Format a drive using Disk Utility on a Mac. Launch Disk Utility (Applications > Utilities). Select your external hard drive or USB flash drive from the list on the left. Click on the Erase tab. Select the format – Mac OS Extended (HFS+), MS-DOS (FAT32), or exFAT – then name the drive. To format a hard drive for Windows, open the File Explorer and click on This PC. If the hard drive you want to format is connected to your PC, it should be there. Right-click on it and select the Format option from the context menu. You’ll notice there are a few different options for Mac OS Extended. In general, you’ll want Mac OS Extended (Journaled).You can use (Journaled, Encrypted) to encrypt the entire drive. However, this will make them a tad harder to work with in Disk Utility and won’t allow other computers to access the files. Connect the drive to the Mac. Open Disk Utility. The easiest way to do that is hit CMD and the spacebar at the same time and type in Disk Utility to find the program. Possibly the best solution to using a hard drive with both Windows and Mac without the use of third-party software is creating two partitions on the drive, one for Windows and one for Mac.
This how-to shows you the steps using Disk Utility 13 in OS X 10.10 Yosemite, but the process is the same if you’re using OS X 10.9 Mavericks or 10.8 Mountain Lion. Here are the instructions using OS X 10.11 El Capitan.
Sometimes you want to wipe out all the data that’s on a hard drive or solid-state drive—erase it and start over. The best way to do this is to format the drive, which both erases the drive and prepares it for storing data by mapping out bad sectors, creating address tables for locating the data on the disk, and more.
Similarly, you may have purchased a new drive that was formatted for Windows out of the box. You'll want to reformat that drive for your Mac.
Best Hdd Format
But formatting a drive so that it can be used as your Mac’s startup drive requires a slightly different procedure than formatting it for use as a secondary drive for storing data.