Used iPhone Battery Health: What the Percentage Really Means

Battery health is the one number on a used iPhone that means the same thing on every phone. A scratch is a judgment call. A percentage read off the phone is not. That makes it worth knowing exactly what the number measures, what it leaves out, and how much weight to give it when you are buying.

Everything below about how iOS reports the battery comes from Apple's own support pages, linked as we go.

Where to find battery health

The path depends on the model. Apple's iPhone User Guide gives both:

• iPhone 15 or later: Settings > Battery > Battery Health.
• iPhone 14 or earlier: Settings > Battery > Battery Health & Charging.

On iPhone 15 models and later with iOS 17.4 or later, Apple's battery and performance page for iPhone 11 and later says that screen also shows whether a battery replacement is recommended, the cycle count, when the battery was manufactured and when it was first used.

What Maximum Capacity measures

Maximum Capacity is, in Apple's words on its battery and performance page, "the measure of battery capacity relative to when it was new". A battery at 100 percent holds what it held out of the box. A battery at 85 percent holds 85 percent of that, so a full charge gives you less time than it did new.

What it does not tell you is just as useful to know:

• How hard the phone is used. Two phones at the same percentage last different amounts of time in different hands. Screen brightness, signal and apps all count.
• Whether the battery is original. A replaced battery can read high because it is new. The Parts and Service History section, covered below, tells you.
• Everything else about the phone. A strong battery in a phone with a failing camera is still a phone with a failing camera.

The 80 percent line Apple designs to

Apple publishes a design target, and it makes a sensible yardstick for a used phone:

Both targets are "under ideal conditions", and Apple adds that the exact percentage on any phone depends on how it is regularly used and charged.

A charge cycle is not one trip to the charger. Apple defines it as using an amount equal to 100 percent of the battery's capacity, so using half the battery one day and half the next is one cycle.

What "Service" and the other messages mean

The Battery Health screen can show a few messages, and each one tells you something specific.

• Service next to Battery Health. Apple's page on battery drain says to consider replacing the battery to restore full performance and capacity.
• "Your battery's health is significantly degraded." Apple says this does not indicate a safety issue and you can keep using the battery, but you might see more noticeable battery and performance issues. An Apple Authorized Service Provider can replace it.
• Performance management applied. This appears after an unexpected shutdown when the battery could not deliver the peak power the phone asked for. iOS then manages performance to stop it happening again. On iPhone 11 and later, Apple describes the effects of an aged battery as things like longer app launch times, lower frame rates, backlight dimming or lower speaker volume.
• "Unable to verify this iPhone has a genuine Apple battery." The battery could not be verified, and Apple warns the health figures on the screen may not be accurate.

Replaced batteries and the Unknown label

A replaced battery is not a problem in itself. A good replacement can be better than a tired original. What matters is whether you can trust the reading.

Apple's preowned iPhone page says battery health information is not available for unknown or nongenuine batteries. Check Settings > General > About for a Parts and Service History section. Apple's Parts and Service History page explains the labels: Genuine means a genuine Apple part and process, and Unknown can mean a nongenuine part, a part not working as expected, or one that could not be verified. With an Unknown battery, the percentage you were going to rely on may simply not be there.

So what counts as good on a used phone?

There is no single cutoff that fits every buyer, and we would rather not invent one. These are the questions that actually decide it.

1. Where is it against Apple's 80 percent design line? That is the capacity Apple designs its batteries to keep after 500 or 1,000 complete cycles. A reading above it has not reached that benchmark yet, and one below it has passed it.
2. On an iPhone 15 or later, what is the cycle count? The same percentage reads differently on a phone with few cycles and one with many. Read the two together.
3. Is there a message? With Service or "significantly degraded" showing, Apple suggests considering a replacement, whatever the percentage says.
4. Is it genuine? An Unknown battery or an "Unable to verify" message means the number is not reliable.
5. How long will you keep it, and how hard will you use it? A light user replacing a phone again soon can accept a lower reading than someone who needs a full day on one charge.

Then price it in. A lower battery reading is a fair reason for a lower price, and a replacement is a known repair, so it should not scare you off a phone that is right in every other way. The used iPhone buying checklist covers everything else to test before you pay.

Battery health when you sell to us

If you are on the other side of the counter, here is how battery health affects a phone you sell to iPhones.LA. A battery at 79 percent health or below is a flat $20 off, whatever the grade. It never changes the grade itself, and that is the only way the battery enters the offer. A clean phone with a worn battery is still a clean phone.

That makes the replace-before-selling question simple: if the battery is at 79 percent or below and a new one would cost you more than $20, sell the phone as it is. Our grades are here:

A battery at 79% health or below is a flat $20 off at any grade. It does not change the grade.

To see what your phone is worth, try the value pages for the iPhone 13 or iPhone 12, or get an instant cash offer at /sell. The guide to selling an iPhone in Los Angeles and the prep checklist cover the rest.

Battery health on every phone we sell

When you buy from our shop, you do not have to take a seller's word for the battery. Every device is hand-tested, its IMEI is verified clean, and its real battery health is shown on the listing, so you can compare phones on the number that matters to you before you buy. Checkout is processed securely by Stripe, with free pickup in Long Beach, local delivery by zone, or shipping anywhere in the US. What we check and our policies are at /shop#details.

Frequently asked questions

What is a good battery health for a used iPhone?

Apple designs iPhone batteries to keep 80 percent of their original capacity at 500 complete cycles (iPhone 14 and earlier) or 1,000 cycles (iPhone 15 and later). Judge a used battery against that line, its cycle count where shown, and any Service message.

What does Service mean on iPhone battery health?

Apple says that if you see Service next to Battery Health, you should consider replacing the battery to restore full performance and capacity. Apple also says the related "significantly degraded" message does not indicate a safety issue.

Where do I find the battery cycle count on an iPhone?

On iPhone 15 models and later with iOS 17.4 or later, go to Settings > Battery > Battery Health. Apple does not show cycle count on that screen for earlier models.

Does battery health affect how much my iPhone is worth?

When you sell to iPhones.LA, a battery at 79 percent health or below is a flat $20 off whatever the grade. It does not lower the grade itself.

Why does my used iPhone say it cannot verify the battery?

The "Unable to verify this iPhone has a genuine Apple battery" message means iOS could not verify the battery, which can happen after a battery replacement. Apple warns the battery health details on that screen may not be accurate.