Replace your iPhone battery when it no longer holds a charge through a normal day, when the phone shuts down unexpectedly at 20–30% battery, or when the battery health drops below 80%

Your iPhone battery degrades with every charge cycle. After about 500 full charge cycles, most iPhone batteries retain roughly 80% of their original capacity. You do not have to wait until the battery is completely dead to replace it—in fact, waiting that long usually means you've already lost significant usable time on your phone.

The most practical signal is daily life: if you're charging your phone twice a day when you used to charge it once, or if you're carrying a power bank because the battery no longer lasts through your workday, replacement makes sense. Unexpected shutdowns—where the phone powers off even though the battery percentage shows 20% or higher—are another clear sign that the battery chemistry has degraded enough to affect performance.

Key Takeaways

  • Check your battery health percentage in Settings > Battery > Battery Health & Charging; anything below 80% means the battery has lost significant capacity.
  • Unexpected shutdowns at mid-range battery percentages indicate the battery can no longer deliver the power your phone needs, even if the percentage looks fine.
  • If you're charging more than once per day or the phone feels slower under load, battery replacement usually restores both runtime and performance.
  • Apple and authorized repair shops replace batteries for a fixed fee; third-party repairs are cheaper but may affect water resistance and warranty coverage.
  • Replacing the battery is almost always cheaper than replacing the phone, even for older models.

How to check your iPhone battery health right now

Open Settings, tap Battery, then tap Battery Health & Charging. You will see a percentage labeled "Maximum Capacity"—this is the most useful number on your phone for deciding whether to replace the battery. A reading of 100% means the battery is new or nearly new. At 80%, the battery has completed roughly 500 charge cycles and has lost about one-fifth of its original capacity. Below 80%, you're losing noticeable runtime with each passing month.

You will also see a "Battery Condition" line that says either "Normal" or "Service Recommended." If it says "Service Recommended," Apple is telling you the battery has degraded enough that replacement would improve your phone's behavior. This is not a warning that your phone will break—it means the battery is no longer performing as designed.

Unexpected shutdowns mean the battery cannot deliver power anymore

If your iPhone powers off when the battery percentage shows 20%, 30%, or even 50%, the battery is failing. This happens because the battery's internal resistance has increased so much that it cannot supply the current your phone needs during demanding tasks like photography, video, or gaming. The phone shuts down to protect itself, even though the battery still has chemical energy left.

This is not a software problem and restarting will not fix it. The phone will power back on once you plug it in, because charging reduces the internal resistance temporarily. But the shutdowns will keep happening until you replace the battery. If you're experiencing this, replacement should be your next step.

Battery replacement costs and where to get it done

Apple charges a flat fee for battery replacement at an Apple Store or Apple Authorized Service Provider. The cost varies by iPhone model—older models are usually cheaper than the newest ones—but generally ranges from around $50 to $70. You can check the exact price for your model by visiting apple.com/support, selecting your phone, and looking for battery service.

Authorized Service Providers (independent repair shops certified by Apple) charge the same Apple-set price and use genuine Apple batteries. Third-party repair shops often charge less, sometimes $20 to $40 less, but they may use non-genuine batteries and the repair may void any remaining warranty. Third-party replacement can also affect your phone's water resistance rating, since opening the phone requires breaking the water-resistant seal.

Turnaround time at Apple Stores is usually same-day or next-day if you have an appointment. Mail-in service through Apple takes about a week. Independent shops often have faster turnaround but availability varies by location.

When to replace the battery before it fails completely

You do not have to wait for unexpected shutdowns or a battery health reading below 50% to replace the battery. Many people replace it at 80–85% maximum capacity, before the degradation becomes annoying in daily use. This is a reasonable choice if you plan to keep the phone for another two or three years.

If you use your phone heavily—constant video calls, gaming, or outdoor work—the battery will degrade faster and you may want to replace it sooner. If you use it lightly and mostly keep it plugged in, you can wait longer. The decision is yours based on how much the reduced runtime bothers you.

Battery replacement versus buying a new phone

A battery replacement costs $50 to $70. A new iPhone costs $800 to $1,600. Even if your phone is three or four years old, replacing the battery is almost always the cheaper option and will restore the phone to near-original performance. The only reason to replace the phone instead is if the battery is the last thing wrong with it—if the screen is cracked, the camera is broken, or the phone has other hardware damage that would cost more to fix.

If your phone is still receiving iOS updates and you like how it works otherwise, battery replacement extends its useful life by years. If the phone is so old that Apple has stopped supporting it with updates, you have a longer timeline to decide, but the battery will still degrade and replacement will still help.

What happens to your phone after battery replacement

After replacement, your iPhone will show 100% maximum capacity again and the "Battery Condition" line will read "Normal." The phone will no longer shut down unexpectedly. Runtime will return to what it was when the phone was new, or close to it. If the phone felt slower under load before replacement, it will feel faster, because the phone no longer needs to throttle performance to protect itself from power delivery failures.

The replaced battery will degrade at the same rate as the original—roughly 1% per 100 charge cycles. You will not need another replacement for several years unless you charge the phone multiple times per day every single day.

Frequently Asked Questions

Does Apple replace batteries while I wait?

At most Apple Stores, battery replacement is same-day if you have an appointment and arrive early in the day. If the store is busy or you walk in without an appointment, you may have to leave the phone and pick it up the next day. Mail-in service takes about a week. Call your local Apple Store to ask about wait times before you go.

Will replacing the battery void my warranty?

No. Apple's warranty covers battery replacement as a repair, not as a voiding event. If you use an Apple Store or Authorized Service Provider, the replacement itself is covered under Apple's standard service terms. Third-party repairs may affect your warranty coverage depending on what else they do to the phone.

Can I replace the battery myself?

iPhones are glued together and require special tools to open safely without damaging the screen or internal components. Self-replacement is possible but difficult and risks breaking the phone. Unless you have experience with phone repair, professional replacement is worth the cost.

What if my phone is still under AppleCare+?

AppleCare+ covers battery replacement at no cost if the battery health has dropped below 80%. If your phone is still covered, battery service is free. Check your coverage status in Settings > General > About, or ask at an Apple Store.

Does cold weather affect when I should replace the battery?

Cold weather makes any battery perform worse temporarily—your phone may shut down in freezing temperatures even with 40% battery remaining. This is normal and the phone will work again once it warms up. However, if your phone shuts down unexpectedly in normal room temperature, the battery needs replacement regardless of weather.