How to Control the Brightness for External Displays with a MacBook

It’s easy to control brightness and contrast on your MacBook display. But if you’re using an external monitor, things are a bit more complicated.

While you normally can’t use the brightness keys or system preferences to control the behavior of external hardware, some apps make it possible to do so. Apart from using the keys on your monitor, here’s what you can do to control the brightness on all of your displays.

Use ExternalDisplayBrightness to Control Your Monitor’s Brightness

ExternalDisplayBrightness is a popular app that allows you to manage the brightness of your external device. To do so, follow these steps:

  1. Download the app from the app store and hit install.
  2. During the installation, you’ll be asked for special accessibility access. You’ll need to grant them if you want the app to serve you properly.
  3. Set the preferences by choosing the keys which you’d like to use to regulate brightness for your monitor. Set one key for increasing and another for reducing the brightness.
  4. Don’t click Quit; just close the window. That way the app will be active.

Once you’ve configured ExternalDisplayBrightness, use the keys that you selected to change the brightness on your external screen.

This app isn’t perfect though. Some external monitors have preferences that prevent the changes you made from having an effect. Also, if you use multiple monitors, you may wish to try another solution. You can use ExternalDisplayBrightness to control only one external display.

macbook external display

Control the Brightness on Your External Display with the Lunar App

If you’d like to avoid tapping buttons on your monitor, you can control your preferences with Lunar. Lunar is a free app for Mac, designed to synchronize the settings on all your displays. The only requirement is that your external device supports the Data Display Channel (DDC) protocol. If it supports it, you can install the Lunar app and start regulating brightness and other preferences of your monitor straight from your MacBook.

After you’ve to downloaded and installed Lunar, choose one of its modes:

  1. The Sync Mode lets you synchronize the built-in display preferences to the external monitor. If you’re an advanced user, you can configure the curve algorithm yourself.
  2. The Location Mode automatizes the process. If you choose it, the brightness of your monitor will adjust to the time of the day.
  3. The Manual Mode, if selected, disables the adaptive algorithm and allows you to control your monitor by using the Lunar UI or custom hotkeys.

Use F.lux to Adjust the Colors on Your External Monitor

F.lux is another free app that lets you control the brightness of your external display, albeit to a limited extent. It can be used alone or combined with another app, such as Lunar.

While installing F.lux, set preferences, enter your location and your wake time. This information will serve to generate a lighting schedule that you can edit later from the f.lux menu, which is located next to the clock. From there, you can also choose among these presets:

  1. Recommended colors: the default color preferences set by the app creators.
  2. Custom colors: you can set the time of day when you’d like the color temperature to change.
  3. Classic f.lux: f.lux will fade at sunset, and deactivate at sunrise.

If you don’t change the preferences, f.lux will use your location to determine daylight time.

Adjusting Screen Brightness on Your MacBook

If you’re using Lunar or some other app that allows you to synch the preferences of your displays, here’s how to control these settings on MacBook. Note that MacBooks are designed to manage the brightness automatically. You can, however, disable this feature and set the brightness manually.

To adjust brightness manually:

  1. Find the preset hotkeys on your keyboard. On a MacBook, those are the F1 and F2 keys, located at the top-left corner.
  2. You can do the same by using the F14 and F15 keys. If you press one of them, the brightness will decrease, and the other will make the brightness increase.
  3. You can also use your mouse to adjust the brightness. From the Apple menu, choose System Preferences>Displays>Brightness, and set the desired brightness level.

You can also set your display to dim when you’re on battery power:

  1. Go to System Preferences and select Energy Saver.
  2. Under the Battery tab, find the checkbox that says “Slightly dim the display while on battery power” and enable it.
  3. If you don’t like this preference, just uncheck it. Keep in mind that screen brightness affects your battery life.

While you can’t define the brightness levels precisely as you can on Windows, you can adjust it to a level that suits you. Only the brightness might be a bit dimmer than you’d like.

MacBooks have sensors that detect the ambient light. If you’d like to make use of this option, follow these steps:

  1. Go to System Preferences and select Displays.
  2. Find “Automatically adjust brightness” and tick it.

The Bright Way to Control Brightness

While it may seem unnecessary to spend time adjusting your external display’s preferences, a couple of minutes of extra work may level up the quality of your screen time.

Have you had to adjust the brightness on an external monitor? Did you use one of the apps from our list? Let us know your thoughts and experiences in the comments section below.

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