How to Put a DMG on a Flash Drive to Install

USB flash drives can work with both Mac and Windows computers.
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Disk Images, or DMGs, are a common way to compress large files on Mac computers, including apps. Because these files can often be a few gigabytes in size, a USB flash drive is usually the fastest way to get the file to your Mac computer. If the file has been downloaded to a Windows PC, you will need to make sure the USB flash drive is formatted in FAT32 -- a format that both the Windows PC and the Mac computer can both read. Most USB flash drives already use this format, but if yours doesn't you can quickly format it in Windows.

1 Using a Windows PC

2 Insert the flash drive

Insert the flash drive into the USB port on a Windows PC. Wait two or three seconds for the PC to recognize the drive.

3 Go to the Windows desktop

Go to the Windows desktop, launch File Explorer from the Taskbar and select "Computer." If you are in the Windows Start screen, simply type "computer" and press "Enter" to open File Explorer on the desktop.

4 Select This PC or Computer

Select "This PC" or "Computer" from the left pane in File explorer to reveal the flash drive in the Devices With Removable Storage section.

5 Right click

Right-click the flash drive unless you are absolutely certain it can be read by both a Mac and a Windows computer. Select "Format," then click "OK." If the File System menu says "FAT32," click "Close." If it instead says "NTFS," change it to "FAT32" and click "Start." This formats the drive in FAT32 so it can be read by both a Windows and Mac computer.

6 Locate the DMG file

Locate the DMG file on your computer and drag it onto the flash drive's icon in File Explorer. When the transfer is complete, remove the flash drive from the USB port.

7 Using Another Mac

8 Insert the flash drive-2

Insert the flash drive into the USB port of a Mac computer that has the DMG file you need. Launch Finder. After a couple of seconds the drive appears in the left menu of the Finder menu. If Mac OS X doesn't recognize the flash drive, it prompts you to format it and the Disk Utility app opens. Select "ExFAT" in the Format menu of the Partition tab only if you want to use the flash drive on a Windows PC. Otherwise select "Mac OS Extended (Journaled)" if you plan to use the flash drive only with Mac computers.

9 Locate the DMG file in the Finder

Locate the DMG file in the Finder. Drag the file onto the flash drive icon in the Finder's left menu.

10 Hover the cursor

Hover the cursor over the drive's icon in the Finder and select "Unmount" when the file transfer is complete. Alternatively, drag the icon from the desktop onto the Trash icon.

11 Installing From the Flash Drive

12 Insert the flash drive-3

Insert the flash drive into the USB port of the destination Mac computer.

13 Launch Finder

Launch Finder and then double-click the flash drive's icon in the left menu of the Finder window. Drag the DMG file onto the desktop or any folder in Finder. Double-click the transferred file to launch it on the Mac.

14 Right click the DMG file

Right-click the DMG file on the USB flash drive if you don't need to use the file again and select "Move to Trash." Select "Empty Trash" from the File menu to completely remove it from the flash drive.

  • Information in this article applies to Microsoft Windows 8.1 and OS X Mavericks. It may vary slightly or significantly with other versions or products.
  • If you delete a file on a USB flash drive from a Mac computer without emptying the trash, it may still be visible and occupying storage space when you insert the drive into a Windows computer.

A published author and professional speaker, David Weedmark has advised businesses and governments on technology, media and marketing for more than 20 years. He has taught computer science at Algonquin College, has started three successful businesses, and has written hundreds of articles for newspapers and magazines throughout Canada and the United States.