How to Format External Hard Drive on a Mac
Step 1. To format external drive on mac firstly connect the hard drive to the Mac.
Step 2. Go to spotlight search and search for “Disk Utility”
Step 3. Now open Disk Utility. A new window will open
Step 4. Locate your external hard drive on the left hand side of the window.
Step 5. Choose the drive and click on Erase icon on the centre of the disk utility window.
Step 6. Choose the format Mac OS Extended ( Journaled)
Step 7. Mac will start erasing data. In this way you can format hard drive on Mac.