When you select the number of partitions to create, Disk Utility will divide the available space equally between them. In most cases, you won’t want all partitions to be the same size. Disk Utility provides two easy ways to change the sizes of partitions.
Set Partition Sizes
- Click the partition you wish to change.
- Enter a name for the partition in the ‘Name’ field. This name will appear on the Mac desktop and in Finder windows.
- Use the Format dropdown menu to select a format for this partition. The default format, Mac OS Extended (Journaled), is a good choice for most uses.
- Use the ‘Size’ field to set a size for the partition. The size is entered in GB (gigabytes). Press the tab or enter key on your keyboard to see a visual display of the resulting partition changes.
- You can also interactively adjust partition sizes by dragging the small indicator positioned between each partition.
- Repeat the process for each partition, so that all partitions have a name, format, and final size.
- When you’re satisfied with your partition sizes, formats, and names, click the ‘Apply’ button.
- Disk Utility will display a confirmation sheet, showing the actions it will take. Click the ‘Partition’ button to continue.
Disk Utility will take the partition information you supplied and divide the hard drive into partitions. It will also add the selected file system and name to each partition, creating volumes your Mac can use.