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How to Calibrate Your iPhone’s Battery

How to Calibrate Your iPhone's Battery

updated by Chad Evans
March 25, 2023 at 4:03 p.m. PST
  • The iPhone features remarkable battery life, however, not every user experiences peak performance.
  • It is essential to calibrate lithium-ion batteries periodically.
  • This article details the process for maintaining your iPhone’s battery, which will ensure more accurate battery metering.
  • This method also applies to the Apple Watch, MacBook, iPad and iPod Touch, as well as most other devices with lithium-ion “smart” batteries.
  • Battery calibration (sometimes called “recalibration”) only requires draining the battery and fully charging it once.
  • Draining and fully charging your iPhone twice decreases its battery’s lifespan.
  • iOS will automatically calibrate batteries for an iPhone 11 (or newer) running iOS 14.5 (or later).

Table of Contents

iPhone 11, 12, 13, 14 Running iOS 14.5 Through 16.3.1 Don’t Require Manual Calibration
Why You Should Still Manually Calibrate Your iPhone
Step By Step Battery Calibration
How To Calibrate Your iPhone’s Battery (Detailed Instructions)
Why Calibrate Your iPhone’s Battery?
iPhone Battery Calibration Myths Debunked
Make Your iPhone’s Battery Last Longer
More Information

iPhone 11, 12, 13, 14 Running iOS 14.5 Through 16.3.1 Don’t Require Manual Calibration

Before you begin the calibration process, it’s essential to know your iPhone’s model number. Newer devices running iOS 14.5 or later do not require manual calibration. These models include the iPhone 11 and later.

Apple’s newest devices and operating systems now include technology to recalibrate battery statistics when necessary. This automated maintenance routine runs without user intervention whenever the battery needs calibration.

iOS Automatically Calibrates Your iPhone's Battery

To check your battery’s status, tap on Settings > Battery > Battery Health. If the recalibration process is running, users see the following:

Your battery health reporting system is recalibrating Maximum Capacity and Peak Performance Capability. This process may take a few weeks. Learn more…

Apple’s recalibration process will also determine if your iPhone’s battery needs replacement. Devices with deteriorating batteries will display this message on the Battery Health screen:

Recalibration of the battery health reporting system was not successful. An Apple Authorized Service Provider can replace the battery free of charge to restore full performance and capacity. More about service options…

Of course, you can still calibrate your iPhone battery by following the steps in this article. I have a brand new iPhone 14 Pro Max, and I calibrated the battery about a week after unboxing. It appears to have extended battery life significantly. Apart from this first-time calibration, I top off my phone as needed, performing calibration only every 1-3 months. I usually do it a few weeks after installing a major iOS update.

Recent research into Apple’s recalibration process seems to show that it doesn’t do anything. Furthermore, Apple’s battery metering in iOS 16 is way off on my iPhone 14 Pro Max and there’s no recalibration process running. This is all the more reason you should still manually calibrate/recalibrate your iPhone. Apple’s recalibration process either doesn’t work or doesn’t kick in, even when battery metering is grossly inaccurate.

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Why You Should Still Manually Calibrate Your iPhone

Although Apple added iOS software to handle battery calibration automatically, the algorithm waits for you to go from 0% to 100% through regular usage. That’s why it sometimes takes days and other times takes weeks.

I have a new iPhone 14 Pro Max, and so far, Apple’s recalibration has yet to kick in. My iPhone 13 Pro Max likewise never required Apple’s recalibration. This is probably because I run my battery down to 0% and charge it to 100% at least once every three months.

Talking to a few people who have experienced the “battery health reporting system is recalibrating Maximum Capacity and Peak Performance Capability” message, they found that draining their iPhone to 0% and charging it to 100% hastened the process. Apple’s recalibration process is nothing new. The iPhone maker just added messaging and better data management around the existing process.

Even if you have the latest iPhone running the most recent version of iOS, it’s still a good idea to manually calibrate (or recalibrate) your iPhone. It prevents Apple’s process from kicking in. If iOS is automatically recalibrating your iPhone, you can help the process along by draining your iPhone to 0% and charging it fully.

The only unnecessary step for a modern iPhone is resetting the device. A soft reset used to be necessary to clear cached data. Apple’s recalibration algorithm seems to clear out this data now, so it’s no longer required.

Unfortunately, it appears as though Apple’s recalibration process may be a ruse. Recently, while researching this article, I tried to drain my iPhone 14 Pro Max with 1% battery charge left. It took 30 minutes to shut off, with the screen at maximum brightness, the flashlight on, and a movie playing. Needless to say, Apple’s automatic recalibration doesn’t work when 1% battery life lasts for 30 minutes.

Some may say it’s a good problem to have. At 1% battery life, I might have 30 minutes of iPhone time left, even with power-draining applications running. Clearly, this is inaccurate.

Given these findings, it appears that Apple’s recalibration process doesn’t really work. It hasn’t kicked in on my iPhone 14 Pro Max, and the battery meter is inaccurate.

I’m still trying to ascertain whether manual calibration solves the issue. If not, Apple’s battery metering is inaccurate, and you’ll just have to accept it.

iPhone 14 Pro Max Lasts 30 Minutes With 1% Battery Level
When my iPhone 14 Pro Max (not even six months old!) was at a 1% battery level, I cranked up the brightness, turned on the flashlight, and played a movie to drain the battery. It took 30 minutes. This is not good. It shows that Apple’s recalibration process doesn’t work and the iPhone’s battery metering is way off.

With the newest iPhone 14 Pro Max, you go from a 100% to 90% battery level in 20 minutes, but 1% to 0% takes 30 minutes. Danger, Will Robinson! This does not compute. It looks like Apple’s recalibration algorithm is more about impressing or placating users than effective battery management. That’s probably why it’s a black box with no feedback or statistics other than the ambiguous “battery health” percentage.

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Step By Step Battery Calibration

Draining and recharging your iPhone will calibrate its battery.

The following process is what I consider to be the gold standard of iPhone battery calibration. For some, it might not be possible to follow all of these steps. If you are an on-call professional or hopelessly addicted to your iPhone, you might not be able to turn off your iPhone overnight or even for a few hours. At the bare minimum, you need to drain the battery until the device shuts off, charge your iPhone to 100%, then do a soft reset to remove cached battery data.

Remember, you only need to do this on an older iPhone. If you have an iPhone XR or older, you need to manually calibrate the battery. For all others, iOS calibrates the battery automatically.

  1. Drain your iPhone’s battery until it shuts off.
  2. (Optional) Let your iPhone sit overnight to further drain the battery.
  3. Fully Charge Your iPhone
  4. With the charging cable plugged in, perform a soft reset.
    • press & release volume up button
    • press & release volume down button
    • hold side button until you see Apple logo

If you’re interested in why you performed the previous steps, the following section provides a detailed discussion of iPhone battery calibration.

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How To Calibrate the iPhone Battery (Detailed Instructions)

If you’re dubious of the steps provided above, let’s look at more detailed instructions on how to calibrate an iPhone battery. We’ll address some of the common questions, including why an iPhone (or most electronic devices) can be charged beyond 100%.

The first step is to drain the battery completely. This should be accomplished with normal use, but sometimes this may not be an option. After all, you don’t want to head off to work with 2% battery life left. Sometimes that 2% can last a few hours. It’s best to drain the battery when you can do without your device for several hours, perhaps before bedtime. If you still have a little charge left and it’s almost time to sleep, you can drain the battery more aggressively. To expedite battery drainage, turn on the flashlight, turn up the brightness, and play a video, preferably streaming over the Internet.

Once your device powers off due to insufficient battery charge, it’s best to leave it for some time. If possible, leave it overnight and don’t charge it until the following morning. This is not always an option, and if it’s too inconvenient, skip this step. Allowing the device to sit overnight will further drain the battery. You may notice that even when your iPhone runs out of juice and powers down, when you immediately plug it back in, you will see it at 2-3% charge. This is partly due to the fact that some battery life was remaining when it powered down. To keep your data safe, iOS has to power down before the battery is fully drained. Otherwise, it would shut off without being able to save its state to secondary storage.

Next, plug your iPhone into the charger. Keep it in the charger until it’s at least 100% charged. If possible, keep it in the charger longer. According to Apple, 100% means that you will get the expected battery life, but the device can charge beyond this.

So, here’s how things work: Apple does in fact display the iPad (and iPhone and iPod Touch) as 100 percent charged just before a device reaches a completely charged state. At that point, it will continue charging to 100 percent, then discharge a bit and charge back up to 100 percent, repeating that process until the device is unplugged.

Doing so allows devices to maintain an optimum charge, Apple VP Michael Tchao told AllThingsD today.

“That circuitry is designed so you can keep your device plugged in as long as you would like,” Tchao said. “It’s a great feature that’s always been in iOS.”

Keeping the device in the charger after it reaches 100% will ensure it is fully charged. Two additional hours should do it.

It is best to charge your iPhone when it is off. After you plug in the charger, your iPhone will automatically start up in a few minutes. When it is back online, simply hold down the sleep/wake button and slide your finger over the off switch. Your iPhone will charge faster when it is off. It will also generate less heat, which will extend overall battery life.

If you turn your iPhone off to charge, make sure to estimate how long it will take to charge beyond 100%. Three hours is a safe bet for an iPhone 14 Pro Max. An old iPhone 6 will charge to 100% in three hours, but the extra two hours ensures that it is fully charged — beyond 100%.

Newer iPhone models, such as the 14 Pro Max, may take longer to charge, depending on the power source. This device, in particular, has a much larger battery than any other iPhone. An iPhone 14 Pro Max can only use 27 watts when charging. If your charger puts out more current, the iPhone’s power IC will only use 27 watts.

Sometimes I prefer to charge my iPhone 14 Pro Max with an older Apple 5 watt charger. Doing so minimizes heat and preserves battery life. Of course, it takes much longer to charge the battery fully. However, if I shut down my iPhone, it charges fully from a completely drained battery in 5 hours. I can use my iPhone when charging, and it’s still cool to the touch. However, when I calibrated my iPhone 14 Pro Max a few days after purchase, I turned it off while charging.

Now that you fully charged your iPhone, you should perform a soft reset. Unlike other reset options, a soft reset will not delete apps or data from your iPhone. Press and release the top volume button once. Do the same with the bottom volume button. Finally, hold the side button until you see the Apple logo. Your device will boot up with cleared data cache. Remove the charging cable when your device is up and running.

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Why Calibrate iPhone Battery?

Lithium-ion batteries degrade as they age and undergo repeated charging and discharging cycles. Operating systems, such as iOS, track the battery’s operating range. Regardless of wear and age, battery tracking requires occasional adjustment.

Nonlinear vs. Linear Aging Models for Lithium Ion Batteries

Battery calibration helps iOS re-calculate the range of battery life. One should calibrate the battery periodically (every 1 – 3 months) and after every major iOS update. If you upgrade iOS and notice diminished battery life, inaccurate battery metering or unexpected shutdowns, try calibrating the battery before anything else.

Battery University, an online authority on batteries of all types, recommends calibrating smart batteries:

The chemical battery representing the actual energy storage remains the master while the digital battery provides peripheral support by relying on the information obtained from charge and discharge cycles. But like all fine machines, precise settings begin to shift and need adjustment. The same happens with an SMBus battery that also require periodic calibration. The instructions for an Apple iPad reads: “For proper reporting of SoC, be sure to go through at least one full charge/discharge cycle per month.

Graph showing the necessity of periodic iPhone battery calibration.
image credit:

It’s important not to confuse calibration with regular charging practices. Your iPhone’s battery will last longer if you charge your device often, before it gets down to 0%. Ideally, you should plug your device into a charger before it goes below 20%. These are ideals and not practical for most people. In real life, many people need a full day’s charge. With battery replacements from Apple as low as $49, it’s an easier solution than closely-managed charging. For those who love fiddling and want to keep their battery in optimal condition, please read “How To Extend iPhone Battery Lifespan”.

With every iOS update, new features are added, some of which affect battery life. Apple’s engineers often improve some aspects of battery life, while also introducing battery-intensive features, such as background updates. Allowing the battery to fully drain and recharge calibrates iOS to detect the full range of battery life. Some people are skeptical of this theory, and since few know the inner workings of iOS, it may sound superstitious. Research and experience have proven otherwise.


iPhone Battery Calibration Myths Debunked

iPhone Battery Calibration Myths

A popular iPhone battery calibration guide instructs users to drain and charge the battery twice, among other odd tasks such as turning off Location Services. It’s not only unnecessary but will shorten your iPhone battery’s lifespan.

Your iPhone has 500 charge cycles before battery “health” dips below acceptable levels (80%). If you use up two every time you calibrate, you’ll need to replace the battery sooner than you should.

To calibrate your iPhone’s battery, use it as you usually would. When your battery’s charge is below 10%, it’s an excellent time to run down the battery and calibrate.

There’s no good reason to damage your iPhone battery because of misinformation. Our calibration guide derives from Battery University and other high-quality, authoritative sources. The ones suggesting these bizarre steps have no definitive source backing them up.

Some websites claim calibration is unnecessary or undesirable. They're incorrect. Apple admits that iPhone batteries require periodic calibration.
Apple admits calibration is a thing. They added battery calibration to iOS 14.5, and it’s still in iOS 16.3. Maybe these guys didn’t get the memo?

Dubious sources claim that Apple quietly fixed the “problem” with lithium-ion batteries, and they no longer require calibration. That’s false. Doing so would require changing the laws of physics.

Apple directly acknowledges that calibration is a real thing. They prefer to call it recalibration, which implies an iPhone’s battery is factory-calibrated before it ships.

Apple added battery recalibration to iOS 14.5, retaining the feature in iOS 16.2.
Apple added battery recalibration to iOS 14.5, with the feature retained in iOS 16.3. It’s a real thing, and virtually every lithium-ion battery-powered device needs to be calibrated (or recalibrated, if you prefer) periodically as the battery ages or until we use different materials in batteries.

Since lithium-ion batteries vary in capacity (within acceptable manufacturing tolerances), factory calibration makes sense. Not every brand-new iPhone battery is exactly the same; thus, Apple must establish the 0% to 100% range through calibration.

As the battery ages, the user or Apple service technicians must recalibrate it. There are numerous user accounts of Apple Store technicians calibrating iPhone batteries.

Apple didn’t quietly fix how atoms behave because that’s impossible with today’s technology. After some use, your battery’s capacity will decline. There’s simply no way around that.

Apple created new software for iOS that automatically recalibrates your iPhone. You can facilitate this process by draining your battery when it’s close to 0% and fully charging it. We tested this out, and it hastens Apple’s automatic recalibration.

Apple’s recalibration waits until your phone’s charge hits 0% and goes back up to 100%, which will likely happen through typical usage. If anything, Apple’s automatic recalibration shows that we were right all along. We based our article on excellent sources like Apple and Battery University.

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Make Your iPhone’s Battery Last Longer

A lot of people visit this site because their iPhone’s battery is shot. Calibration can help in some cases, but it is not a panacea. If calibration doesn’t improve your iPhone’s battery life, it may be time to replace the battery. Fortunately, you can prolong the lifespan of your new battery by following a few tips. For more information, please read “How To Extend iPhone Battery Lifespan”.


More Information

Many users are skeptical of this process and feel it is superstitious. I hope I have shed light on the reasons why you should calibrate your iPhone battery. If you doubt this article, take screenshots of your battery life (Settings > General > Usage) before and after conditioning the battery. I have found this process to work. Of course, your battery may drain at different rates depending on use. For more information and tips about lithium-ion batteries, please read this article.



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