The iPhone utilizes a sophisticated set of sensors for many of its operations, from automatically adjusting screen brightness based on the light around you, to detecting motion for various apps and screen orientation.
While these sensors should work out of the box, sometimes they don’t, and at times they may stop working properly. When that happens, the iPhone’s sensors will need to be recalibrated. Or you might need to turn the sensors back on.
What an iPhone’s brightness sensors do
While the iPhone generally does the work of multiple tools, it becomes little more than a paperweight if you can’t see the screen. Fortunately, the iPhone automatically adjusts its display brightness down to avoid straining your eyes at night, and turns the brightness up during the day to make the screen more visible.
While different people have different preferences for the brightness baseline, and you can dial those in manually, the brightness auto-adjust is extremely important. With just a few steps you can recalibrate your sensor, helping it to accurately detect how light or dark a room is, and adjust screen brightness accordingly.
Note that these instructions are for auto-calibrating brightness in iOS 11 and above. In iOS 10 and below, the “Auto-brightness” adjustment is found in the “Display and Brightness” section in your Settings app.
How to calibrate your iPhone’s brightness sensors
1. Open the Settings app.
2. Scroll down to and tap “General.”
3. Scroll down to and tap “Accessibility.”
4. Scroll down to and tap on “Display Accommodations.”
5. Tap on “Auto-Brightness” so that the setting slides over to green (or if it is green and doesn’t seem to be auto-adjusting, you might need to turn it off then back on to recalibrate).
This will allow your iPhone to self-calibrate and automatically adjust to ambient light conditions. However, if auto-adjusting has been activated and recalibrated but you’re still having trouble seeing your display, there may be a problem with the general brightness of your display. To manually adjust it:
1. Tap “Settings.”
2. Scroll down to tap “Display & Brightness.”
3. Move the slider left or right depending on your preference (your screen will brighten or darken as you adjust).
How to calibrate an iPhone’s motion sensor
The motion sensor affects some of the phone’s basic operations, its various movement-based apps (such as Health), as well as some games. Racing games, for example, use the motion sensor extensively. And when you turn your phone sideways, the motion sensor is what turns the picture to fit the widescreen.
If any of these aren’t working properly, your motion sensor may need to be recalibrated or activated.
1. Click on “Settings.”
2. Scroll down to and tap “Privacy” (it should be the last item in the group that starts with “General”).
3. Tap on “Location Services” (it should be the top item).
4. Scroll down to and tap “System Services” (it should be the last item).
5. Tap both “Compass Calibration” and “Motion Calibration & Distance” to toggle into the “On” position. If your calibration seems off but these are both showing green, try turning them off and then on again to recalibrate.