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Phone Battery Health: What the Number Means and When to Worry

Your iPhone’s Battery Health screen compares today’s capacity with when it was new. Here’s how to read it, what Apple says to expect, and habits that slow the decline.

By SHOP & SPOT EditorsLast reviewed Nov 9, 2026Research-based guide · 2 sources

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A person holding a smartphone showing a low battery.

Photo: Alexander Andrews on Unsplash

This guide is for iPhone owners who saw a battery health percentage drop and want to know whether it’s time for a new battery or a new phone.

Every rechargeable battery slowly holds less charge as it ages. The Battery Health screen on an iPhone puts a number on that, which helps you decide whether a battery replacement, not a new phone, would fix your problem.

Where to find it

Apple’s path: open Settings, tap Battery, then tap Battery Health.1 Menu names can shift slightly between iOS versions.

What “Maximum Capacity” means

Apple says maximum battery capacity measures the battery’s capacity relative to when it was new.1 A reading of 85% means the battery now holds about 85% of the charge it held out of the box, so a full charge lasts less time.

What Apple says to expect

Model Apple’s design target1
iPhone 14 and earlier Retain 80% of original capacity at 500 complete charge cycles
iPhone 15 models Retain 80% of original capacity at 1,000 complete charge cycles

A charge cycle is a full 100% worth of charging, which can add up over several partial charges. These are design targets, not guarantees for any one phone.

Habits that help

  • Avoid heat. Apple advises against charging or leaving your iPhone in hot environments, including direct sun, for long periods.1
  • Use the charging settings. Apple says Optimized Battery Charging is designed to reduce battery wear by delaying charging past 80% in certain situations.2 On iPhone 15 and later, you can also set a Charge Limit between 80% and 100% in 5% steps, under Settings › Battery › Charging.2

Our advice: if you usually end the day with plenty of charge left, an 80% or 85% limit costs you little and may help the battery age more slowly.

Replace the battery or the phone?

Our rule of thumb: if the phone still does everything you need and the main complaint is battery life, a battery replacement is usually the cheaper fix. Get a quote from Apple or an authorized provider and compare it with the trade-in value of the phone. If the phone is also slow for other reasons, too small on storage or no longer getting updates, it may be time to upgrade. Before you trade it in, see our guide on wiping an iPhone before you sell it.

Quick check

  • Settings › Battery › Battery Health.
  • Compare the number with Apple’s 80% design target for your model.
  • Keep the phone out of heat while charging.
  • Turn on Optimized Battery Charging or a Charge Limit.

Sources & method

How we researched this

  • This is a research-based guide, not a hands-on product test.
  • Every measurement and safety figure is attributed to the source it comes from. Where we give our own advice, we say so.
  • We don’t rank or recommend specific products in this guide.

Sources

  1. iPhone battery and performance, Apple. Accessed Nov 9, 2026.
  2. About Charge Limit and Optimized Battery Charging on iPhone, Apple. Accessed Nov 9, 2026.

Review history

  • Published Nov 9, 2026.