Partition a physical disk using Disk Utility on Mac

Apple File System (APFS) allocates disk space on demand; however, you can manually manage APFS volume allocation if required.

1. In the Disk Utility app on your Mac, choose View > Show All Devices.

2. Select an existing APFS volume in the sidebar, then click the Add Volume button .

3. Enter a name for the new APFS volume.

4. Click the Format pop-up menu, then choose a file system format.

5. If you want to manually manage APFS volume allocation, click Size Options and enter values in the fields:

   • Reserve Size: The optional reserve size ensures that the amount of storage will remain available for this volume.

   • Quota Size: The optional quota size limits how much storage the volume can allocate.

   When you’ve finished, click OK.

6. Click Add, then click Done.

1. In the Disk Utility app on your Mac, choose View > Show All Devices.

2. Select the device in the sidebar, then click the Partition button .

   Internal storage devices appear below the Internal section in the sidebar. External devices appear below the External section in the sidebar.

   When you select a volume that already has data on it, the pie chart shows a shaded area representing the amount of data on the volume and an unshaded area representing the amount of free space available for another volume. Disk Utility also reports whether the volume can be removed or resized.

   If you see a small volume with an asterisk, the partition is smaller than can be represented at the correct scale in the chart.

3. Click the Add button .

4. Click each volume in the pie chart on the left, then enter a name for it.

   For MS-DOS (FAT) and ExFAT volumes, the maximum length for the volume name is 11 characters.

5. Enter the size or drag the divider to increase or decrease the size of each volume.

   

6. For each volume, click the Format pop-up menu, then choose a file system format.

7. Click Apply, then click Partition.

   Click Show Details to view the step-by-step process of creating a new volume.

8. When Disk Utility is finished creating the volumes, click Done.

After you partition a storage device, an icon for each volume appears in both the Disk Utility sidebar and the Finder sidebar.

If you have multiple volumes formatted as Mac OS Extended, MS-DOS (FAT) or ExFAT on a device and one of them is running out of space, you may be able to enlarge it without losing any of the files on it.

To enlarge a volume, you must delete the volume that comes after it on the device, then move the end point of the volume you want to enlarge into the freed space. You can’t enlarge the last volume on a device.

1. In the Disk Utility app on your Mac, choose View > Show All Devices.

2. In the sidebar, select the device that contains the volume you want to enlarge, then click the Partition button .

3. In the pie chart on the left, select the volume you want to remove, then click the Remove button .

4. Click Apply.

   The volume is removed, reformatted, and all free space is assigned to the previous volume.

5. Click Done.