Replace your iPhone battery when it no longer holds a full day of normal use, when it drains faster than it did a month ago, or when the phone shuts down at 20 percent charge even though the battery reports higher capacity.

Most iPhones lose noticeable battery capacity after 500 full charge cycles — roughly two years of daily use. Apple designs batteries to retain 80 percent of their original capacity at that point. Once you drop below 80 percent capacity, the battery degrades faster. You do not have to wait for complete failure; replacing the battery when it reaches 70 to 75 percent capacity often costs less than waiting for the phone to become unreliable.

The most practical signal is daily behavior: if you charge your phone twice a day when you used to charge it once, or if you carry a power bank that you did not need before, the battery is probably ready to replace. Unexpected shutdowns — the phone powering off at 20 or 30 percent charge — are another clear sign that the battery's internal resistance has risen too high.

Key Takeaways

  • iPhones typically need battery replacement between two and three years of daily use, when capacity drops below 80 percent.
  • You can check your battery's current capacity in Settings > Battery > Battery Health & Charging on iOS 16 and later, or Settings > Battery > Battery Health on earlier versions.
  • Unexpected shutdowns at 20 to 40 percent charge, rapid drain during light use, or needing to charge twice daily are signs the battery should be replaced soon.
  • Apple and authorized repair shops charge between $69 and $99 for battery replacement depending on your iPhone model; third-party shops often charge less but may void your warranty.

How to Check Your Battery's Current Health

Open Settings, then tap Battery, then Battery Health & Charging (on iOS 16 and later) or Battery Health (on iOS 15 and earlier). You will see a percentage labeled "Maximum Capacity." This number tells you how much charge your battery can hold compared to when it was new. A reading of 80 percent or higher means the battery still has useful life. Below 80 percent, degradation accelerates.

The same screen shows "Condition" — either "Normal" or "Service Recommended." If it says "Service Recommended," Apple's system has detected that the battery no longer performs within spec. This does not mean the phone is unsafe; it means the battery should be replaced soon to restore normal performance. If the condition reads "Poor" or "Replace Now," the battery has degraded significantly and replacement is urgent.

Signs Your Battery Needs Replacement Now

An iPhone that shuts down unexpectedly at 20 to 40 percent charge needs a new battery. This happens because the battery's internal resistance has risen so high that it cannot deliver the current the phone demands, even though chemical energy remains. The phone protects itself by powering off. Restarting the phone usually works — the battery voltage recovers slightly — but this cycle repeats and worsens.

Rapid drain during light use is another sign. If your phone loses 15 to 20 percent charge in an hour of texting or browsing, and the Battery Health screen shows capacity below 75 percent, replacement will restore normal runtime. Swelling is rare but serious: if the back of your phone feels warm, the screen has lifted slightly, or the case no longer fits properly, stop using the phone and replace the battery when ready. A swollen battery can damage other components or pose a safety risk.

When to Replace Before Capacity Drops Too Low

You do not have to wait until your battery fails. If you plan to keep your iPhone for three or more years, replacing the battery at 75 to 80 percent capacity — usually around the two-year mark — costs less than waiting for the phone to become unreliable. A battery replacement at 80 percent capacity restores the phone to near-new performance and extends its useful life by another two years.

If you use your phone heavily — streaming, gaming, or navigation for several hours daily — the battery will degrade faster than the two-year average. You may see capacity drop to 75 percent in 18 months. In that case, replacing the battery earlier makes sense because you are already carrying a power bank or charging twice daily.

Cost and Where to Replace

Apple charges $69 for iPhone 15, $79 for iPhone 14 and earlier standard models, and $99 for iPhone Pro models. Authorized Apple retailers and some carrier stores charge the same price. Turnaround is usually one to three business days if you make an appointment; walk-in service may take longer. AppleCare+ covers one battery replacement for free if the capacity has dropped below 80 percent, though you still pay the service fee if you do not have AppleCare+.

Third-party repair shops often charge $40 to $60 for the same service. They are faster — sometimes same-day — but using a non-Apple battery may void your warranty on other repairs. If your phone is still under warranty or you have AppleCare+, use Apple or an authorized retailer. If your phone is out of warranty and you want to save money, a reputable third-party shop is a reasonable choice if they use quality batteries and offer a warranty on their work.

What Happens If You Wait Too Long

Waiting until the battery fails completely does not damage the phone, but it makes the phone unreliable during the replacement process. If your battery shuts the phone down unexpectedly, you cannot back up your data or transfer settings to a new phone without a power source. You also lose the ability to use the phone for calls or navigation if the battery dies at an inconvenient time.

Extremely degraded batteries — below 50 percent capacity — can also cause the phone to throttle its processor to prevent shutdowns. This makes the phone noticeably slower. Replacing the battery restores full speed. If you are considering whether to replace the battery or buy a new phone, check the capacity first: if it is above 60 percent and the phone otherwise works well, battery replacement is usually the better choice.

Battery Lifespan Across iPhone Models

Newer iPhones (iPhone 14 and later) have slightly larger batteries and more efficient processors, so they may reach two and a half to three years before dropping below 80 percent capacity. Older models (iPhone 12 and earlier) typically hit that threshold around two years. The difference is small — usually a few months — and depends more on your charging habits than the model.

Charging habits matter more than age. If you keep your phone plugged in overnight every night, the battery degrades faster than if you charge to 80 percent and unplug. If you let the battery drain to zero regularly, it also degrades faster. Keeping your phone between 20 and 80 percent charge extends battery life, but for most people, normal use and replacement at the two-year mark is the practical approach.

Frequently Asked Questions

Can I replace my iPhone battery myself?

iPhones are glued shut and require special tools to open safely. Self-replacement risks damaging the screen, logic board, or battery itself. Unless you have experience with phone repair, professional replacement is safer and costs only slightly more than the parts alone. Apple and authorized shops warranty their work; self-repair does not.

Does replacing the battery affect my data or settings?

No. Battery replacement does not touch the storage or logic board where your data lives. Your photos, messages, apps, and settings remain unchanged. The technician removes the old battery and installs a new one; the phone boots up exactly as it was.

What if my iPhone is still under warranty?

Apple's standard one-year warranty covers battery replacement only if capacity has dropped below 50 percent due to a defect. If your battery is degraded from normal use, you pay the service fee. AppleCare+ covers one battery replacement at no cost if capacity is below 80 percent, so check whether you have it before paying.

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

If your phone is two to four years old and otherwise works well, battery replacement costs $70 to $100 and extends the phone's life another two years. A new phone costs $800 to $1,200. Replace the battery unless the phone has other hardware problems or you want a newer model for its features.

How long does a battery replacement take?

At Apple or an authorized retailer, expect one to three business days if you book an appointment. Walk-in service may take longer depending on queue. Third-party shops often complete the work same-day. If you need your phone urgently, call ahead to confirm turnaround before you drop it off.