Or as the macOS Catalina is out, chances are you’ve lots of Mac and would like to create macOS Catalina bootable USB installer on Windows. For installing most systems like Windows 10 and others, creating a bootable USB installer is the first step and also the most important step.

When OS X shipped on a DVD a good number of years ago, you always had the convenience of a bootable installer—an OS X installer that could be used to boot your Mac if its own drive was having problems. But to install or reinstall a recent version of OS X, you must either download a non-bootable installer from the Mac App Store or (via OS X’s invisible, bootable recovery partition) download 6GB of installer data from Apple’s servers during the installation process. In other words, you no longer have the same safety net or convenience.

• Install Disk Creator is a straightforward way to create a boot disk. I was able to make a macOS Sierra external USB boot disk in a few minutes, and the installation worked without a hitch.
• Plug the bootable installer into a Mac that is connected to the internet and compatible with the version of macOS you're installing. Press and hold the Option (Alt) ⌥ key immediately after turning on or restarting your Mac. Release the Option key when you see a dark screen showing your bootable volumes.

Because of this, I recommend creating your own bootable El Capitan (OS X 10.11) installer drive on an external hard drive or USB thumb drive. If you need to install El Capitan on multiple Macs, using a bootable installer drive is faster and more convenient than downloading or copying the entire installer to each computer. If you want to erase the drive on a Mac before installing El Capitan, or start over at any time, you can use a dedicated installer drive to boot that Mac, erase its drive, and then install the OS (and subsequently restore whatever data you need from your backups). And if your Mac is experiencing problems, a bootable installer drive makes a handy emergency disk.

(OS X Recovery lets you repair your drive and reinstall OS X, but to perform the latter task, you must wait—each time you use it—for the entire 6GB of installer data to download. At best, that’s a hassle; at worst, it’s hours of waiting before you can get started.)

As with previous versions of OS X, it’s not difficult to create a bootable installer drive, but it’s not obvious, either. I show you how, below.

Keep the installer safe

Like all recent versions of OS X, El Capitan is distributed through the Mac App Store: You download an installer app (called Install OS X El Capitan.app) to your Applications folder. In this respect, the OS X installer is just like any other app you buy from the Mac App Store. However, unlike any other app, if you run the OS X installer from that default location, the app deletes itself after it’s done installing OS X.

If you plan to use the OS X installer on other Macs, or—in this case—to create a bootable installer drive, be sure to copy the installer to another drive, or at least move it out of the Applications folder, before you use it to install the OS on your Mac. If you don’t, you’ll have to redownload the installer from the Mac App Store before you can use the instructions below.

What you need

To create a bootable El Capitan installer drive, you need the El Capitan installer from the Mac App Store and a Mac-formatted drive that’s big enough to hold the installer and all its data. This can be a hard drive, a solid-state drive (SSD), a thumb drive, or a USB stick—an 8GB thumb drive is perfect. Your drive must be formatted as a Mac OS Extended (Journaled) volume with a GUID Partition Table. (Follow this tutorial to properly format the drive if you’re using OS X Yosemite or older. If you’re using OS X El Capitan, use these instructions.)

Your OS X user account must also have administrator privileges.

Apple’s gift: createinstallmedia

In my articles on creating a bootable installer drive for older versions of OS X, I provided three, or even four, different ways to perform the procedure, depending on which version of OS X you were running, your comfort level with Terminal, and other factors. That approach made sense in the past, but a number of the reasons for it no longer apply, so this year I’m limiting the instructions to a single method: using OS X’s own createinstallmedia tool.

Starting with Mavericks, the OS X installer hosts a hidden Unix program called createinstallmedia specifically for creating a bootable installer drive. Using it requires the use of Terminal, but createinstallmedia works well, it’s official, and performing the procedure requires little more than copying and pasting.

The only real drawback to createinstallmedia is that it doesn’t work under OS X 10.6 Snow Leopard—it requires OS X 10.7 Lion or later. Though it’s true that some Macs still running Snow Leopard can upgrade to El Capitan, I think it’s safe to assume that most people installing OS X 10.11 will have access to a Mac running 10.7 or later.

(If you absolutely refuse to go near Terminal, an El Capitan-compatible version of DiskMaker X is now available, although I haven’t yet had the chance to test it.)

Making the installer drive

1. Connect to your Mac a properly formatted 8GB (or larger) drive, and rename the drive Untitled. (The Terminal commands I provide here assume that the drive is named Untitled. If the drive isn’t named Untitled, the procedure won’t work.)
2. Make sure the El Capitan installer (or at least a copy of it), called Install OS X El Capitan.app, is in its default location in your main Applications folder (/Applications).
3. Select the text of the following Terminal command and copy it. Note that the window that displays the command scrolls to the right.
4. Launch Terminal (in /Applications/Utilities).
5. Warning: This step will erase the destination drive or partition, so make sure that it doesn’t contain any valuable data. Paste the copied command into Terminal and press Return.
6. Type your admin-level account password when prompted, and then press Return.
7. You may see the message “To continue we need to erase the disk at /Volumes/Untitled. If you wish to continue type (Y) then press return:” If so, type the letter Y and then press Return. If you don’t see this message, you’re already set.

The Terminal window displays createinstallmedia’s progress as a textual representation of a progress bar: Erasing Disk: 0%… 10 percent…20 percent… and so on. You also see a list of the program’s tasks as they occur: Copying installer files to disk…Copy complete.Making disk bootable…Copying boot files…Copy complete. The procedure can take as little as a couple minutes, or as long as 20 to 30 minutes, depending on how fast your Mac can copy data to the destination drive. Once you see Copy Complete. Done., as shown in the screenshot above, the process has finished.

Createinstallmedia will have renamed your drive from Untitled to Install OS X El Capitan. You can rename the drive (in the Finder) if you like—renaming it won’t prevent it from working properly.

Booting from the installer drive

You can boot any El Capitan-compatible Mac from your new installer drive. First, connect the drive to your Mac. Then, restart your Mac (or, if it’s currently shut down, start it up) while holding down the Option key. When OS X’s Startup Manager appears, select the installer drive and then click the arrow below it to proceed with startup. (Alternatively, if your Mac is already booted into OS X, you may be able to choose the installer drive in the Startup Disk pane of System Preferences, and then click restart. However, sometimes OS X installer drives don’t appear in the Startup Disk window.)

Once booted from your installer drive, you can perform any of the tasks available from the OS X installer’s special recovery and restore features. In fact, you’ll see the same OS X Utilities screen you get when you boot into OS X Recovery—but unlike with recovery mode, your bootable installer includes the entire installer.

Apple uses its App Store to distribute its software, like new Mac operating systems. It’s convenient, but sometimes it can take a while for a download to finish. And if you have multiple Macs, it’s inefficient to download the new OS to each and every Mac.

That’s why I like to make a bootable external drive for the sole purpose of installing the Mac operating system. When I need to tend to a bunch of Macs, it’s much faster to use a bootable drive instead of going to each Mac, launching the App Store, searching for the operating system, downloading it (after entering my Apple ID), and then running the installer.

You can create a bootable USB flash drive with the macOS Sierra installer that’s now available. The installer software will take up nearly 5GB of storage space. Here’s how to create a bootable macOS Sierra installer drive.

Download the macOS Sierra installer

Launch the App Store app, then look for macOS Sierra in the store. (Here’s a link.) Click on the Download button, and your Mac will download the installer to your Applications folder. If it automatically launches after download, quit the installer.

If you’ve already upgraded your Mac to Sierra, the installer is removed from the Applications folder. You can download it again if you go to Purchased in the App Store. Look for macOS Sierra in the list of apps that you’ve bought, and click on the Download button. If it automatically launches after download, quit the installer.

Get an external drive

You can use a USB flash drive or a hard drive with room for the installer software. I’ve used different drives with success, including a VisionTek 120GB USB 3.0 Pocket Solid State Drive ($83 on Amazon) and an old 8GB Iomega Micro Mini Hard Drive.

How To Create A Bootable Installer For Mac

Don’t worry if the drive isn’t formatted for the Mac. The drive will be reformatted automatically as part of the process. Change the name of your drive to Untitled; you need to do this for the steps below.

The quick and easy way

The process detailed below involves the Terminal. If your really don’t want to use Terminal, there are a couple of free apps you can use.

• Install Disk Creator is a straightforward way to create a boot disk. I was able to make a macOS Sierra external USB boot disk in a few minutes, and the installation worked without a hitch. Also works with older versions of OS X.
• Diskmaker X is a popular app. It also supports older versions of OS X.

Use the Terminal to create a boot disk

So you have your external drive, and the Sierra beta installer is in place. Now you’re going to use Terminal to create a boot drive. If you’ve never used Terminal before, don’t worry. This is pretty easy.

What Is A Bootable Installer For Mac

Here are the steps to create a macOS Sierra beta boot disk. (Apple also has these instructions.)

1. Connect the external drive to your Mac. (In the Terminal command you will use, I use Untitled to represent your external drive. If your drive is named something else, you need to change Untitled to the name of your drive.)
2. Launch Terminal (/Applications/Utilities/Terminal.app).
3. Copy the following:
   sudo /Applications/Install macOS Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/Untitled --applicationpath /Applications/Install macOS Sierra.app
4. Go back to Terminal and paste the copied code at the prompt.
5. Terminal will ask for a password. This is your user password. Terminal doesn’t display characters when you type it in. Hit Return.
6. Terminal will tell you that it will erase your drive. To confirm that you want to continue, type Y and hit Return.
7. You’ll see that Terminal erases your drive. When that part is done, your Mac may ask you if you want to use the drive for Time Machine. Click Don’t Use.
8. Terminal will copy the installer file to your drive. This will take a few minutes.
9. After copying, Terminal is done. You should see Terminal display a “Copy complete” and Done notice. You can quit Terminal and your drive is ready for use.

How To Make A Bootable Installer For Mac

How to boot from the installer drive

Bootable Installer For Macos On Windows

1. Plug your external drive into your Mac.
2. Power up (or restart) your Mac. Press down on the Option key while the Mac boots.
3. After a few moments, your Mac should display the Startup Manager, which will show you the available boot drives. Click on the external drive and hit Return. (You don’t need to select a network to proceed.)
4. Your Mac will display an OS X Utilites window. If you want to install Sierra and leave the data intact, select Install OS X. If you want to start over and wipe out the data, you need to go into Disk Utility to reformat the internal drive first, and then install macOS Sierra.