How to Open an ISO File: Mount or Extract

What is an ISO file?

An .iso file is a byte-for-byte, sector-by-sector image of an entire optical disc — a CD, DVD or Blu-ray — packaged into a single file. The name comes from ISO 9660, the international standard (published by ISO, and equivalently by Ecma International as ECMA-119) that defines the filesystem almost every disc image uses internally.

Structurally, an ISO 9660 image reserves its first 32,768 bytes as a "system area" (historically for boot code), followed by a Volume Descriptor Set starting at sector 16. The Primary Volume Descriptor there declares the disc's volume label, total size, and — critically — the location of the root directory, whose own directory records point to every file and subfolder on the disc, each with its own location and size. This page's tool reads all of that directly, the same structures any operating system's own mount logic reads.

Many discs also carry a Joliet extension (a second volume descriptor enabling long Unicode filenames, common on Windows-authored discs) or Rock Ridge extensions (for Unix permissions and long names). This page's tool detects whether Joliet is present and reads the base ISO 9660 tree either way.

Is it safe to open an ISO file?

Reading or mounting an ISO's filesystem structures — exactly what this page's tool and your operating system's native "mount" feature both do — carries no risk by itself; it's just reading a directory listing. The real question, as with any download, is what's actually inside the disc image and how much you trust the source you got it from.

How to mount or burn an ISO file

1. Windows 8 and later: Right-click the .iso and choose "Mount", or just double-click it — it appears instantly as a new drive letter in File Explorer.
2. macOS: Double-click the .iso; Disk Utility mounts it automatically as a virtual disc on the Desktop.
3. Linux: Most desktop file managers mount an ISO on double-click; from a terminal, mount -o loop image.iso /mnt/iso does the same thing manually.
4. To burn it to a physical disc instead (only needed for booting very old hardware or making a physical copy), use your OS's built-in disc-burning feature, or free tools like Rufus (for bootable USB) or ImgBurn (Windows disc burning).

Make a bootable USB from an ISO (Rufus, Etcher, Ventoy)

To install or repair an operating system from an ISO on a PC without a DVD drive, write it to a USB flash drive with a tool that makes the stick bootable. Everything on the USB drive will be erased.

Windows: Rufus

1. Plug in a USB drive of at least 8 GB and download Rufus from its official site.
2. Run Rufus and pick the USB stick under Device.
3. Under Boot selection, click SELECT and choose your .iso.
4. Leave Partition scheme on GPT for any PC from the last decade (UEFI); choose MBR only for old BIOS-only machines.
5. Click START. For a Windows 11 ISO, Rufus may offer optional tweaks (such as removing hardware checks or the online-account requirement) — leave them unticked for a standard install. Confirm the warning that the drive will be erased.

Other options

• Windows 10/11 from Microsoft: Microsoft's own Media Creation Tool downloads Windows and creates the USB in one go, without you handling the ISO at all.
• Linux ISOs on Windows, Mac or Linux: balenaEtcher is the simplest — Flash from file, Select target, Flash!. It writes the image byte-for-byte, which is what Ubuntu, Fedora, Mint and most other distributions expect.
• Several ISOs on one stick: Ventoy installs a small boot loader once; afterwards you just copy .iso files onto the USB drive and choose one from a menu at boot.

Open an ISO on Mac

1. Double-click the .iso. macOS mounts it with its built-in DiskImageMounter and shows the disc on the desktop and in the Finder sidebar.
2. Copy what you need, then click the eject icon next to it in the sidebar (or drag the disc icon to the Trash).
3. From Terminal, hdiutil attach image.iso mounts it and hdiutil detach /Volumes/NAME ejects it.

Windows ISOs on a Mac: mounting a Windows ISO lets you browse its files, but you can't run the installer on macOS. Intel Macs can install Windows with Boot Camp Assistant (in Applications > Utilities), which asks for the ISO. Apple silicon Macs (M1 and later) don't support Boot Camp; there you run the Arm version of Windows 11 in a virtual machine app such as Parallels Desktop, VMware Fusion or UTM, which accept an ISO as the install disc.

If macOS says the image has no mountable file systems, the ISO is either incomplete (check it with the tool above for a size mismatch) or uses a filesystem macOS can't read. Extracting it with a tool such as The Unarchiver or Keka, or opening it inside a virtual machine, are the usual workarounds.

Open an ISO on Android or iPhone

Phones can't mount disc images, and you can't run a Windows or Linux installer on them, but you can still get at the files:

• Android: archive apps such as ZArchiver can open many ISO files and extract individual files from them. To write a Linux ISO to a USB stick connected by an OTG adapter, the open-source app EtchDroid does the same job as Etcher on a computer (it doesn't support official Windows ISOs from Microsoft).
• iPhone and iPad: the Files app can't open ISO images, and there's no way to use one on iOS. Move the file to a computer, or browse its contents in the tool at the top of this page, which also works in mobile Safari.

Create an ISO from a disc or folder

• Windows: there's no built-in "create ISO" option. The free ImgBurn has Create image file from disc (rip a CD/DVD to ISO) and Create image file from files/folders modes.
• Mac: in Terminal, hdiutil makehybrid -iso -joliet -o output.iso /path/to/folder builds an ISO that Windows can read. To image a physical disc, use Disk Utility's File > New Image > Image from the disc with the DVD/CD master format, then rename the resulting .cdr file to .iso.
• Linux: xorriso -as mkisofs -J -R -o output.iso folder/ (or the older genisoimage with the same options) creates an ISO with Joliet and Rock Ridge long filenames.

Copying a commercial DVD or Blu-ray that uses copy protection isn't covered here: in the US, circumventing that protection is generally prohibited under the DMCA, even for a personal backup.

Common ISO file problems and how to fix them

"This file isn't a valid disc image"

Check the Overview tab on this page's tool. If it can't find the "CD001" identifier at sector 16, the file either isn't actually an ISO 9660 image, or it's a different disc format (some older formats, and raw .bin/.cue images, don't use ISO 9660 directly).

"Couldn't Mount File" on Windows

Windows shows this message, or "The disc image file is corrupted", when File Explorer refuses to mount an image.

Work through these causes in order:

1. Incomplete download. Drop the ISO into the tool above; if it reports the file is smaller than the size its volume descriptor declares, re-download it (and compare the checksum if the source publishes one).
2. Sparse file flag. Some download tools and torrent clients save files as "sparse", which Windows won't mount. Open Command Prompt as administrator and run fsutil sparse setflag "C:\path\to\file.iso" 0, then try Mount again.
3. Blocked download. Right-click the ISO, choose Properties, and if there's an Unblock checkbox at the bottom of the General tab, tick it and click OK.
4. Unusual location. Copy the ISO to a folder on your internal drive (for example Downloads) rather than mounting it from a network share or a removable drive.
5. Not a standard ISO. If the tool above can't find a valid volume descriptor, the file may be a renamed BIN, IMG or DMG. Extract it with 7-Zip instead, or see the BIN guide.

ISO is too big to copy to a USB stick ("file is too large for the destination file system")

USB sticks formatted as FAT32 can't hold any single file over 4 GB, and many ISOs (Windows installers, DVD images) are larger. Either reformat the stick as exFAT or NTFS to store the ISO as a file, or — if you want to boot from it — write it with Rufus or Ventoy as described above, which deal with the limit for you.

Mounting fails or the drive appears empty

This page's tool will flag a size mismatch directly if the file is smaller than its own volume descriptor declares — a strong sign of an incomplete or corrupted download. Re-download the file and compare its size against the source.

Filenames look garbled or truncated

Base ISO 9660 (Level 1) limits filenames to 8.3-style uppercase names. If the source disc used Joliet or Rock Ridge extensions for longer names and your mounting tool doesn't support them, names can appear cut off. This page's tool reports whether Joliet is present so you know which case you're in.

Related file extensions

Technical references

The filesystem inside almost every ISO image is formally standardized, first by Ecma International and adopted equivalently by ISO.

• ECMA-119 — Volume and File Structure of CDROM for Information Interchange — the formal specification this page's tool implements: the Volume Descriptor Set, Primary Volume Descriptor field layout, and directory record structure.

Frequently asked questions