How to Calibrate iPhone Battery

How To Calibrate iPhone Battery

updated by Chad Evans
July 5, 2022 at 3:57 p.m.

The iPhone features remarkable battery life, however, not every user experiences peak performance. It is essential to calibrate the lithium-ion battery 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 iPad and iPod Touch, as well as most other devices with lithium-ion “smart” batteries.

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
image credit: Journal of Power Sources; Many bloggers with good intentions try to reduce calibration to a myth. “Of course, the smart people at Apple figured all of this out.” Yes and no. Keeping track of a lithium-ion battery’s condition is no easy task. With more electric vehicles on the road, it’s becoming essential, as drivers need an accurate range. Only the newest iPhones can self-calibrate, along with select Android devices, like Google Pixel phones. For most devices, you’ll need to calibrate them yourself once in a while.


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 need for 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 11, 12, 13 Running iOS 14.5 or Later Don’t Require 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.

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 13 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.

Step By Step Battery Calibration

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%, and reset it by holding down the sleep/wake and home buttons until you see the Apple logo.

  1. Use your iPhone until it shuts off automatically. If it is near 0% battery life and you want to drain it faster, turn on the flashlight, turn up screen brightness all the way and play a video, preferably streaming from the Internet.
  2. Let your iPhone sit overnight to drain the battery further.
  3. Plug your iPhone in and wait for it to power up. Make sure to use the charger supplied by Apple or one that runs at the same wattage and amperage.
  4. Hold down the sleep/wake button and swipe “slide to power off”.
  5. Let your iPhone charge for at least 3 hours. Older iPhones should be charged for 5 hours. The charge progress indicator is not displayed while your iPhone is turned off.
  6. With the charging cable still connected, press the sleep/wake button for about a second to start up your iPhone.
  7. When the iPhone has booted up, hold down the sleep/wake and home buttons until you see the Apple logo. If you have a newer iPhone, without a physical Home button, hold the volume up and sleep/wake button.
  8. When your iPhone is back online, remove the charging cable.

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 11. My 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 13 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 13 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.

I prefer to charge my iPhone 13 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 3-4 hours. I can use my iPhone when charging, and it’s still cool to the touch. However, when I calibrated my iPhone 13 Pro Max a few days after purchase, I turned it off while charging.

Now that your device is fully charged, you should reset it. This is done by holding down the sleep/wake button (on the top of the device) and home button, until the Apple logo appears. If you have a newer iPhone, without a physical Home button, hold the volume up and sleep/wake button. Your device will boot up and is now reset. Remove the charging cable when your device is up and running.

Addressing the Critics

Numerous critics of battery calibration have emerged. They post (often nasty) comments and there’s even a top-ranking article debunking battery calibration, specifically mentioning this Appledystopia article. Riddled with contradictions, confusion and conflation, their main argument is that completely draining a lithium-ion battery is harmful. This is partially true, but battery calibration is not done every day. Battery calibration is performed periodically, no more than once every one to three months.

Draining your iPhone’s battery isn’t that harmful. Most people do this quite often, in the process of using their iPhone throughout the day. It’s not optimal, but it will not totally destroy your battery. The benefit of calibration outweighs running your iPhone down to 0% once every few months. Your device will have a more accurate battery meter. With more accurate battery metering, there won’t be any unpleasant surprises, such as missing that important conference call because your iPhone went from 30% to 5% in 30 minutes.

On the opposite side, they argue that fully charging an iPhone also damages the battery. Apple already has technology in place to carefully manage the last 20% of the charging process. Once your battery charge progresses over 80%, the iPhone’s power IC reduces charge current. This is known as a trickle charge. Reducing the charge stresses the battery less than running at full current. This is all the more reason you need to calibrate your iPhone battery. Your iPhone relies on accurate battery metering to determine when the trickle charge starts. Calibration helps ensure that the iPhone’s smart battery is accurate.

Critics suggest that calibration, by running the battery between two extremes, will do more harm than good. Again, this is a process that’s done once every 1-3 months. Most people drain their iPhone battery from use. They charge their iPhone all the way. If you do this methodically and throw in a system reset, you’ve just calibrated your iPhone. There’s nothing mysterious or damaging about this process. Everything is done within normal operating parameters of the device. People run their battery from 0% to 100% every day, for years on end. The whole point of calibration is to have an accurate battery meter. Performing calibration periodically won’t diminish iPhone battery lifespan. In fact, you can get more life out of a failing battery with calibration. Calibration ensures that processes such as trickle charging are more precise, as they rely on accurate battery statistics. Read the comments — they’re testimonials to battery calibration.

Critics of this article don’t tell their readers to turn off their iPhones while charging. When an iPhone is on and plugged in, it generates more heat while charging, which will shorten the battery’s lifespan. Despite this fact, most people will leave their iPhone on while charging. They’ll even continue to use it, even when it’s warm to the touch. It’s easier and more convenient to do so, but it does harm the battery.

The Appledystopia battery calibration guide, however, recommends turning the iPhone off, which charges the battery with less heat than typical charging.  The battery also charges faster this way, as the device is no longer consuming power. The notion that calibration harms a battery is bunk. Everything is done within normal operating procedures. iPhone users run their battery down every day. They charge their device to 100% all the time. To label this behavior damaging is delusional. Appledystopia isn’t trying to alter the way you use your iPhone every day. This article is simply outlines a procedure to calibrate the iPhone’s battery meter. I feel sorry for the poor soul who’s suckered into using 60% of their battery range, so they can make their battery last for a few more weeks. Such people can’t see the forest for the trees!

Critics of this article contradict themselves. One one hand, they suggest that Apple successfully manages all aspects of battery charging, including calibration. They silently fixed this issue, according to some. Then, in their same article or comment, they contend that draining and fully charging the battery is incredibly harmful. Which one is it? Does Apple provide users with a device that’s harmful to fully charge and discharge? Or do they manage every aspect of charging, including calibration? The answers are a bit complex, but they’re not the polarized contradictions that my critics spew forth. It’s safe to fully charge and discharge your battery, but not optimal.

You don’t need to calibrate your device if you have an iPhone 11 or newer running iOS 14.5 or later. iOS will take care of this for you. This is proof that for all these years, calibration has been real, and finally, Apple has addressed it. Apple has indeed made advances in battery management, but they now acknowledge battery calibration, yet the critics are still in denial. In my research, I have also found iPhone users who had their batteries calibrated at the Apple Store.

Some brands of smartphone do not need to be calibrated. Google’s Pixel line doesn’t need calibration, and they specifically mention this on their battery care page. It’s unclear how they manage diminishing battery lifespan on their device. Critics of this article claim that Apple has done the same thing, but they won’t mention it. That’s a big assumption to make. They could easily report this self-calibrating feature on their battery management page.

It makes sense for them to remain silent about calibration. Most people will just go to the Apple Store and maybe purchase something while there. It makes their product seem inferior. They have made no indication whatsoever that battery calibration is part of iOS 13 or any new release. Battery calibration requires that the user run the battery down to 0% and back to 100%, to determine the full range. Apple may do this discretely if this behavior occurs. If that’s the case, however, users can still follow this guide to initiate calibration themselves. Some may always top off their iPhone and never run the full range. When Apple admits that battery calibration is no longer necessary, I will be the first to update this guide. Until then, I’ll stick with the evidence at hand.

Critics take a cheap shot, claiming that I advocate turning on the flashlight, amplifying screen brightness and other measures to rapidly drain the battery. Yes, but only if you’re close to 0%. My critics didn’t miss that, yet their writing indicates that this is a long-running process. It’s their pathetic attempt to create a straw man. I never suggest turning every bell and whistle on and all the way up, in order to drain an iPhone from 100% to 0%. That’s an intentional deception put forth by my critics.

Battery calibration isn’t just backed up by anecdotes. Although many people have noticed significant improvement in battery meter accuracy, there’s proof beyond these accounts. Battery University provides some of the best information on lithium ion battery care. They wrote a whole article on how to calibrate a smart battery, which has been referenced by Appledystopia several times. Their guide is an excellent resource, however, it’s not specific to the iPhone.

If battery calibration works for you, or not, let Appledystopia know! Drop a comment below.

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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  1. .

    Incidentally, my phone 4s would often shut down at up to 24%. When it comes back on, it still thinks it’s at 24%, or wherever it was when it shut off.

  2. Good morning. Can i using my i phone for browsing and anything, while my iphone during charging battery. That is ok or will make problem. Thank u

    1. I advise turning your iPhone off while charging, if possible. The battery will last longer if you do that. You can probably feel it getting warm when you use it and charge it at the same time. Heat will eventually shorten the lifespan of the lithium-ion battery.

  3. After updating to iOS 8.1.2 my iPhone 6+ had this problem. I did as you told. Now it’s back to normal. Thnx man thnx a lot

  4. My iPhone5 recently suffered battery problem – the battery showed around 35% remianing but would suddenly go dead. I thought it could be a calibration problem and googled this subject, and I found that Apple knew about the sudden death issue and has a free battery replacement program for phones sold between Sep 2012 and Sep 2013. Go to the battery rpelacement program website, key in the serial number to check eligibility. If YES, make an appointment with Apple. I just did this and got my battery replaced free of chrage. Just thought I share this info.

  5. Hi, thanks for the article. I am unclear on what benefit doing the reset provides, can you enlighten me? Thanks!

    1. The reset clears cached system and application data, including battery data. Beyond calibration, it is something one should do on occasion. If your device is slow or something has gone awry (Bluetooth problems, for example) this soft reset fixes most problems. In fact, this is the first thing an Apple Genius will tell you to do if you have a problem. They may just be channeling Roy from the IT Crowd, but I think it works.

      Anytime I have an iOS problem or my device seems sluggish, I do a soft reset and it is back to normal. Of course, I don’t need to do this often. iOS is pretty solid…

      1. Interesting!

        Firstly, thank you for the clear article. Last night my battery went straight from 9% to 1% so I’m planning on calibrating it tonight.

        Secondly, regarding the soft reset, I always just held the power button and swiped to power off. Should I assume that normally shutting down and restarting doesn’t clear the same caches(inc. battery capacity meter)?

        Reading up on it, it seems the soft reset is simply what you do if you can’t do the swipe to power off because the phone has frozen but I’ll keep checking.

        On a side note, here’s a little charging forget-me-not I use to get the maximum effect when I don’t have enough time(e.g. getting ready to go out and noticing the battery is around 20%):

        If I turn the phone off while charging, I keep it plugged in while powering back on just before I leave. I used to just unplug the phone and turn it on while leaving but booting devices uses a fair bit of battery power while they load all the bits up at full speed. It could save you from wasting 1-2%, especially if you could only charge for around ten minutes!

        1. The reset (home + sleep/wake) is necessary to reset battery life data that is cached. I also do it whenever my iPad or iPhone are a bit sluggish. It works every time! The Apple Geniuses also reset the device whenever someone has a problem. It is the first thing they do, because it fixes so many problems.

          Thanks for the tip!

  6. i just want to ask if using app like battery doctor good? because i think the information like remaining minutes to charge is not accurate.. do you suggest charging iphone without any battery app? thank you

    1. I suggest turning off your device while charging whenever possible. Of course, when you first plug your device into the charger, it will start up. I shut it down after this happens.

      There are a few reasons why I do this. First, it keeps the device cooler while charging. Since heat damages lithium ion batteries, the cooler the device, the longer the battery will last. Second, the device charges much faster when it is off. Even if it is on standby and not being used, it doesn’t charge as fast as if it is off.

      Of course, I don’t always do this. Sometimes I will plug in the charger and update all of my apps. I try to not do this very often. Ideally, I like to charge my device all the way up (while off), unplug it, and then run app updates.

      I have heard of battery doctor, but I haven’t tried it. I don’t have any problems with poor battery life. I will check it out and maybe write a review.

          1. While I can’t do a soft reset, I am able to switch the phone off without the power button:

            1) Enable Assistive Touch
            2) Press the on-screen Home button
            3) Choose ‘Device’ from the menu
            4) Press and hold the ‘lock screen’ icon. This simulates the power button and you’ll get the ‘slide to power off’ option 🙂

            I tried the soft reset but holding my home buttonand the lock screen icon did nothing 🙁

            This could be a good workaround if a clean shutdown resets the battery level cache, etc, like a soft reset

          2. Sorry, I just realised that powering off an iPhone without a working power button means no way to turn it back on!

            You’d have to connect it to power(computer or charger) to turn it back on. Careful!

            Also, as per your reply to my other comment, clean shut down won’t clear the battery cache.

            As for my battery, I calibrated it over the weekend(powered off for a day and a night).

            I used a Cydia app called Batterylife which lists health and current usage(as well as charging current which is great for testing how powerful a USB port or if your cable is sending the right amount).

            Prior to this, battery health was 90% after a year which sounds great but the phone would shutdown at 9%, which is why I left it powered off for so long. It would randomly turn back on if I tried and would say 6% or something then freeze and power off again.

            After calibration my battery health is now 85% but I’m hoping it’s due to the calibration and means the phone will actually run down to 1% before shutting down.

            I want to give the battery a break so I won’t test this for a few months!

  7. Will when I drawn my iPhone Battery then plugged in , any iPhone in the world will automatically boot up after its reach 15-20 % , so what I can do about it

  8. Thanks for the tips but I’ve got 1 question. How long shouls you keep your battery fully drained to get an optimal result?

    Thanks in advance!

    1. I usually try to keep it drained overnight. This also ensures that the battery will be cool when charging. It might not be ideal for many people who constantly need their iPhone. The most important thing is that the device is drained to the point that it shuts off automatically. There is some more battery depletion that happens after the device is shut off, but for the purposes of battery calibration, this is sufficient. Leaving it for a few hours after it has shut off will allow the battery to cool down and drain further. It doesn’t affect calibration, but it will help your battery last longer.

      1. hi.. it happened to me that my battery got fully drain.. then when i charge it.. my phone didnt open.. what would that mean?..

        1. You mean it doesn’t start up and show the lock screen? Did it show the battery charging screen while charging? If it just had a blank screen during the whole charging process, the battery is likely shot. Try taking it in to a repair service. If it is old, you may consider replacing it.

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