How to check your iPhone's battery health (and what the number means)

Battery health tells you how much of its original capacity a battery can still hold. It's the first thing we test on every phone we sell, and it's the number you should check before buying any used iPhone.

Where to find it

On any iPhone:

• Open Settings → Battery → Battery Health & Charging
• Read the Maximum Capacity percentage
• Check that Peak Performance Capability says the battery supports normal performance

What's a healthy number?

A brand-new battery reads 100%. Apple designs iPhone batteries to keep up to 80% of their capacity through around 500 full charge cycles — for most people, a couple of years of use.

As a rough guide:

• 90%+ — excellent
• 85–89% — very good
• 80–84% — fine for everyday use
• below 80% — you'll notice shorter screen time; consider a replacement soon

A few tips

• A lower percentage isn't a dealbreaker — it just should be reflected in the price.
• iOS shows a Service message when a battery is significantly degraded; ask the seller if you see it.
• A fresh battery replacement resets capacity to 100%, so ask whether the battery is original or replaced.

Every iPhone at PhoneBase lists its measured battery health up front, so you know exactly what you're getting before you buy.