How to partition an external hard drive for Mac and Windows PC.How to make external hard drive compatible with Mac and PC without formatting.Which is the best format for external hard drive on Mac and PC?.How to format (external) hard drive for Mac and PC.How to format external hard drive for Windows PC?.How to format external hard drive for Mac?.Though the default hard disk file system (also known as format) of Windows and Mac are different, there should be some ways to format an external hard drive for Mac and PC.