How to Disable Auto-Brightness on Your Mac

Owners of Macs with built-in displays likely know that the screen brightness can be changed via the function keys on the keyboard or in the macOS user interface via System Preferences or a third party utility. But you may have also noticed that, by default, your Mac’s screen adjusts its brightness levels automatically.
Your Mac uses a built-in ambient light sensor to detect the brightness of the room and can then automatically raise or lower your Mac’s screen brightness accordingly. In a room with low light? Your screen will dim itself so it doesn’t blast you off your couch with its insane light levels. And if you’re on a sunny beach with your laptop, it’ll automatically brighten its display to improve visibility. (If you’re on a beach with your iMac instead, well…kudos to you).
But some users prefer to have complete control over their Mac’s screen brightness and don’t want the system changing it for them. Thankfully, it’s easy to disable auto-brightness on your Mac. Here’s how.

Disable Auto-Brightness in macOS

  1. Click on the Apple Menu at the upper-left corner of your screen and choose System Preferences.
  2. mac desktop system preferences

  3. Choose the Displays pane.
  4. mac system preferences displays

  5. Under the Display tab there, deselect the Automatically adjust brightness option.

mac automatically adjust brightness
Once you deselect that option, your screen will no longer brighten or dim without your say-so! Of course, you can manually adjust that setting either from this same System Preferences > Displays > Display pane using the “Brightness” slider shown above, or you can use the appropriate function keys (or the Touch Bar) on your keyboard. Those function keys are usually F1 and F2, but you’ll note they’re the ones with the sun icons on them.
Finally, there’s one more way to disable auto-brightness functionality—by doing so for your backlit keyboard. If you’ve got a laptop where the keys glow a bit, you can again either let the Mac decide how bright to make that glow or force it to stay at a brightness level you specify. To do that, visit Apple Menu > System Preferences > Keyboard, and under the “Keyboard” tab, deselect “Adjust keyboard brightness in low light.”
mac keyboard auto brightness
To change the brightness level of this afterward, again you can use the proper function keys (usually F5 and F6) or the controls on your Touch Bar, which look like…um…little sunrises? Of which the smaller one makes the backlight dimmer? These things are hard to describe, my friends.
macbook touch bar brightness
Within System Preferences > Keyboard > Keyboard, you can also configure how long you’d like the backlight to stay on after your Mac stops being used. The keyboard backlight drains your battery, of course, so just like the display brightness, you’ll want to adjust these settings appropriate to your level of tolerance for battery usage. I like my display bright as bright can be most of the time, so I’m willing to drain my battery a bit faster to get to see my screen all lit up and stuff.
Oh, and one more thing—if you’re curious about how to adjust similar settings on the iPhone or iPad, head on over and read TekRevue’s own Jim Tanous give us his take on that!

2 thoughts on “How to Disable Auto-Brightness on Your Mac”

Avatar HEIDI says:
I am in the same situation. The Auto adjust tab is not selected. I prefer a dimmer screen and set it as such. Every time I restart it’s 100% brightness. I hate it. I know it’s a simple click of some buttons but it’s ridiculous. Ever since I did the most current Mac update this has been happening. Seems like a bug in the system. Grrr!
Avatar Cleo says:
Hello, I have a persistent problem with my iMac which is the brightness goes up to max constantly, totally unprompted and I have to keep manually pressing the brightness on the Display with the mouse as well as the dimming button on my keyboard simultaneously. There is nothing on the Keyboard to adjust the brightness (maybe that’s only for laptops) and even though I’ve unticked the ‘automatically adjust brightness’ box in Displays, it keeps doing it, even when I turn the machine on. It’s so irritating, it becomes a challenge to write these few lines let alone do any work. If you have any suggestions, please share them! Thank you so much. Cleo
Avatar ANYA says:
Hi Cleo, I’m also on an iMac and having the exact screen brightness resetting to 100% on its own. I’m hoping you or someone reading this will have found a solution by now and would be gracious enough to share it with me. The “Automatically adjust for brightness” button was never selected so the deselect the “Automatically adjust for brightness” button is no help for me. This just started happening in October 2019. It’s driving me bonkers. It resets to full brightness every time I open a new window. UGHHHH!! Anyone, please help me with this. Thanks in advance. Anya

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