How to Calibrate an iPhone

Readjust the motion sensors, Auto-Brightness, Home button, and battery

Women using iPhone and analog compass devices.

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iPhones are prized for their reliability. However, some of their features can become less accurate or responsive over time, making it difficult to use certain apps.

If your iPhone isn't working the way you expect it to, here are a few settings you can adjust. Most of them aren't necessary upkeep, like an oil change for your car. But it never hurts to play around with settings occasionally to see if you can get your device working more to your liking.

These instructions apply to devices running iOS 11 and later.

How to Calibrate iPhone Screen Brightness

Sometimes you might notice your iPhone's Auto-Brightness sensor isn't working properly, as indicated by the phone responding inappropriately to changes in lighting. The issues may come up because Auto-Brightness adjusts partly based on where you had the value set when you turned the feature on.

Here's how you recalibrate it:

  1. Go to Settings. Go to General, and then tap Accessibility.

    General and Accessibility menus in Settings on an iPhone
  2. Select Display Accommodations, and then tap the switch next to Auto-Brightness to off/white. Move to a dark or dimly lit room, and then manually turn the Brightness all the way down so that the screen is as dark as possible.

    You can access the brightness settings from anywhere on the iPhone by swiping up from the bottom edge of the screen (or down from the top on an iPhone X) to open the Control Center.

    Turning off Auto-Brightness and then adjusting the brightness on an iPhone
  3. Swipe Auto-Brightness into the green On position, and then move back into a room with regular lighting to see if your auto-brightness is working better.

How to Calibrate iPhone Motion Sensors/Compass

Many apps use the iPhone's motion sensor, its accelerometer, and its compass, so when any one of these stops working properly, it can make life frustrating. Fortunately, your iPhone will recalibrate them automatically as long as your Location Services are switched on.

Here's how to make sure that your device is handling this for you:

  1. Open Settings, and then select the Privacy heading. Tap Location Services.

    Privacy and Location Services settings on an iPhone
  2. Make sure the Location Services toggle is on/green, and then scroll down and tap System Services. On the next screen, toggle Compass Calibration and Motion Calibration & Distance to the on/green positions.

    Turning on Compass Calibration and Motion Calibration & Distance settings on an iPhone
  3. Now, your iPhone will use your location data to ensure your gyroscope, GPS, compass, and accelerometer are working properly.

Users with older versions of iOS may need to recalibrate the Compass and motion sensor by opening Compass and going through a little mini-game that requires you to roll a red ball around a circle.

How to Calibrate iPhone Battery

An iPhone with the
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It might seem strange to say you can calibrate the iPhone's battery, but you can, at least in the sense of calibrating how the phone monitors and reports the percentage of remaining battery power. This is needed whenever the iPhone begins giving inaccurate percentages, either showing a low percentage when it ends up lasting an hour or two longer or showing a healthy supply of battery power only to shut down suddenly.

  1. Fully discharge the phone, using up the battery power until it shuts off.

  2. Leave the phone discharged and unplugged overnight in order to ensure the battery is completely drained.

  3. While the phone is still powered down, charge it for a couple of hours longer than is usually necessary to bring it to '100%' capacity.

  4. Reboot the phone, then perform a soft reset (aka warm reset).

The method for performing a soft reset varies with the particular iPhone model you have:

  • For models earlier than the iPhone 7 (e.g. iPhone SE, 6S, 6, 5S, 5, 4S, 4), simultaneously hold the Sleep/Wake button and the Home button for around 10 seconds.
  • For the iPhone 7 and 7 Plus, you have to hold the Volume Down button and the Sleep/Wake button for about 10 seconds.
  • For the iPhone X, 8, and 8 Plus, press and release the Volume Up button, press and release the Volume Down button, and then finally press and hold the Side button until the Apple logo appears.

Once all of the above has been completed, your phone should be able to give a more accurate indication of its battery status, although if problems persist it may be necessary to replace the battery altogether.