To stop your iPhone screen brightness from changing on its own, turn off Auto-Brightness in Settings > Accessibility > Display & Text Size. That’s the setting most people are looking for, and it’s not in Display & Brightness, which is why it’s easy to miss. Then set the level you want with the brightness slider in Control Center.
If the screen still dims or shifts color afterward, another feature is responsible: True Tone, Night Shift, Low Power Mode, Attention Aware Features, the Always On display, or your iPhone protecting itself from heat. Each one is covered below, with what it does and whether you can turn it off.
Quick Answer
- Open Settings.
- Tap Accessibility, then Display & Text Size.
- Scroll to the bottom and turn off Auto-Brightness.
- Swipe down from the top-right corner to open Control Center and drag the brightness slider to the level you want.
- If the screen still changes, check True Tone, Night Shift, and Low Power Mode, and let a hot iPhone cool down.
In This Guide
- Before you start: what changes brightness
- Turn off Auto-Brightness
- Set your brightness manually
- True Tone and Night Shift
- Low Power Mode and Adaptive Power
- Attention Aware Features and the Always On display
- When your iPhone dims because of heat
- Which setting is changing your screen?
- Troubleshooting
- Frequently Asked Questions
Before You Start: What Changes Your iPhone’s Brightness
This guide covers current versions of iOS, including iOS 26, as of September 2026. The same settings also exist in iOS 17 and iOS 18, so the steps apply if you haven’t updated. Setting names are taken from Apple’s support pages; if a label looks slightly different on your iPhone, use the search bar at the top of Settings to find it.
Several separate features can change what your screen looks like:
- Auto-Brightness raises or lowers brightness based on the light around you, using the iPhone’s ambient light sensor. Apple turns it on by default.
- True Tone adjusts the color and intensity of the display to match the light around you. It’s also on by default.
- Night Shift makes colors warmer (more yellow) in the evening, which can look like dimming.
- Low Power Mode reduces display brightness to save battery.
- Attention Aware Features (Face ID models) can dim the screen when you’re not looking at it.
- Heat protection dims the display when the iPhone gets too hot. You can’t turn this off.
Before changing anything, notice when the screen changes. Brightness that follows the room’s lighting points to Auto-Brightness. A yellow tint at night points to Night Shift or True Tone. Dimming in the sun or while charging and gaming often points to heat.
How to Turn Off Auto-Brightness
Apple moved this switch into the Accessibility settings years ago, and it’s still there in current iOS versions.
- Open Settings from your Home Screen.
- Tap Accessibility.
- Tap Display & Text Size. Expected result: You see options like Bold Text, Larger Text, and Increase Contrast.
- Scroll to the bottom and turn off Auto-Brightness. The switch turns gray when it’s off. Expected result: Your screen now stays at the level you set, no matter how bright or dark the room is.
Apple documents this path in Adjust the brightness and color temperature on your iPhone or iPad. Apple says Auto-Brightness adjusts brightness levels based on the lighting conditions around you. With it off, remember to turn brightness down indoors and at night, because a bright screen uses more power.
Tip: Instead of scrolling through menus, open Settings, pull down on the main list to show the search bar, and type “Auto-Brightness.”
How to Set Your Brightness Manually
With Auto-Brightness off, you choose the level yourself. There are two places to do it.
From Control Center
- Open Control Center. On an iPhone with Face ID, swipe down from the top-right corner of the screen. On an iPhone with a Home button, swipe up from the bottom edge.
- Drag the brightness bar (the one with a sun icon) up to brighten or down to dim. Expected result: The screen changes as you drag and stays there.
From Settings
- Go to Settings > Display & Brightness.
- Drag the Brightness slider left or right.
For more ways to get to the slider quickly, see our guide to the iPhone brightness shortcut.
True Tone and Night Shift
These two features change the color of the screen more than its brightness, but a warmer, yellower screen often looks dimmer, so people mistake them for brightness problems.
Turn off True Tone
- Go to Settings > Display & Brightness.
- Turn off True Tone. Expected result: White areas look the same in every room instead of shifting warmer or cooler.
Apple says True Tone uses advanced sensors to adjust the color and intensity of your display to match the ambient light. If your screen seems to change slightly when you walk between rooms even with Auto-Brightness off, True Tone is the likely reason. True Tone is available on supported models; if you don’t see the switch, your iPhone doesn’t have it.
Turn off or reschedule Night Shift
- Go to Settings > Display & Brightness > Night Shift.
- Turn off Scheduled to stop it from turning on automatically, or change the From and To times.
- If Night Shift is on right now, turn off Manually Enable Until Tomorrow.
- Drag the Color Temperature slider toward Less Warm if you want to keep Night Shift but make the change subtler.
The option names on the Night Shift screen can vary slightly by iOS version. Night Shift doesn’t dim the screen by itself, but the yellow tint makes text look less bright in the evening.
Low Power Mode and Adaptive Power
Low Power Mode cuts back on background activity to stretch your battery, and according to Apple it reduces display brightness. It also sets Auto-Lock to 30 seconds and turns off some visual effects. When it’s on, the battery icon in the status bar turns yellow.
To turn it off:
- iPhone 15 and later: Go to Settings > Battery > Power Mode, then turn off Low Power Mode.
- iPhone 14 and earlier: Go to Settings > Battery and turn off Low Power Mode.
- Any model: Open Control Center and tap the battery button, if you’ve added it.
Some newer iPhones also have Adaptive Power. Apple’s Low Power Mode support page says that if your device supports Adaptive Power and it’s turned on, Low Power Mode turns on automatically when your battery drops below 20 percent. So if your screen dims every time the battery gets low, this is likely why. On supported models, look for Adaptive Power in the Power Mode settings. Adaptive Power may also make small adjustments of its own, so if you want the most consistent brightness, you can turn it off there.
Keep in mind that turning off power-saving features means your battery drains faster. Our guide to turning Low Power Mode on or off explains the trade-offs.
Attention Aware Features and the Always On Display
Attention Aware Features
On iPhones with Face ID, Attention Aware Features let the phone check whether you’re looking at it before it dims the display, lowers some alert volumes, or expands notifications on the Lock Screen. If your screen dims while you’re reading with your face partly out of view, or wearing sunglasses that block the camera, this feature may be involved.
- Go to Settings > Face ID & Passcode and enter your passcode.
- Turn Attention Aware Features on or off. Apple describes this in Change Face ID and attention settings on iPhone.
Turning it off doesn’t stop the screen from dimming before Auto-Lock; it just means the iPhone won’t use your gaze to delay that. To give yourself more time before the screen dims and locks, change Settings > Display & Brightness > Auto-Lock.
Always On display
On iPhone models that support it (iPhone 14 Pro and later), the Always On display is on by default. When you lock the phone, the Lock Screen stays visible but very dim. That’s normal and doesn’t mean brightness is broken. If you’d rather the screen go fully dark, look for Always On Display in Settings > Display & Brightness and turn it off. Apple notes the feature is off by default on iPhone Air.
When Your iPhone Dims Because of Heat
If your iPhone gets too warm, for example in direct sun, while charging, or during long gaming or video sessions, Apple says the display might dim and maximum screen brightness is reduced until the device cools down. In more extreme cases, the display can dim a lot or go black and you’ll see a temperature warning. This is a protective feature and there’s no setting to turn it off.
What to do:
- Move out of direct sunlight and out of hot places like a car dashboard.
- Stop charging and close demanding apps such as games, navigation, or the camera.
- Take off a thick case for a few minutes if the phone feels hot.
- Wait for it to cool. Normal brightness returns on its own. Don’t put the iPhone in a fridge or freezer.
Apple covers this in If your iPhone or iPad gets too hot or too cold.
Which Setting Is Changing Your Screen?
| What you notice | Likely cause | Where to change it |
|---|---|---|
| Brightness follows the room’s lighting | Auto-Brightness | Accessibility > Display & Text Size |
| Screen turns warmer or cooler between rooms | True Tone | Display & Brightness |
| Yellow tint in the evening | Night Shift | Display & Brightness > Night Shift |
| Dimmer screen and yellow battery icon | Low Power Mode | Battery (or Battery > Power Mode) |
| Dims when battery hits 20 percent | Adaptive Power turning on Low Power Mode | Battery > Power Mode |
| Dims when you look away | Attention Aware Features or Auto-Lock | Face ID & Passcode; Display & Brightness |
| Dims in sun, while charging or gaming | Heat protection | No setting; let it cool |
Troubleshooting
Auto-Brightness is off, but brightness still changes
Work down the table above. Check True Tone, Night Shift, and Low Power Mode first, since they’re the most common. If the dimming happens mostly outdoors in sunlight, heat is the likely cause, even if the phone doesn’t feel very hot.
The screen is too dim even at full brightness
Check whether Reduce White Point is turned on in Settings > Accessibility > Display & Text Size. This accessibility option lowers the intensity of bright colors and can make the whole screen look dim. Also make sure Low Power Mode is off. For more ideas, see our guide on making the iPhone screen brighter.
I can’t find Auto-Brightness in Display & Brightness
That’s expected. It lives in Accessibility > Display & Text Size, at the bottom of the list. Searching Settings for “Auto-Brightness” gets you there fastest.
Brightness keeps changing after an iOS update
Updates generally keep your settings, but it’s worth checking that Auto-Brightness is still off. After a major update, the iPhone also does background work for a while, which can make it warm and trigger heat dimming temporarily.
The screen flickers or brightness jumps randomly
Restart your iPhone. If flicker continues with Auto-Brightness, True Tone, and Night Shift off and the phone cool, contact Apple Support, since that can point to a hardware issue.
Frequently Asked Questions
Where is Auto-Brightness on iPhone?
In Settings > Accessibility > Display & Text Size, at the bottom of the page.
Does turning off Auto-Brightness drain the battery?
It can. Auto-Brightness lowers brightness in dim places automatically. With it off, a screen left bright indoors uses more power. Lower the slider when you don’t need full brightness.
Can I stop my iPhone from dimming in the sun?
Not if the dimming is caused by heat. It’s a built-in protection that you can’t disable. Keeping the phone shaded and cool is the only fix.
Is True Tone the same as Auto-Brightness?
No. Auto-Brightness changes how bright the screen is. True Tone mainly changes its color to match the light around you. You can turn off one and keep the other.
Why does my Lock Screen stay on but look dim?
That’s the Always On display, available on iPhone 14 Pro and later supported models. It’s designed to stay dimly lit while locked.
Does this work the same on older iOS versions like iOS 17?
Yes. Auto-Brightness has been in Accessibility > Display & Text Size since well before iOS 17, and the other settings in this guide are in the same places. Only the Low Power Mode path differs by model.
Summary
- Turn off Auto-Brightness in Settings > Accessibility > Display & Text Size.
- Set brightness yourself with the slider in Control Center or Display & Brightness.
- Turn off True Tone and adjust Night Shift if the screen’s color keeps shifting.
- Turn off Low Power Mode, and check Adaptive Power on newer models, if the screen dims with a low battery.
- If your iPhone dims in the heat, let it cool; that protection can’t be turned off.
Next step: Open Settings, search for “Auto-Brightness,” turn it off, and then set your brightness from Control Center.
Kermit Matthews is a freelance writer based in Philadelphia, Pennsylvania with more than a decade of experience writing technology guides. He has a Bachelor’s and Master’s degree in Computer Science and has spent much of his professional career in IT management.
He specializes in writing content about iPhones, Android devices, Microsoft Office, and many other popular applications and devices.