What Battery Health Percentage Means on a Used iPhone
A clear explanation of iPhone battery health percentage and how to use it when buying a used phone.
Battery health percentage is one of the most useful numbers available on a used iPhone, but it's often misunderstood. Here's what it's actually measuring and how to use it when buying.
What the percentage is comparing
Battery health, found under Settings > Battery > Battery Health & Charging, compares the battery's current maximum capacity to its capacity when it was brand new. A battery reading 85% can currently hold about 85% of the charge it could hold when new — it isn't a measure of how much charge is currently in the battery, which is the separate percentage shown in the status bar.
What counts as a reasonable number
Above 85% is generally considered good for a used phone and shouldn't cause any noticeable difference in daily use. Between 80% and 85% is acceptable but worth factoring into your offer, since a replacement will likely be needed within a year or two of regular use. Below 80%, expect noticeably shorter battery life day to day, and budget for a replacement sooner rather than later.
Why this number matters more than the phone's age
Battery wear depends heavily on how a phone was actually charged and used, not just how old it is — a two-year-old phone that was charged carefully can have better battery health than a one-year-old phone that was frequently left charging overnight or used heavily in hot conditions. Always check the actual number rather than assuming based on age alone.
Watch for a replaced but non-genuine battery
If a battery has been replaced with a non-genuine part, iOS may show a message under Battery Health noting it can't verify the battery's information, or "Service" may appear as a recommendation even at a seemingly high percentage. This is worth asking the seller about directly, since a non-genuine replacement can behave less predictably than an original part.
How to use this when negotiating
A lower battery health percentage is a fair, specific, and verifiable reason to negotiate the price down — it's not a vague complaint, it's a real cost you'll likely face soon after buying. Ask the seller to show you this number directly during your inspection, alongside the other checks covered in our guide on checking a used iPhone before buying.
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