How can I turn off the screen on the macbook when I have an external monitor set up?

I have an external monitor and want my macbook screen to go blank or black so I can focus on the monitor instead. On my windows machine Function F5 does this.

Solution 1:

Hold down the decrease screen brightness button at the top of the keyboard, it will get dimmer and dimmer, and at the end jump to a black screen (the screen's light will actually be off). To turn the screen back just press the increase screen brightness button.

Solution 2:

Turn on your MacBook without the external display connected.

Close the lid and it will go to sleep.

Connect your external monitor and an external keyboard via USB.

Now wake it up by typing on the external keyboard. If you don't have a USB keyboard (you might be using a BT keyboard and mouse) you can use the Apple Remote to wake up a MacBook when its lid is closed.

The MacBook should wake up with the external monitor as its one and only monitor.

Solution 3:

There doesn't seem to be an out-of-box way to do it in Mac OS, but with this third-party plugin https://github.com/Eun/DisableMonitor does the trick! Just download and run the app form the button in the readme shown, and an icon will show in the menu bar like just like Airplay does, and from it you pick the monitor or monitors shown and whether the Disable it.