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# How to Create a Disk Image in Disk Utility: Step-by-Step Guide
- URL: https://macfixly.com/create-disk-image-disk-utility/
- Published: 2026-10-07T19:40:00.000Z
- Updated: 2026-10-07T19:40:00.000Z
- Description: This guide explains how to create a disk image in Disk Utility for backing up and transferring files using macOS’s built-in tool.
- Author: Macuser
- Tags: MacOS, Disk Utility, Disk Image, Backup, File Transfer

You need to back up important files or transfer data to another Mac, but you're unsure how to package everything neatly. Creating a disk image is a reliable way to consolidate files, folders, or entire drives into a single file, making storage and sharing easier. This article guides you through how to create a disk image in Disk Utility, the built-in macOS tool, with clear, step-by-step instructions.

You'll learn how to create disk image files from scratch, capture physical disks, and make images compatible with Windows. We'll also cover how to use and open disk images once created, plus common troubleshooting tips to help you avoid and fix issues. By the end, you'll be confident managing disk images for backup, system imaging, or file transfer purposes.

## Key takeaways

- Use Disk Utility's File > New Image options to create blank or folder-based disk images.
- Select the correct image format like "read/write" or "compressed" based on your needs.
- Choose "Master Boot Record" [partition scheme](https://macfixly.com/p/8c03efe7-71b5-43bb-b4f7-34ae5dcf673b/) for Windows-compatible disk images.
- Mount disk images by double-clicking or using Disk Utility to access contained files.
- Check permissions and available disk space to troubleshoot creation errors.

## Before you start: What you need to create a disk image

Disk Utility is the built-in macOS application designed to manage disks and storage devices, including creating disk images. It serves as the main tool for making various types of disk images on your Mac, allowing you to back up files, transfer data, or create system images. Before you begin, ensure you have a Mac with Disk Utility installed, which is included on all Macs by default. You will also need a source for the disk image, such as a folder of files, an external drive, or an internal disk.

Disk images come in different types, each suited for specific purposes. A **read-only** disk image preserves the data exactly as it was when created and cannot be changed later, making it ideal for archival backups. A **compressed** disk image reduces file size by compressing data, which saves storage space but requires more time to create and access. The **sparsebundle** image type grows and shrinks dynamically as you add or remove files, making it useful for incremental backups. For example, a 1 GB folder might create a 1 GB read-only DMG, a 600 MB compressed DMG, or a sparsebundle that starts small and expands as needed.

Common disk image file formats include **DMG** and **ISO**. DMG is the standard Mac disk image format, widely supported on macOS but not always compatible with Windows. ISO images are more universal and often used for Windows or Linux disk images. If you plan to share disk images with Windows users, consider using the ISO format or creating compatible images.

People create disk images for various reasons: to back up important data safely, to transfer large amounts of files while preserving folder structures, or to create system images for recovery. Knowing the type of disk image you need and the format that matches your use case will help you make the right choices before you start creating one in Disk Utility.

## How to create a disk image file using Disk Utility

Creating a disk image file from a folder or files with Disk Utility is straightforward. This process allows you to package your data into a single, portable file that can be encrypted or compressed as needed. Follow these steps carefully to create your disk image.

1. Open **Disk Utility**. You can find it in the *Applications* folder under *Utilities*, or search for it using Spotlight.
2. In the menu bar, click **File**, then select **New Image** and choose **Image from Folder...**. A file browser window will appear.
3. Navigate to and select the folder or files you want to turn into a disk image. Click **Choose**. This action prepares your selected data for imaging.
4. In the save dialog, enter a name for your disk image and choose where to save it. Under **Image Format**, select *read/write* if you want to add files later or *compressed* for a smaller file size but no modifications. The read/write option creates a larger file but keeps it editable.
5. For encryption, choose *none* if you don’t need password protection. If you want to secure your image, pick either *128-bit AES encryption* or *256-bit AES encryption*—the latter is stronger but takes longer to create.
6. Click **Save** to start creating the disk image. A progress bar will show the status, and once finished, the disk image (.dmg) file will appear in the location you specified.
7. Verify the disk image by double-clicking it. It should mount as a new drive in Finder, showing the contents of your original folder. Check that file sizes are consistent—the disk image may be smaller if compressed.

Keep in mind that compression reduces file size but may slow down access when opening the image. Encryption adds a security layer but requires you to remember the password to access the contents. Choosing the right settings depends on your priorities for file size, security, and flexibility.

## How to create a disk image from a physical disk or drive

Creating a disk image from a physical disk or drive allows you to make an exact copy that preserves the entire structure, including hidden files and system data. This is useful for backups or system imaging. To start, open Disk Utility and select the physical disk or external drive you want to image from the sidebar.

![How to create a disk image from a physical disk or drive – how to create a disk image in Disk Utility](https://macfixly.com/content/images/2026/10/create-disk-image-disk-utility-2.webp)

Next, go to the menu bar and choose **File > New Image > Image from \[device name\]**. This option creates a disk image directly from the selected device. A dialog will appear asking you to name the image and select its location.

Choose the image format carefully. For a full backup or system image, *read-only* is best because it creates an exact, unchangeable copy. If you want to save space and don’t need to modify the image, *compressed* format reduces file size without losing data. Use *sparsebundle* if you want an image that can expand as you add files later.

After saving, Disk Utility will create the image file. It often takes a few minutes depending on the size of the source disk. When finished, verify the image by selecting it in Disk Utility and clicking **Verify** to ensure no errors occurred during creation.

For example, imaging a 16 GB [USB drive](https://macfixly.com/p/bfb69dcf-db11-4488-a744-6b44fe3d56a9/) using the read-only format typically produces a 16 GB.dmg file, while the compressed format might reduce the file to around 14 GB. Sparsebundle images start small but can grow up to the size of the original disk as data accumulates.

## How to create a Windows disk image for compatibility

Windows primarily supports disk image files in the ISO format, while macOS uses DMG files by default. To ensure your disk image works seamlessly on a Windows PC, you need to create or convert your image into an ISO. Disk Utility on Mac offers limited direct creation of ISO files, but you can convert a DMG into an ISO easily.

Creating a Windows-compatible disk image is useful when you want to share software, backups, or bootable media with Windows users. Since ISO files are widely recognized by Windows tools and installers, using this format improves interoperability and reduces compatibility issues.

1. Open Disk Utility and locate your DMG file if you already have a disk image created. You should see it listed in the sidebar or browse to it using Finder.
2. With the DMG selected, go to the menu bar and click **File > Convert**. In the dialog, set the image format to **DVD/CD master**. This creates a CDR file, which is essentially an ISO with a different extension.
3. Save the converted file to your desired location. After conversion, locate this new.cdr file in Finder.
4. Rename the file extension from **.cdr** to **.iso**. macOS will prompt you about changing the extension; confirm the change.
5. Your ISO file is now ready for use on Windows. You can test compatibility by mounting it on a Windows PC or using Windows disk imaging tools like Windows Disc Image Burner or third-party utilities.

If you prefer creating an ISO from scratch for Windows use, third-party tools like Terminal commands (using `hdiutil`) or applications such as AnyToISO can provide more direct ISO creation options. However, converting from DMG is often sufficient and straightforward.

Remember that while DMG files can be opened on Windows with special software, native ISO files are far more reliable for Windows systems. Ensuring your disk images are in ISO format eliminates common confusion and maximizes cross-platform usability.

## How to use a disk image file once created

Once you have created a disk image file, you need to mount it to access its contents. The easiest way is to simply double-click the disk image file (usually with a.dmg or.iso extension) in Finder. When the disk image mounts successfully, it appears as a new drive icon on your desktop and in the Finder sidebar under Locations.

After mounting, open the disk image by clicking its icon. You can browse, open, copy, and move files within this virtual drive just like you would with any physical disk. For example, you can drag files from the disk image to another folder on your Mac or add files to the disk image if it was created with read/write permissions.

To safely unmount or eject the disk image, drag its icon to the Trash, which changes to an Eject symbol, or click the eject button next to the disk image’s name in the Finder sidebar. This step is important to ensure no data corruption occurs.

Disk images are often used for software installation. After mounting, look for a package installer (.pkg) or application file inside the disk image and run it to install the software. Similarly, disk images can be used to restore backups by copying files or using specialized recovery tools inside the mounted image.

1. Locate your disk image file in Finder and double-click it. You should see a new drive icon appear on the desktop and in the Finder sidebar.
2. Click the mounted disk image icon to open it and view its contents. You should see files or folders inside just like any other drive.
3. Drag files from the disk image to your desired location or add files if the image allows writing. Verify the copy or addition completed successfully.
4. When finished, eject the disk image by dragging its icon to the Trash or clicking the eject button in Finder. Confirm the icon disappears from desktop and sidebar.
5. For software installation, open the mounted disk image and double-click the installer or application file to proceed with installation.

Following these steps ensures you can work efficiently with disk images for backup, transfer, or installation purposes without risking data loss.

## How to run a disk image file on Mac

Running applications or installers stored inside a disk image on your Mac involves mounting the image, locating the software, and managing any security prompts that may appear. This process lets you use the contents without permanently copying them to your drive, though copying may be preferable for frequent use.

1. **Double-click the disk image file (usually with a.dmg extension)** to mount it. You should see a new drive icon appear on your desktop or in the Finder sidebar, indicating the image is now accessible.
2. **Open the mounted disk image by clicking its icon.** Inside, locate the application or installer you want to run. For example, if you downloaded a common software installer like "ExampleApp.dmg," you will find a file named "ExampleApp Installer" or similar.
3. **Double-click the installer or application file.** When you do this, macOS may display a security prompt warning you about running software from the internet or an unidentified developer. If you trust the source, click "Open" to proceed.
4. **Follow the on-screen instructions within the installer or application.** This typically involves agreeing to terms and selecting installation preferences.
5. **Decide whether to run the software directly from the disk image or copy it to your Applications folder.** Running directly is convenient for one-time use, but copying ensures better performance and access without mounting the image every time.
6. **After finishing, eject the disk image safely.** Right-click on the mounted image icon and select "Eject" or drag it to the Trash. This prevents data corruption and frees system resources.

By following these steps, you can efficiently run software stored in disk images while managing macOS security features and maintaining good file organization.

## How to troubleshoot common issues when creating or using disk images

If Disk Utility fails to create or save a disk image, the first step is to check your available disk space. Insufficient space often triggers errors like “Could not complete the operation” or “Not enough free space.” Free up storage by deleting unnecessary files or moving data to an external drive, then try again. Additionally, verify your permissions by selecting the folder or drive in Finder, pressing Command + I to open the Info window, and ensuring you have read and write access.

![How to troubleshoot common issues when creating or using disk images – how to create a disk image in Disk Utility](https://macfixly.com/content/images/2026/10/create-disk-image-disk-utility-3.webp)

Corrupted or unreadable disk images can prevent mounting or data access. When you see error messages such as “The disk image is corrupted” or “Unable to mount,” try running First Aid on the disk image through Disk Utility. Open Disk Utility, select the image file in the sidebar, and click “First Aid.” If the repair fails, restoring from a backup or using third-party recovery tools may be necessary.

Mounting issues may also arise if the disk image format is unsupported or damaged. If double-clicking does not mount the image, drag it into Disk Utility’s sidebar and attempt to mount it manually. If this fails, check if the image was created using a format incompatible with your macOS version or hardware. Converting the image to a supported format or recreating it may help.

Compatibility problems between DMG and ISO formats are common when moving images between Mac and Windows. Remember that simply renaming a DMG to ISO does not guarantee compatibility. Use Disk Utility’s “Convert” feature to correctly change the format. If Windows still cannot read the image, create the disk image on a Windows system or use third-party conversion tools.

If Disk Utility repeatedly fails or presents complex errors, consider alternative tools like Terminal commands (hdiutil) for advanced image creation and manipulation, or third-party apps such as Carbon Copy Cloner or SuperDuper! These options may offer more robust handling of disk images, especially for complex backup or system imaging tasks.

## Frequently asked questions

### How to make a disk image?

To make a disk image, open Disk Utility from the Utilities folder in Applications. Click File > New Image and choose either "Blank Image" to create a new empty image or "Image from Folder" to create an image from existing files. Name your image, select a format like "Read/Write" for editing later, and choose encryption if needed. Finally, click Save to create the image file.

### How to make a disk image file?

You make a disk image file by selecting the source in Disk Utility and choosing to create a new image. You can create an image from a folder, a physical disk, or a blank new image. Specify the desired format such as "compressed" to save space or "read/write" if you want to add files later. Then save it with a.dmg extension at your chosen location.

### How to use disk image file?

Using a disk image file usually involves mounting it by double-clicking the.dmg file in Finder. This mounts the image as a virtual drive, letting you access its contents like a regular disk. You can copy files to and from it, run applications, or use it to restore data. When finished, eject the mounted image to unmount it safely.

### How to image a disk?

To image a disk, connect the physical drive you want to image and open Disk Utility. Select the drive from the sidebar, then choose File > New Image > Image from "\[disk name\]". Choose a destination and format, then click Save. This creates an exact disk image file of the entire drive, useful for backups or cloning.

### How to run a disc image file?

Running a disk image file on a Mac is straightforward: just double-click the.dmg or.iso file in Finder. This mounts the image as a virtual volume, allowing you to access, install, or run the software inside. If the image contains an installer, launch it from the mounted volume; when done, eject the image by clicking the eject icon next to it in Finder.

## What This Guide Does Not Cover

This guide focuses solely on using Disk Utility within macOS to create and manage disk images. It does not cover the process of creating disk images on Windows or Linux, nor does it delve into advanced imaging solutions designed for enterprise-level system deployment or network-based backups. If you require cross-platform imaging tools or need to manage large-scale system imaging, consider specialized software tailored to those environments.

Additionally, this guide does not address encryption beyond the basic options available in Disk Utility, nor does it cover scripting or automation of disk image creation. Users with advanced security requirements or who need automated workflows should explore dedicated software or command-line tools like hdiutil.

## Your Next Step

After creating your disk image with the settings that best fit your needs, the most useful next step is to verify the image's integrity. To do this, select the disk image in Disk Utility, then choose **Images > Verify** from the menu bar. This confirms the image is not corrupted and is ready for backup, transfer, or mounting. Taking this additional step helps avoid surprises later when you need to restore or access your data.

**See also:** [How to Erase a Drive in Disk Utility: A Clear Step-by-Step Guide](https://macfixly.com/p/a4d1045f-9e1d-4b4d-b576-3333ee7b7e0d/) · [How to Add an APFS Volume in Disk Utility: A Step-by-Step Guide](https://macfixly.com/p/0dd917b0-df43-4aee-ab13-402fd5426623/)