How to Calibrate an iPhone

Readjust the motion sensors, auto-brightness, home button, and battery

iPhones are prized for reliability. However, some features become less accurate or responsive over time, making it difficult to use certain apps. If your iPhone isn't working the way you expect, here are a few settings you can adjust. Most aren't necessary upkeep, like an oil change for a car. But it doesn't hurt to calibrate the settings to see if your device will work more to your liking.

These instructions apply to devices with iOS 11 and later.

How to Calibrate iPhone Screen Brightness

If the iPhone Auto-Brightness sensor isn't working properly, the phone responds inappropriately to changes in lighting. The issue may come up because Auto-Brightness adjusts partly based on where the value was set when the feature was turned on.

Here's how to recalibrate the Auto-Brightness sensor:

  1. Open the Settings app.

  2. Go to General, then tap Accessibility.

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

    To access the brightness settings from anywhere on the iPhone, swipe 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
  4. Turn on the Auto-Brightness toggle switch, then move to a room with regular lighting to see if the auto-brightness works better.

How to Calibrate iPhone Motion Sensors/Compass

Many apps use the iPhone motion sensor, accelerometer, and compass. When any one of these stops working properly, the iPhone recalibrates the app automatically as long as Location Services are switched on.

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

  1. Open Settings.

  2. Select Privacy, then tap Location Services.

    Privacy and Location Services settings on an iPhone
  3. Turn on the Location Services toggle switch, then scroll down and tap System Services.

  4. Turn on the Compass Calibration and Motion Calibration & Distance toggle switches.

    Turning on Compass Calibration and Motion Calibration & Distance settings on an iPhone
  5. The iPhone will use your location data to ensure the gyroscope, GPS, compass, and accelerometer work properly.

To recalibrate the Compass and motion sensor on older versions of iOS, open Compass and play the mini-game by rolling a red ball around a circle.

How to Calibrate iPhone Battery

The iPhone battery needs to be calibrated when the phone gives inaccurate percentages. The phone may show a low percentage but last an hour or two longer. Or, it may show a full battery and shut down suddenly. Calibrate the iPhone battery to fix the way the phone monitors and reports the percentage of remaining battery power.

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

  2. Leave the phone discharged and unplugged overnight to completely drain the battery.

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

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

The method to perform a soft reset varies with the iPhone model:

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

When the phone is reset, it should give a more accurate indication of its battery status. If problems persist, it may be necessary to replace the battery.