You can resize an APFS container and its volumes with Disk Utility without reformatting the entire drive in many cases. Back up files and identify the correct container before making changes.
APFS volumes share container space, so fixed partitions often are unnecessary.
Quick Answer
To resize an APFS volume on a Mac:
- Back up important files.
- Open Disk Utility and select View > Show All Devices.
- Identify the correct APFS volume or container.
- Open the available Partition or resize controls.
- Adjust the permitted size, quota, or reserve.
- Review every warning, then apply the change.
- Verify the result before transferring important files.
How APFS Containers and Volumes Work
An APFS drive has several layers:
- Physical disk: The physical storage device.
- APFS container: Shared storage for APFS volumes.
- APFS volume: A logical storage area visible in Finder.
- Volume group: Related macOS system and data volumes.
Unlike fixed partitions, APFS volumes share free container space. Each volume can have:
- Used space: Storage currently occupied by files and system data.
- Quota: A maximum amount of space the volume can use.
- Reserve: A minimum amount of space set aside for that volume.
A quota or reserve affects the volume, not the container’s total size.
Before changing anything, inspect the disk hierarchy in Terminal or Disk Utility.
Before You Resize an APFS Container or Volume
Back up important files
Resizing is normally nondestructive, but an interruption, disk problem, or incorrect selection can cause data loss. Create a current backup before continuing. If the drive contains irreplaceable files, keep a second backup or copy those files to another disk.
Close apps and stop active transfers
Quit apps using the volume. Avoid resizing during file transfers or backups.
Warning: Some operations can unmount a volume or restart your Mac. Unsaved work may be lost if an app closes unexpectedly.
Check available space
A container cannot be safely reduced below the space already used by its volumes. In Finder, select a volume and press Command-I to view its capacity and available space. Disk Utility may also show usage information.
Do not assume that a volume’s visible free space is the only factor. APFS snapshots and system-managed data can affect how much space is actually movable.
Confirm that you selected the correct disk
External drives often have similar names, especially if they were formatted or cloned previously. In Disk Utility, use View > Show All Devices and check the drive’s capacity and connection type before changing anything.
If the drive is formatted as exFAT, NTFS, or another non-APFS format, APFS-specific volume resizing options may not be available. The choice of format also affects compatibility with Windows and other devices; see APFS vs. exFAT: Which Format Should You Use on a Mac?.
Resize an APFS Volume in Disk Utility
This method is useful when you want to limit a volume’s use of shared container space or reserve space for it.
- Open Disk Utility. You can find it in Applications > Utilities or open it with Spotlight.
- Choose View > Show All Devices.
- In the sidebar, expand the physical drive and its APFS container.
- Select the APFS volume you want to change.
- Click Partition in the toolbar.
Disk Utility may offer different resize controls depending on the selected item.
- Enter a new value for the volume’s size, quota, or reserve if those fields are available.
- Review the space indicator and any warning messages.
- Click Apply, Partition, or Resize, depending on the dialog.
- Confirm the operation and wait for Disk Utility to finish.
Controls depend on the macOS version, startup disk and volume role.
Understanding quota and reserve values
A quota limits the maximum space a volume can use. For example, setting a 200 GB quota prevents that volume from growing beyond 200 GB, even when the container has additional free space.
A reserve sets aside minimum capacity without necessarily making it appear as used.
If you simply want volumes to share available space automatically, avoid setting unnecessary limits. A quota that is too small can cause apps or macOS services to report that the volume is full even when the container still has free space.
Resize an APFS Container
Resizing changes the shared storage pool to make space for another partition or reclaim unused capacity.
Warning: Shrinking an APFS container is more consequential than changing a volume’s quota. Every volume inside the container must fit within the reduced size. Back up the drive before proceeding.
- Open Disk Utility.
- Choose View > Show All Devices.
- Select the APFS container in the sidebar, not just one of its volumes.
- Click Partition.
- Review the storage chart and the current container size.
- Enter a smaller or larger size for the container, if Disk Utility allows the change.
- If you are creating another partition, select the unallocated space and click the add button.
- Choose the required format and enter a name for the new partition, if applicable.
- Click Apply.
- Read the confirmation carefully, then click Partition or Done.
Disk Utility may refuse to reduce the container if it cannot move data safely or if snapshots and system structures occupy space near the end of the container. Do not force the operation by deleting random volumes or changing disk identifiers.
Expanding a container
Expanding an APFS container is generally possible when unallocated space is directly adjacent to it on the physical disk. Select the container, click Partition, and increase its size if the layout allows it.
An intervening partition can prevent expansion. Disk Utility may not safely move it.
Resize the Startup Disk
Resizing the startup disk requires extra care because macOS is actively using its system and data volumes.
Before starting:
- Save all work and quit open apps.
- Disconnect unnecessary external drives.
- Confirm that your backup is current.
- Make sure the Mac has stable power.
- Do not interrupt the process if the Mac restarts or displays a progress screen.
Open Disk Utility, choose View > Show All Devices, and select the relevant APFS container or volume. If Disk Utility does not permit the change while macOS is running, start from macOS Recovery and use Disk Utility there.
To enter macOS Recovery, shut down the Mac and start it using the startup procedure appropriate for your Mac. On an Apple silicon Mac, press and hold the power button until startup options appear, then choose Options. On an Intel-based Mac, start the Mac and immediately hold Command-R until the Recovery screen appears.
From the Recovery environment:
- Choose Disk Utility.
- Select Continue.
- Choose View > Show All Devices.
- Select the correct APFS container or volume.
- Use Partition or the available resize controls.
- Apply the change and wait for it to complete.
- Quit Disk Utility and restart the Mac.
Do not erase the startup disk unless you intend to remove all data and reinstall macOS.
Use Terminal for Advanced APFS Resizing
Terminal is useful when Disk Utility does not clearly show the container layout or when you need to inspect identifiers. It should not be your first choice for an unfamiliar disk.
First, list the disk structure:
diskutil list
This displays disk, container and volume identifiers.
To view detailed APFS information, use:
diskutil apfs list
This reports capacity, free space, volume roles and identifiers without modifying disks.
Resize an APFS volume’s quota or reserve
If you know the correct APFS volume identifier, the general command is:
diskutil apfs resizeVolume IDENTIFIER limits MINIMUM MAXIMUM
Replace IDENTIFIER with the correct volume identifier. Replace MINIMUM and MAXIMUM with values such as 100g and 200g.
For example:
diskutil apfs resizeVolume disk3s1 limits 100g 200g
This sets a minimum reserve of 100 GB and a maximum quota of 200 GB for that volume. It does not automatically shrink the physical disk or APFS container.
To remove those limits, use:
diskutil apfs resizeVolume disk3s1 limits none none
Replace disk3s1 with the actual identifier from your Mac. This reversal removes the quota and reserve settings; it does not restore files deleted by another operation.
Warning: Never copy an identifier from an example and run it without checking your own diskutil apfs list output. A wrong identifier can target a different volume.
Resize an APFS container
Container resizing uses the container identifier and a new size. Because command syntax and permitted operations can vary by disk layout, first inspect the container with diskutil apfs list and use Disk Utility whenever it provides the required control.
Do not use destructive commands such as eraseDisk, apfs deleteContainer, or partitionDisk unless you have a complete backup and intentionally want to erase or recreate storage. These commands can remove volumes and their data.
Verify the Resize
After the operation finishes:
- Open Disk Utility.
- Choose View > Show All Devices.
- Select the physical disk, container, and changed volume.
- Confirm the new capacity and available space.
- Open the volume in Finder.
- Test a small file operation if it is an external drive.
For a detailed Terminal check, run:
diskutil apfs list
Compare the container size, volume limits, and available space with the values you intended to set.
If you resized an external drive, eject it in Finder and reconnect it before using it for important transfers. This can help confirm that the volume mounts correctly after the change.
Troubleshooting APFS Resize Problems
Disk Utility will not let me resize the volume
The selected item may be the wrong layer. Select the APFS volume for volume limits, or select the APFS container for container resizing. Turn on View > Show All Devices so you can see both.
The volume may also be part of a system volume group, encrypted, mounted in use, or too full to shrink. Try macOS Recovery for the startup disk.
The resize option is unavailable
The drive may use a format other than APFS, or there may be no adjacent free space. Disk Utility cannot always move partitions to create the layout required for an expansion.
Check the format and physical layout before making further changes. Do not erase the drive merely to make the option appear unless you have deliberately chosen that approach and backed up all data.
The container cannot be reduced
Free space may not be contiguous, meaning it is not gathered in a form that can be removed from the end of the container. APFS snapshots or system data may also prevent the reduction.
Run First Aid from Disk Utility after backing up, then try again from macOS Recovery if appropriate. If the operation still fails, avoid repeated attempts and consider copying the data elsewhere, erasing the drive, and recreating the desired layout.
A volume disappeared after resizing
Do not immediately initialize or erase the disk if macOS asks to do so. Check Disk Utility with Show All Devices, inspect the container with diskutil apfs list, and verify that the volume is mounted.
If files are missing, stop writing to the disk. Further writes can overwrite recoverable data. For recovery guidance, see how to recover deleted files from an external drive on a Mac.
The external drive keeps disconnecting
Unexpected disconnections during a resize can interrupt the process and damage the file system. Check the cable, adapter, hub, and power source, and connect the drive directly to the Mac when possible.
If the drive disconnects during ordinary use, resolve that problem before attempting another resize. Repeated disconnections can also complicate repairs and backups.
Frequently Asked Questions
Can I resize an APFS volume without erasing it?
Often, yes. Disk Utility can usually change APFS volume limits without erasing the volume. Container reductions and changes to unusual layouts have more restrictions.
Will resizing delete my files?
A normal supported resize is designed to preserve data, but no storage operation is risk-free.
Should I use Disk Utility or Terminal?
Use Disk Utility for most tasks. Use Terminal to inspect identifiers and volume details or to change APFS limits when you understand the command and have verified the target volume.
Final Thoughts
Disk Utility is the safest starting point for resizing APFS storage on a Mac.