connect monitor to macbook pro

Using a macbook external monitor with lid closed

Updated 11/27/2018: You can easily use the MacBook, MacBook Air, or MacBook Pro in what's commonly called clamshell mode. Clamshell mode is when the laptop lid is closed but the machine is hooked up to an external monitor, keyboard, and mouse, effectively turning your portable Mac into a desktop.

Doing this is easy, we'll cover two different ways for how to get a Mac laptop into clamshell mode, one on system boot, and the other when waking from sleep.

How to Activate Clamshell Mode with Mac On System Boot

You can boot a Mac laptop directly into clamshell mode if desired, here's how:

Connect your external keyboard, mouse, power supply, and display to the MacBook, MacBook Pro, or MacBook Air
Boot your MacBook and once you see the Apple logo, close the machines lid
Mac OS X will now continue to boot using the external monitor as it's main display, and with your laptop closed in "clamshell mode"

That's it, as long as you have an external keyboard, mouse, and of course an external screen to use the Mac, you'll continue to use the Mac laptop in clamshell mode.

How to Use Clamshell Mode When Waking Mac from Sleep

You can place a Mac laptop into clamshell mode at anytime by using the sleep mechanism, here's how that works:

Be sure the external keyboard, mouse, power supply, and external display are hooked up to the MacBook, MacBook Air, or MacBook Pro
Put the machine to sleep and close the lid
Keeping the lid closed, hit any key on the external keyboard to wake the MacBook/Pro from sleep
The Mac will now use the external display as the primary monitor, keeping the laptop in clamshell mode

Whichever method you use to enter into clamshell mode, the Mac laptop will run that way with the lid closed.

Clamshell Mode with MacBook Air

Clamshell mode works with any modern Mac laptop, including the MacBook Pro, MacBook Air, and MacBook, and in basically every version of MacOS and Mac OS X, including MacOS Mojave 10.14, High Sierra, macOS X El Capitan, MacOS Sierra, Mac OS X Yosemite, Mac OS X Mavericks, Mac OS X 10.7, Mac OS X 10.6.8, and even earlier versions too.

How to Exit Clamshell Mode on MacBook Pro, Air?

You can exit clamshell mode anytime simply by lifting the lid on the Mac laptop. Once the lid is no longer closed, the internal MacBook / Air / Pro screen should turn itself back on.

The screens may flash briefly as the monitors adjust to the new setting of exiting clamshell mode, and that is normal behavior.

Important notes on running a MacBook or MacBook Pro with the lid closed in clamshell mode:

You may notice the fans on your Mac laptop running more often when the computer is operating with the lid closed in clamshell mode.

Both the MacBook and MacBook Pro use the keyboard as a way to aid in the dissipation of heat, thus keeping the machine in clamshell mode may reduce the cooling efficiency of the Mac laptop. Therefore it is important to be sure that the MacBook / Air / Pro has adequate ventilation otherwise.

Perhaps the ideal situation of running a Mac with the lid closed is to use a laptop stand or something similar that increases the airflow around the machine while the computer is in clamshell mode. Insuring adequate airflow will reduce the likelihood of the machine overheating, which can lead to all sorts of issues including slowdowns, crashing, or even hardware problems. Remember, heat is not good for electronics, so you'll want to allow that heat to dissipate.

Personally, I like to keep my MacBook Pro's screen open so I can benefit from the increased productivity of dual monitors, I just turn the larger external display into my primary screen.

External Thunderbolt Display and MacBook Pro in clamshell mode