Questions

Can I replace my iPhone battery myself?

You can, but it's difficult and risky for most people. iPhones are sealed with adhesive, and opening one requires heat, special tools, and careful technique to avoid damaging the screen or internal components. If you damage something during the process, repair costs will far exceed the cost of professional replacement. Unless you have experience with phone repair, professional replacement is the safer and often cheaper option.

How long does a battery replacement take?

At an Apple Store or authorized service provider, battery replacement usually takes one to three business days. Some locations offer same-day service if you drop it off early in the morning. Third-party repair shops vary; local shops may do it in a few hours, while mail-in services take five to seven business days including shipping time. Call ahead to ask about turnaround time before you commit.

Will replacing the battery make my phone feel new again?

Yes, in terms of battery life and performance. A new battery will restore the charge time and runtime you had when the phone was new, and it will eliminate the performance throttling that comes with a degraded battery. The screen, camera, and other components won't change, so the phone won't feel brand new in every way—but daily usability will improve noticeably.

What if my battery health is at 85 percent but my phone shuts down unexpectedly?

Unexpected shutdowns at a relatively high battery health percentage usually point to a software issue rather than battery wear. Restart your phone, check for pending iOS updates, and review which apps are using the most battery in Settings > Battery > Battery Usage. If the problem persists after updating, contact Apple Support or visit an Apple Store to have them run diagnostics; the battery may be defective even if the health percentage looks normal.

Does AppleCare+ cover battery replacement?

Yes. AppleCare+ covers battery replacement at no cost if your maximum capacity drops below 80 percent, and it extends coverage to two years from the date you purchased your phone. Without AppleCare+, the standard one-year warranty covers battery replacement only if capacity falls below 80 percent during that first year. After the warranty expires, you pay the full replacement cost.