To turn off Auto-Brightness on an iPhone 15, open Settings, tap Accessibility, tap Display & Text Size, then scroll to Auto-Brightness and turn it off. The switch is not on the Display & Brightness screen, which is why many people cannot find it.
Applies to: iPhone 15, iPhone 15 Plus, iPhone 15 Pro and iPhone 15 Pro Max.
What Auto-Brightness does, and what changes when you turn it off
Your iPhone has an ambient light sensor, a small sensor that measures how much light is around you. The phone uses it to lower the screen brightness in dark places and raise it in bright places. This behavior is called auto-brightness, and it is on by default. While it is on, you may notice the brightness slider moving by itself as the light around you changes.
When you turn Auto-Brightness off, the screen stops following the room light and stays at the level you choose with the brightness slider. That is useful if the screen keeps dimming while you read, show photos to someone, follow a recipe or use the phone as a reference screen. The trade-off is that you have to change the level yourself when you walk from a dark room into sunlight, or the other way around.
There is also a battery trade-off. Brightness can affect battery life, and you can get the most from the battery by letting auto-brightness adjust the display or by dimming the screen. A screen left at a high level all day will use more power than one that adapts. When the battery is getting low, turning on Low Power Mode from Control Center dims the display and cuts background activity in one tap.
Turn off Auto-Brightness on iPhone 15
You do not need a computer or any extra app for this. The steps are the same on all four iPhone 15 models.
- Open the Settings app from the Home Screen. The main list of settings appears.
- Tap Accessibility. This screen holds the vision, hearing and touch options.
- Tap Display & Text Size. A long list of display options opens, including text and contrast settings.
- Scroll to Auto-Brightness. Keep scrolling if you do not see it right away, because the list is long.
- Tap the Auto-Brightness switch to turn it off. The change takes effect immediately, and the screen stays at its current brightness until you change it.
The same path appears in Apple’s article on how to adjust the brightness and color temperature on your iPhone or iPad.
Set the brightness yourself
With Auto-Brightness off, the brightness slider is the only thing that sets the level in normal use. There are two places to reach it. Use Control Center for quick changes and Settings when you are already adjusting other display options.
From Control Center
- Swipe down from the top-right corner of the screen. Control Center opens.
- Drag the brightness bar up to make the screen brighter or down to make it dimmer. The screen changes as you drag.
Control Center changes the brightness level only. It does not have an Auto-Brightness switch, so you cannot turn the feature off from there.
From Settings
- Open Settings and tap Display & Brightness.
- Drag the brightness slider to the right or left until the screen is comfortable.
Check that it worked, or turn it back on
To confirm the change, set a brightness level, then move between a dim room and a bright one. With Auto-Brightness off, the brightness slider should stay where you left it instead of moving by itself.
To undo the change, go back to Settings > Accessibility > Display & Text Size and turn Auto-Brightness on again. Nothing else is reset, and you can switch it as often as you like.
Why the screen can still dim or change
Auto-Brightness is only one of several features that affect how the iPhone 15 screen looks. If the display still changes after you turn it off, one of these is the usual reason.
| Feature | What it does | Where to check |
|---|---|---|
| Low Power Mode | Reduces display brightness and sets Auto-Lock to 30 seconds to save battery. The battery icon turns yellow while it is on. | Settings > Battery > Power Mode |
| Heat protection | The display dims or goes black when the iPhone gets too warm, until it cools. | No setting; cool the phone |
| True Tone | Adjusts the color and intensity of the display to match the light around you. | Settings > Display & Brightness |
| Night Shift | Shifts colors to the warmer end of the spectrum, by default from sunset to sunrise. | Settings > Display & Brightness > Night Shift |
| Always-On display (iPhone 15 Pro and iPhone 15 Pro Max) | Dims the Lock Screen when the phone is locked or idle. | Settings > Display & Brightness > Always On Display |
Low Power Mode is on
Low Power Mode reduces display brightness as part of saving battery, even when Auto-Brightness is off. The easy sign is a yellow battery icon in the status bar. To turn it off on an iPhone 15, go to Settings > Battery > Power Mode, then tap Low Power Mode. If your Battery screen has no Power Mode row, look for the Low Power Mode switch on the Battery screen itself, which is the layout on earlier models. You can also use Control Center: swipe down from the top-right corner of the screen and tap the battery icon.
Low Power Mode turns itself off when the phone charges to 80% or higher. If your iPhone supports Adaptive Power and it is turned on, Low Power Mode turns on by itself when the battery goes below 20%, so a dimmer screen at low battery can be expected behavior.
The iPhone is too warm
A dimmed or black display is one of the things that happens when an iPhone gets too hot, along with slower charging and a weaker cellular signal. This protection is not a setting and it is not tied to Auto-Brightness, so there is no switch for it. It commonly shows up during navigation in a hot car, long gaming sessions, heavy camera use or wireless charging.
The fix is to let the phone cool. Turn it off, move it to a cooler place out of direct sunlight and wait. Apple’s recommended range for using the iPhone is between 32 and 95 degrees Fahrenheit (0 and 35 degrees Celsius), and it shouldn’t be left in a parked car. Brightness returns to normal once the phone has cooled.
True Tone or Night Shift is changing the color
These two features change color, not the brightness level, but the effect can look like dimming. True Tone uses sensors to match the color and intensity of the display to the surrounding light. Night Shift makes the screen look warmer and more yellow in the evening. Both are in Settings > Display & Brightness, and each can be turned off separately from Auto-Brightness. For Night Shift you can also open Control Center, touch and hold the brightness control, and tap the Night Shift button.
The Lock Screen looks dim on a Pro model
On the iPhone 15 Pro and iPhone 15 Pro Max, Always-On display is on by default. It dims the screen when the phone is locked or idle and can go completely dark when the phone is face down or in a pocket. That is separate from Auto-Brightness. If you do not want it, go to Settings > Display & Brightness > Always On Display and turn it off.
Troubleshooting
You cannot find the Auto-Brightness switch
Make sure you are in Accessibility > Display & Text Size and not in Display & Brightness. The two screens have similar names, and only the Accessibility one has the switch. Then scroll through the whole list, because the screen holds many options.
Brightness is not adjusting the way you expect
If you left Auto-Brightness on, or turned it back on, and the screen does not seem to react correctly to the light around you, try turning Auto-Brightness off and then on again.
The setting is locked or keeps changing on a work phone
If your iPhone 15 was issued by an employer or school, the organization may manage some settings on it. Ask your IT administrator before trying to work around a setting you cannot change.
The screen stays dim after the phone has cooled and Low Power Mode is off
Go through the table above once more, then set the brightness bar in Control Center to the top. If the display is still unusually dim at the highest level, contact Apple Support, because that points to a problem that settings cannot fix.
Frequently asked questions
Why is Auto-Brightness not in Display & Brightness?
The switch sits with the accessibility options, under Accessibility > Display & Text Size. The Display & Brightness screen has the brightness slider, True Tone and Night Shift, but not the Auto-Brightness switch.
Does turning off Auto-Brightness drain the battery?
It can, because brightness affects battery life. If you turn the feature off, keep the slider at a moderate level and lower it in dark rooms to limit the extra battery use.
Is it safe to leave Auto-Brightness off?
Yes. It is a normal iPhone setting, and you can turn it back on at any time. The practical costs are more manual adjusting and possibly shorter battery life if you keep the screen bright.
Can I turn off Auto-Brightness from Control Center?
No. Control Center has the brightness bar and, when you touch and hold it, a Night Shift button, but the Auto-Brightness switch is only in Settings.
Does turning off Auto-Brightness also turn off True Tone or Night Shift?
No. They are separate features with their own switches in Settings > Display & Brightness. Some display accessibility settings, including Invert Colors, Grayscale and Increase Contrast, might turn off True Tone.
Are the steps the same on the iPhone 15 Pro?
Yes. The Auto-Brightness path is the same on all iPhone 15 models. The only difference in this guide is the Always-On display, which applies to the Pro models.
Will the screen still turn off by itself?
Yes. Auto-Brightness controls how bright the screen is, not how long it stays on. If you want the display to stay awake longer, keeping your iPhone screen on explains the options.
Once Auto-Brightness is off, set a level you like in Control Center and use the phone for a day. If the battery drains faster than you want, lower the slider a little or turn Auto-Brightness back on in the same place. A shorter Auto-Lock time also helps; making an iPhone 15 screen turn off sooner shows where to set it.
Related: turning off background app refresh and why your iPhone battery icon is yellow.
Matt Jacobs has been working as an IT consultant for small businesses since receiving his Master’s degree in 2003. While he still does some consulting work, his primary focus now is on creating technology support content for SupportYourTech.com.
His work can be found on many websites and focuses on topics such as Microsoft Office, Apple devices, Android devices, Photoshop, and more.