What an ISO file is and why you'd make one

An ISO file is a single file that contains an exact copy of everything on a disc — a CD, DVD, or Blu-ray — or everything in a folder on your computer. It's useful because you can store it, move it, back it up, or burn it to a new disc later without needing the original. ISO files are also how software companies distribute large programs: you read one file instead of inserting a disc.

You might create an ISO file to preserve a disc you own before it gets scratched, to move a folder's contents to another computer as a single package, or to create a bootable disc for installing an operating system. The file itself is just data — it doesn't run anything until you open it or burn it to a disc.

Key Takeaways

  • Windows includes a built-in tool to create ISO files from discs; Mac users need third-party software like Disk Utility or Toast.
  • Creating an ISO from a folder requires free software like ImgBurn (Windows) or Disk Utility (Mac), not Windows' built-in tools.
  • The ISO file will be as large as the disc or folder it contains, so check your available storage space first.
  • Once created, you can burn the ISO file back to a blank disc using the same tool, or mount it as a virtual disc to view its contents without burning.

Creating an ISO file from a physical disc on Windows

Windows 10 and 11 include a tool called Windows Disc Image Burner that can create ISO files from discs you already own. Insert the disc into your drive, then right-click the disc in File Explorer and select "Create disc image" or "Make a copy". Windows will ask where to save the ISO file and what to name it. Choose a location with enough free space — the ISO will be as large as the disc itself.

The process takes several minutes depending on the disc size. Once finished, you'll have a single .iso file on your computer. If you don't see the "Create disc image" option when you right-click, your version of Windows may not include this feature — in that case, use free software like ImgBurn or WinCDEmu instead.

Creating an ISO file from a physical disc on Mac

Mac's Disk Utility can create ISO files from discs. Insert the disc, open Disk Utility (in Applications > Utilities), select the disc in the left sidebar, and click "File" at the top, then "Save As". Choose a location and name for the ISO file, then select "DVD/CD Master" from the format dropdown. Click Save and wait for the process to finish.

If you prefer a different tool, Toast Titanium is paid software that many Mac users rely on for disc work, but Disk Utility is free and handles most discs without trouble. The resulting ISO file works the same way regardless of which tool you use.

Creating an ISO file from a folder on Windows

Windows doesn't include a built-in tool for this, so you'll need free software. ImgBurn is the most common choice. read it from imgburn.com, install it, then open the program and click "Create image file from files/folders" (the second option on the main menu).

Click the folder icon to browse and select the folder you want to turn into an ISO. ImgBurn will show you the total size at the bottom — this is how large your ISO file will be. Choose where to save the ISO file, give it a name, and click the large burn button to start. The process may take several minutes for large folders. When finished, you'll have a single ISO file containing everything from that folder.

Creating an ISO file from a folder on Mac

Mac's Disk Utility can create ISO files from folders, though the process is less direct than on Windows. Open Disk Utility, click "File" at the top, then "New" and "Blank Image". Choose a size large enough for your folder's contents (check the folder's size first by right-clicking it and selecting "Get Info"), then save the blank image to your desktop.

Once created, the blank image appears as a mounted disc on your desktop. Drag your folder's contents into it, then eject the disc. Open Disk Utility again, select the image file you just created, click "Image" at the top, then "Convert". Choose "DVD/CD Master" format and save it as an ISO file. This creates the final ISO from your folder.

Checking your ISO file and using it later

Once you have an ISO file, you can verify it contains what you expect by mounting it as a virtual disc. On Windows, right-click the ISO file and select "Mount" — it will appear as a drive in File Explorer. On Mac, double-click the ISO file and it mounts automatically. You can browse the contents without burning anything to disc.

To burn the ISO to a blank disc later, right-click it on Windows and select "Burn disc image", or on Mac, right-click it and select "Burn". Both systems will ask you to insert a blank disc and confirm. You can also use the same software you used to create the ISO — ImgBurn on Windows or Disk Utility on Mac — to burn it back to a physical disc.

Storage space and file size considerations

An ISO file takes up exactly as much space as the disc or folder it contains. A full DVD ISO will be around 4.7 gigabytes; a full Blu-ray ISO can be 25 gigabytes or more. Before you create an ISO, check how much free space your computer has. On Windows, right-click your drive in File Explorer and select "Properties". On Mac, click the Apple menu, select "About This Mac", then "Storage".

If you're creating an ISO from a folder, the folder's size is what matters. Right-click the folder, select "Properties" on Windows or "Get Info" on Mac, and look at the total size. Make sure your drive has at least that much free space, plus a little extra as a buffer.

Frequently Asked Questions

Can I edit an ISO file after I create it?

Not directly — ISO files are meant to be exact copies. If you need to change what's inside, mount the ISO as a virtual disc, copy the files you want to a regular folder, edit them there, then create a new ISO from the updated folder.

What's the difference between ISO and other disc image formats?

ISO is the most common and widely compatible format. Other formats like BIN, CUE, or NRG exist but are less common. For most purposes, ISO is the right choice because nearly every computer and disc-burning tool recognizes it.

Do I need a blank disc to create an ISO file?

No. Creating an ISO from a disc or folder only requires storage space on your computer. You only need a blank disc if you want to burn the ISO back to a physical disc later.

Will the ISO file work on a different computer?

Yes. You can move the ISO file to any computer and mount it or burn it to a disc there. The file itself is independent of the computer that created it.

How do I know if my ISO file is corrupted?

Try mounting it as a virtual disc and opening a few files inside. If the files open normally, the ISO is fine. If you get error messages when trying to read files, the ISO may be corrupted — try creating it again from the original source.