Replace your iPhone battery when it drops below 80 percent maximum capacity, or sooner if you notice rapid drain during normal use

Your iPhone battery degrades over time—this is normal chemistry, not a defect. Apple designs iPhone batteries to retain 80 percent of their original capacity after 500 full charge cycles. Once your battery falls below that threshold, you will notice the phone drains faster, shuts down unexpectedly at low percentages, or struggles to run demanding apps. You do not have to wait until the battery is completely dead to replace it. The right time depends on how much the degradation bothers you and how you use your phone.

You can check your battery's current health in Settings. Open Settings, tap Battery, then Battery Health & Charging. The number shown under "Maximum Capacity" tells you what percentage of the battery's original charge it can still hold. If it reads 79 percent or lower, Apple will perform a replacement. If it reads 80 percent or higher but you are experiencing problems, the issue may be software-related rather than battery age.

Key Takeaways

  • Check your battery health in Settings under Battery > Battery Health & Charging to see the current maximum capacity percentage.
  • Apple will replace your battery if maximum capacity is 79 percent or lower, or if the battery is still under warranty and showing defects.
  • You can replace the battery before it reaches 80 percent if rapid drain or unexpected shutdowns are affecting your daily use.
  • Battery replacement costs vary by iPhone model and whether you use Apple or a third-party repair shop, so compare prices before choosing.
  • Keeping your phone cool, avoiding extreme temperatures, and not letting the battery drain completely regularly will slow degradation.

What the Battery Health percentage actually means

The maximum capacity number in Battery Health is not the same as your current charge level. If your battery shows 75 percent maximum capacity, that means the battery can now hold only 75 percent of the charge it held when the phone was new. A full charge today gives you less runtime than a full charge did a year ago.

This percentage drops gradually over time and use. A phone used heavily for two years might show 70 percent capacity. A phone used lightly might still show 85 percent after the same time. The rate depends on how often you charge, whether you let it drain to zero, how hot the phone gets during use, and whether you use fast charging frequently.

Once capacity drops below 80 percent, Apple considers the battery degraded enough to warrant replacement under their standard service. This does not mean the battery will stop working—it means it no longer meets Apple's performance standard for a new device.

When to replace before reaching 80 percent

You do not have to wait until the battery hits 79 percent to replace it. If your phone is shutting down unexpectedly when the battery shows 20 or 30 percent remaining, or if it drains from 50 percent to dead in an hour of normal use, the battery is affecting your ability to use the phone. In that case, replacement makes sense even if the health percentage is still above 80.

Unexpected shutdowns happen when the battery cannot deliver the power the phone needs, even though it still holds a charge. This is more common in cold weather or when running multiple apps at once. If you notice this pattern, go to Settings > Battery > Battery Health & Charging and note the maximum capacity. If it is below 80 percent, Apple will replace it. If it is 80 percent or higher, the shutdowns may be caused by a software issue, and you should restart the phone or check for pending software updates first.

Apple battery replacement versus third-party repair

Apple replaces batteries at their retail stores and through their mail-in repair service. The cost depends on your iPhone model and whether the phone is under warranty. Out-of-warranty battery replacements typically cost between $50 and $70 for current models, though older models may cost more. If your phone is under AppleCare+, battery replacement is usually covered at no cost.

Third-party repair shops—including Best Buy's Geek Squad and independent local repair stores—also replace iPhone batteries, often for less money. Prices vary widely by location and shop. The trade-off is that third-party repairs do not carry Apple's warranty on the battery itself, and some shops may use non-original parts. If you choose a third-party shop, ask whether they use original Apple batteries or aftermarket batteries, and what warranty they offer on the replacement.

Mail-in repair through Apple takes 5 to 7 business days plus shipping time. In-store replacement at an Apple Store usually takes the same day if you make an appointment and arrive early, though wait times vary by location. Third-party shops often complete the work while you wait, sometimes in under an hour.

How to slow battery degradation before replacement

While battery degradation is inevitable, you can slow it down by changing a few habits. Keep your phone out of extreme heat—do not leave it in a hot car or in direct sunlight for long periods. Heat is the biggest enemy of lithium batteries. If your phone feels warm during charging, move it to a cooler location or remove any thick case while charging.

Avoid letting the battery drain completely to zero regularly. Charging from 20 percent to 80 percent, rather than 0 to 100 percent, puts less stress on the battery chemistry. If your phone supports Optimized Battery Charging, turn it on in Settings > Battery > Battery Health & Charging. This feature learns your charging patterns and slows charging to 80 percent overnight, then finishes the last 20 percent before you wake up. It reduces the time the battery spends at 100 percent, which slows degradation.

Disable fast charging if you do not need it. Fast charging generates more heat and stresses the battery more than standard charging. Use a standard charger for overnight charging and reserve fast charging for times when you genuinely need the phone charged quickly.

What happens if you ignore a degraded battery

If you continue using an iPhone with a battery below 80 percent maximum capacity, the phone will work, but the experience will degrade. You will need to charge more often. The phone may shut down unexpectedly when you need it, especially in cold weather or during demanding tasks. Over months, the battery may swell slightly, which can push the screen or back panel out of alignment—this is rare but possible.

The phone itself will not be damaged by a degraded battery, but your ability to rely on it will suffer. If you travel, work away from a charger, or use your phone for navigation or communication, a degraded battery becomes a real problem. In those cases, replacement is worth doing sooner rather than later, even if the capacity is still above 80 percent.

Frequently Asked Questions

Does Apple replace the battery for free if it is below 80 percent?

Not automatically. If your phone is under warranty or covered by AppleCare+, battery replacement is free. If your phone is out of warranty, Apple charges a service fee—typically $50 to $70 depending on the model. Check your warranty status in Settings > General > About, or ask at an Apple Store.

Can I replace the battery myself?

iPhones are not designed for user battery replacement. The battery is glued in, and opening the phone requires specialized tools and risks damaging the screen, water seals, or internal components. Unless you have experience with phone repair, professional replacement is safer and often cheaper than the cost of fixing accidental damage.

Will my phone be slower if the battery is degraded?

Your phone may feel slower if the battery is very degraded and the phone is throttling performance to prevent unexpected shutdowns. This is Apple's way of keeping the phone stable when the battery cannot deliver peak power. Replacing the battery usually restores the original speed.

How long does a new iPhone battery last before it needs replacement?

Most iPhone batteries reach 80 percent capacity after 2 to 3 years of typical use. Heavy users may see that drop in 18 months. Light users might stay above 80 percent for 4 years. The exact timeline depends on how often you charge, your usage patterns, and environmental conditions.

Should I replace the battery or buy a new phone?

If your phone is 3 to 5 years old and the only issue is battery capacity, replacement is usually worth it. A new battery costs $50 to $70 and restores the phone to reliable daily use. A new phone costs hundreds of dollars. If the phone has other problems—cracked screen, water damage, or very old software—then a new phone may make more sense.