Battery health is Apple's measure of how much charge your iPhone's battery holds compared with when it was new, shown in Settings › Battery › Battery Health. Buyers pay attention to 80% because Apple uses it as its design reference point for a healthy battery. A phone below 80%, or one showing a Service message, is still sellable: the battery changes the quote, not whether the phone is bought.
This guide explains where the number comes from, what Apple actually says about it, whether a new battery is worth fitting before you sell, and how to answer the battery question honestly. If you already know your figure and want a quote, sell your iPhone through our form.
Where do you find battery health on an iPhone?
Open Settings, tap Battery, then Battery Health. The figure that matters is Maximum Capacity, a percentage of the battery's original capacity. The same screen tells you whether the battery supports normal peak performance, or whether Apple recommends a service.
On the iPhone 15 and later, Apple also shows the battery's cycle count, its manufacture date and the date of first use, as described in Apple's guide to understanding iPhone battery usage and health. That covers every iPhone we buy, from the iPhone 15 to the iPhone 17 family.
What does the percentage actually mean?
Maximum Capacity is not how full the battery is today; it is how big the battery's tank still is. A phone at 88% holds roughly 88% of the charge it held when new, so a full charge lasts correspondingly less time.
Apple publishes design figures for how batteries age in its article on iPhone battery and performance:
| Model | Apple's design statement |
|---|---|
| iPhone 14 and earlier | Designed to retain 80 percent of original capacity at 500 complete charge cycles, under ideal conditions |
| iPhone 15 range | Designed to retain 80 percent of original capacity at 1000 complete charge cycles, under ideal conditions |
Two phrases in those statements matter. "Complete charge cycles" means using a full battery's worth of charge, which can be spread across several days. And "under ideal conditions" means real phones vary: heat, fast charging habits and leaving a phone at 100% for long periods all age a battery faster.
Why is 80% the number buyers watch?
Because it is the line Apple itself draws. Apple designs batteries around keeping 80% capacity for a set number of cycles, and AppleCare+ covers a battery replacement when capacity drops below 80%. When a battery is significantly degraded, Apple shows a message recommending service and notes that this does not indicate a safety issue.
So a buyer reads the number in bands. Above 90%, the battery is close to new. Between 80% and 89%, it is ordinary wear for a phone that has been used every day. Under 80%, or with a Service message, the next owner will probably want a new battery, and a quote reflects that.
How does our form treat battery health?
Our form asks you to pick a band rather than type a figure, which keeps things simple:
| Your Battery Health screen shows | Choose in the form |
|---|---|
| Maximum Capacity 90% or higher | 90 to 100% |
| Maximum Capacity 80% to 89% | 80 to 89% |
| Under 80%, or a Service message | Under 80% or Service |
| You cannot check (for example, the phone will not turn on) | Not sure |
If the battery also runs flat unusually fast or the phone shuts down unexpectedly, tick Battery won't hold charge under "Anything not working?" as well. Battery health is one of several answers a person reads when pricing your iPhone by hand, alongside the model, storage, screen and body condition, so a lower band does not decide the quote on its own.
Should you replace the battery before selling?
Usually not before you have a quote. The logic is simple arithmetic, done in this order:
- Get a quote for the phone as it is, with the honest battery band.
- Find the replacement cost. Apple lists its own battery service prices on its iPhone repair page, where you choose your model.
- Ask whether a new battery would move your phone up a band, and whether that is worth more than the replacement costs you.
If the repair costs more than it adds, sell the phone as it is. The next owner can have the battery replaced, and you save the trip.
There is one clear exception. If your iPhone is covered by AppleCare+ and its capacity has dropped below 80%, Apple states that it will replace the battery at no extra charge. You can check your coverage at checkcoverage.apple.com. A free battery before you sell is an easy win.
What about a cheaper third-party battery?
Be careful. iPhones record replaced parts under Settings › General › About › Parts and Service History, and a battery that is not a genuine Apple part is listed there. A buyer will see it at inspection. If your phone has already had a non-Apple battery fitted, say so in the message box rather than letting it be found.
How do you protect battery health until you sell?
If you are keeping the phone for a few more months, a few habits slow the decline:
- Keep it cool. Heat is the biggest single enemy of lithium-ion batteries. Do not leave the phone on a car dashboard or charging under a pillow.
- Use the charging options in Battery settings. The iPhone 15 and later let you limit charging below 100%, which reduces the time the battery spends full.
- Leave Optimised Battery Charging on, so the phone learns your routine and finishes charging just before you usually unplug it.
None of these will reverse wear that has already happened, so if you have already upgraded, the phone in the drawer is not getting any better. Our guide on when to sell your iPhone before you upgrade covers the timing.
What if the battery is swollen or the phone will not charge?
Stop charging it. A swollen battery can push the screen away from the frame, which you will see as a gap along one edge. Choose No power at all if it will not start, tick Battery won't hold charge, and describe what you can see. Our page on selling a broken or cracked iPhone explains how faulty phones are quoted and how to remove a dead phone from your Apple Account at iCloud.com, since it cannot be signed out on the handset.
The short version
Check Settings › Battery › Battery Health, choose the matching band, and do not pay for a battery before you know what it would add. If you have AppleCare+ and the phone is under 80%, get the free replacement first. Either way, prepare the phone properly before it leaves you: our iPhone selling checklist covers signing out, erasing and moving your eSIM in the right order.
Good to know
Quick answers
Everything sellers ask us before posting their Mac - answered straight.
Where do I find battery health on my iPhone?
Open Settings, tap Battery, then Battery Health. The Maximum Capacity figure is the battery's capacity compared with when it was new. On the iPhone 15 and later, Apple also shows the cycle count, the manufacture date and the date of first use, which buyers find useful.
Can I still sell an iPhone with battery health under 80%?
Yes. A worn battery changes the quote, not whether the phone is bought. In our form choose Under 80% or Service, and tick Battery won't hold charge as well if it runs flat quickly. Describing it honestly is what keeps the quote fixed when the phone is inspected.
Should I replace my iPhone battery before selling it?
Only if the replacement costs less than it adds to the price, so get a quote for the phone as it is first. If you have AppleCare+ and the capacity has dropped below 80%, Apple says it replaces the battery at no extra charge, which is worth doing before you sell.