iPhone Battery Health Check

Find Your Maximum Capacity

1. Open the Settings app.
2. Scroll down and tap Battery.
3. Tap Battery Health & Charging (on iPhone 15 and later it is simply Battery Health).
4. Read Maximum Capacity — the percentage of the original capacity the battery still holds.

This screen requires iOS 11.3 or later. On an iPhone 6 or newer running an older version, update iOS first.

Find Your Cycle Count

iOS 17 and later exposes the cycle count directly, which earlier versions never did:

1. Open Settings → General → About.
2. Scroll down to Cycle Count.

On iPhone 15 and later, manufacture date and first use date appear on the same screen — genuinely useful when checking whether a seller's account of a phone's age holds up.

What the Numbers Mean

• 90 percent and above — effectively like new.
• 85 to 89 percent — normal for a phone one to two years old.
• 80 to 84 percent — noticeably shorter runtime; plan for a replacement.
• Below 80 percent — Apple considers the battery consumed and iOS shows a Service message.

On cycle count: iPhone 14 and later are rated for 1000 cycles while retaining 80 percent capacity — Apple extended that rating to the iPhone 14 family in 2024, having originally quoted 500. iPhone 13 and earlier remain rated for 500. A cycle is one full battery's worth of use, not one plug-in.

Peak Performance Capability

Below Maximum Capacity, iOS reports whether performance management is active. When a battery can no longer deliver peak current, iOS deliberately slows the processor to prevent unexpected shutdowns. If the message says performance management has been applied, a battery replacement restores full speed — the phone itself is not worn out.

The "Unknown Part" Battery Warning

If you see Unknown Part, or a message that iOS cannot verify the battery is genuine, the phone has a third-party or transplanted battery. On many affected devices the Maximum Capacity figure disappears altogether.

When buying used this is a double signal: you lose the health reading you most wanted to check, and you learn the phone has been opened before. That is not automatically disqualifying — a professionally replaced battery can be perfectly good — but ask who did the work and what else was replaced. A screen or camera swapped at the same time will often show its own "Unknown Part" notice under Settings → General → About → Parts and Service History.

Free Replacement Under Warranty or AppleCare+

If Maximum Capacity is below 80 percent while the iPhone is still covered by warranty or AppleCare+, Apple replaces the battery at no charge. Check coverage by serial number (Settings → General → About) on Apple's Check Coverage page, and book the replacement before the coverage lapses.

Buying a Used iPhone?

Check the battery on the device itself — never from a screenshot, which is trivially edited. Aim for 85 percent or higher; treat anything under 80 percent as roughly the price of a replacement off your offer.

Two checks matter even more than the battery, because they decide whether the phone is usable at all: confirm Find My iPhone is switched off and the device has been signed out of the seller's Apple ID, or it will be activation-locked and unusable to you. Our used iPhone checklist covers both, plus the screen, touch, cameras, microphone and sensors.

Slowing Down Battery Wear

• Leave Optimised Battery Charging on. It holds the phone at 80 percent overnight and finishes charging just before you normally wake up.
• Use the 80 percent charge limit (iPhone 15 and later) if you mostly top up at a desk.
• Keep it cool. Heat degrades lithium-ion faster than cycles do — avoid charging under a pillow or leaving the phone on a car dashboard.
• Lower screen brightness and reduce the refresh rate on ProMotion models; the display is the biggest single drain.
• Avoid regular full drains to zero. Staying roughly between 20 and 80 percent is easier on the cells than deep cycling.

Checking a Non-Apple Device?

The live browser readout on our battery test works on Android, Windows and ChromeOS in Chrome, Edge and Opera. For laptops specifically, see the Windows battery report guide or MacBook battery health.

Frequently Asked Questions