Quick Answer
To restore a disk image to a drive using Disk Utility:
- Connect the destination drive to your Mac. 2. Open Disk Utility from Applications > Utilities. 3. Select View > Show All Devices. 4. Select the destination volume or physical drive in the sidebar. 5. Click Restore. 6.
What Does Restoring a Disk Image Do?
A disk image is a file that contains the data and structure of a disk or volume. Common disk-image formats include .dmg, .img, and some other formats created by backup or cloning tools.
Restoring an image is different from copying the image file to a drive. Disk Utility reads the image and writes its contents directly to the destination. Depending on the image, the result may include:
- Files and folders
- A bootable macOS volume
- Partitions
- File-system information
- Recovery or installation data
This makes restoration useful for creating a bootable installer, duplicating a prepared drive, recovering a volume from an image, or deploying the same disk layout to another drive.
The destination drive must usually be at least as large as the data or layout stored in the image. If the image contains multiple partitions, Disk Utility may need enough space for the entire layout, not just the visible files.
Before You Restore an Image
Restoring is destructive. It can erase the destination volume or the entire physical drive, depending on what you select and how the image was created.
Before opening Disk Utility:
- Back up important data on the destination drive. Restoration can permanently remove existing files.
- Disconnect other external drives if possible. Leaving only the intended source and destination connected reduces the chance of selecting the wrong disk.
- Keep the Mac connected to power. Do not allow a Mac notebook to shut down during the process.
- Close apps using the destination drive. Files that are open or actively being changed may prevent the restore from starting.
- Check the image file. Make sure it finished downloading or copying and is stored somewhere your Mac can access.
- Confirm the destination’s size. It should have enough capacity for the image contents.
If the destination is not visible in Disk Utility, learn how to fix a startup disk or drive that is not showing on Mac.
Restore a Disk Image to a Drive in Disk Utility
1. Connect the destination drive
Connect the drive that will receive the image. This might be an external SSD, a USB flash drive, an SD card, or another supported storage device.
If the image is also stored on an external drive, connect that drive as well. Avoid using a drive as both the image source and the destination unless you have already copied the image elsewhere. Restoring to it could overwrite the image before the operation finishes.
2. Open Disk Utility
Open Finder, select Applications in the sidebar, open the Utilities folder, and then double-click Disk Utility.
You can also press Command-Space, type Disk Utility, and press Return.
3. Show the complete device hierarchy
In the Disk Utility menu bar, select View > Show All Devices.
This displays physical drives, containers, and volumes in a hierarchy. A physical drive is the actual hardware. A volume is a formatted storage area that appears in Finder. Selecting the wrong level can change what Disk Utility restores or erases.
For most full-drive images, select the physical destination drive—the top-level item for that device. For an image intended for one existing volume, select the appropriate volume instead.
Read the name and capacity carefully. Do not rely only on the drive’s position in the sidebar.
4. Select the destination
Click the destination drive or volume in the Disk Utility sidebar.
Confirm that:
- It is the correct external drive or volume.
- Its capacity matches the drive you intend to overwrite.
- It does not contain files you still need.
- It is not your current startup disk unless you are working from macOS Recovery or another startup system.
If the destination is mounted and contains open files, close those files first. Disk Utility may unmount the destination during restoration, which can close apps or interrupt access to the drive.
5. Click Restore
With the destination selected, click Restore in the Disk Utility toolbar.
If the button is unavailable, you may have selected a volume or device that cannot accept the chosen image, or the drive may be in use. Check the selection and close apps that are accessing it.
Disk Utility opens a restore dialog. The selected item should appear as the destination.
6. Choose the disk image
Click the Restore from pop-up menu, then choose the image file if it appears in the list.
If it does not appear:
- Choose the option to select an image file, if available.
- Browse to the location of the
.dmg,.img, or supported image file. - Select the file.
- Click Choose or the equivalent confirmation button.
Check the source and destination carefully. The image should be the source, and the external drive or volume should be the destination.
7. Confirm the warning
Disk Utility displays a warning that restoring will erase the destination. Read it carefully.
This is the final point to stop if you selected the wrong disk or still need files from it. Click Restore only after confirming that the destination can be erased.
You may need to enter an administrator password or authenticate with Touch ID.
8. Wait for the restore to finish
Disk Utility shows progress while it writes the image. The time required depends on the image size, the speed of the source and destination, and the connection between the drive and Mac.
Do not:
- Disconnect either drive
- Close Disk Utility
- Put the Mac to sleep
- Restart or shut down the Mac
- Use the destination for other tasks
When the process finishes, Disk Utility reports that the restore is complete. The destination may be unmounted and remounted, or it may appear under a different volume name.
9. Verify the restored drive
After completion, open Finder and check the restored volume. Confirm that expected files, folders, and volumes are present.
If the image was intended to create bootable media, do not assume that every Mac can start from it. Bootability depends on the image, the destination’s partition scheme and format, the Mac’s hardware, and the version of macOS associated with the image.
You can also select the restored volume in Disk Utility and run First Aid to check its file-system structure. For a separate explanation of that process, see how to repair a Mac disk with First Aid.
Restore an Image from macOS Recovery
If you need to restore an image to a Mac’s internal startup disk, the normal macOS environment may not allow the operation because that disk is in use. In that situation, start the Mac from macOS Recovery or another usable startup volume, then open Disk Utility there.
The exact startup procedure depends on whether the Mac uses Apple silicon or an Intel processor. Once Recovery starts:
- Open Disk Utility from the Recovery utilities window.
- Select View > Show All Devices.
- Select the internal destination drive or the appropriate volume.
- Click Restore.
- Choose the disk image as the source.
- Review the erase warning and confirm the operation.
Restoring to the internal startup disk can remove macOS, personal files, applications, and recovery data currently stored there. Make sure you have a reliable backup and a way to reinstall or start macOS afterward.
If the image is stored on an external drive, connect it after macOS Recovery loads. Some external devices may not work correctly through an adapter or hub, so connect the source drive directly to the Mac when practical.
If the Restore Button Is Missing or Unavailable
Several conditions can prevent restoration:
- The selected item is not a suitable destination.
- The destination is locked, read-only, or currently in use.
- The image format is not supported by Disk Utility.
- The source image is damaged or incomplete.
- The drive has a hardware or connection problem.
- The Mac is running from the disk you are trying to overwrite.
Select View > Show All Devices and choose the correct physical drive or volume. If the drive is mounted, try ejecting it in Finder or Disk Utility before restoring. Do not eject a drive that contains the image source unless you have another copy of the image available.
You can also try disconnecting and reconnecting the destination, using a different cable or port, and restarting Disk Utility.
Troubleshooting Disk Image Restoration
Disk Utility says the image cannot be opened
The image may be incomplete, damaged, or in a format Disk Utility does not support. Check the file extension and its size. If the image was downloaded, download it again from the original source. Avoid renaming a file extension as a substitute for converting the file; changing the name does not change the image format.
The destination is too small
A drive can have enough free space for the visible files but still be too small for the image’s partition layout. Use a destination with greater capacity. Also remember that advertised drive capacity and the capacity shown by macOS may differ slightly.
The restore stops with an error
First, check the cable, adapter, and power connection. If the image is on another external drive, verify that both drives remain connected. Try copying the image to the Mac’s internal storage before restoring, provided there is enough free space.
If the destination may be failing, run First Aid or test the drive with the manufacturer’s utility. First Aid cannot repair every hardware problem, so repeated errors or disconnections may indicate that the drive should be replaced.
The restored drive does not appear in Finder
Open Disk Utility and see whether the volume is listed. If it is listed but not mounted, select it and click Mount. If the drive is not visible at all, reconnect it and check View > Show All Devices. For additional mounting guidance, see how to mount and unmount a disk in Disk Utility on Mac.
The drive appears, but the files are missing
Make sure you restored the intended image and selected the correct destination. Some images contain a single volume, while others contain several partitions. Check the full device hierarchy in Disk Utility and look for additional volumes.
If the image was a backup created by specialized software, it may need that software to restore or browse its contents. A generic disk image is not necessarily a complete backup of every Mac setting or user account.
The restored drive will not boot
A restored image is not automatically bootable. The image must contain a bootable system, and the destination must use a compatible partition scheme and file system. The Mac may also require a compatible startup system or security setting.
If the drive is intended as a macOS installer, create it using a method designed for macOS installation rather than assuming any .dmg file is an installer. If it is a clone, verify that the image was created for the type of Mac and startup process you plan to use.
The restore erased the wrong drive
Stop using the affected drive immediately to avoid overwriting potentially recoverable data. Do not restore another image to it, create new files, or reformat it. Professional data-recovery assistance may be necessary, and recovery is not guaranteed.
This is why disconnecting unrelated drives and checking the destination’s name and capacity before clicking Restore is so important.
Frequently Asked Questions
Does restoring a disk image erase the destination?
Usually, yes. Disk Utility generally replaces the destination’s contents with the contents of the image. Treat the destination as if it will be completely erased, even if the image contains less data than the drive.
Can I restore a .dmg file to a USB drive?
Sometimes. A .dmg file can contain files, an installer, or a complete disk image.
Can I restore an image to a smaller drive?
Usually not if the image includes a disk layout or data that exceeds the destination’s capacity. Even if the image contains relatively little free space, its structure may require a drive at least as large as the original.
Can I use my Mac while Disk Utility restores the image?
You can use the Mac for unrelated tasks, but it is safer to avoid intensive work and not use either the source or destination drive. Never disconnect the drives, restart the Mac, or allow it to shut down during the restore.
What is the difference between restoring and copying an image file?
Copying an image file places the file itself on a drive. Restoring an image writes the image’s contents to the destination, potentially creating its files, volumes, partitions, and boot information.
Should I select the drive or the volume?
Select the physical drive for a full-drive image or an image that contains partition information. Select a volume only when the image is intended for that specific volume. If you are unsure, stop before restoring and verify the image’s documentation.
Final Thoughts
Disk Utility can restore a disk image directly to an external drive or another suitable destination, but the operation is destructive.