Well then, which is the best format for external hard drive Mac? You can get some useful information from the following part. No matter under which circumstance you need to use an external storage device on your Mac, you may want your Mac external drive to be formatted with the best file system to make it to be recognized on your Mac and maximize the best performance. If you want to transfer your Mac data to another computer, you need to use an external hard drive.If your Mac runs out of space, you can use an external hard drive to increase the storage.If you want to back up your Mac data using Time Machine, you need to use an external hard drive to save the Time Machine backups.In many cases, you need to use an external hard drive on your Mac computer. When Do You Need to Use an External Hard Drive on Mac? Best Format for External Hard Drive Mac FAQ.How to Recover Data from an External Hard Drive on Mac?.How to Format External Hard Drive on Mac?.Which Mac File System Is the Best for an External Drive?.When Do You Need to Use an External Hard Drive on Mac?.