You must select the drive name as a correct way to format the disk. Even if you select the Volume, it will also format the Disk, because there is no other Volume on this disk as shown in the picture. Select the External drive or Flash Drive on the left that shows the capacity and not the Volume which appears indented below the drive.Connect the External disk drive or Flash Drive and open Disk Utility.app from /Applications/Utilities/ folder.Format an External Disk or a Flash Drive for Mac using Disk Utility in OS X El Capitan and macOS Siera. You could either use Disk Utility or Terminal command to format it for Mac. Please be aware that formatting a drive will erase it completely, so make sure you have backed up any important data you want to keep in case you are not using a brand new external hard drive.There are two ways to format an external disk or a flash drive for Mac. How to Format an External Disk or a Flash Drive for Mac? You must format the external disk or flash drive in Mac OS Extended ( Journaled) with GUID partition table, If you want to make it a bootable USB installer disk for OS X.If you want to use the drive for Time Machine backup, it must be formatted in Mac OS Extended ( journaled).

If you want to create an encrypted drive for Mac, it should be formatted in Mac OS Extended (Journaled).So if you wish to clean a hard drive for a fresh install of OS X you will need to format it under Mac OS Extended ( Journaled). Mac OS X can only be installed on a hard drive formatted in Mac OS Extended ( Journaled), filesystem.Here are the following most common reasons why would you like to format an external disk or a flash drive for Mac under Mac OS Extended ( Journaled). There are a good number of reasons why you might want to format an external disk or a flash drive for full Mac compatibility.

5 Format an External Disk or a Flash Drive for Mac using Terminal Command Why would you format an External Disk or a Flash Drive in Mac OS Extended (Journaled)?.

4 Format an External Disk or a Flash Drive for Mac using Disk Utility in OS X Mavericks and below versions.

3 Format an External Disk or a Flash Drive for Mac using Disk Utility in OS X El Capitan and macOS Siera.

2 How to Format an External Disk or a Flash Drive for Mac?.

1 Why would you format an External Disk or a Flash Drive in Mac OS Extended (Journaled)?.

Format flash drive to ntfs on mac