How to Open ISO Files: Mount, Extract or Write Them to USB
An ISO file is a complete copy of a CD, DVD or Blu-ray disc in a single file. You rarely need special software to read one: Windows, macOS and Linux can all "mount" an ISO as if a disc were inserted. This guide explains when to mount, when to extract, and when you need to write the image to a USB stick instead.
Updated 2026-10-13 · Written and tested by the UnpackNest editorial team (TECCONET)
First, an honest note: UnpackNest does not open ISO files
UnpackNest's browser tools open RAR, ZIP, 7z, TAR and GZ archives. We have not built or tested an ISO reader, so we do not offer one. ISO images are also often several gigabytes, which is more than a browser tab can comfortably hold in memory. Your operating system already has a better tool for the job, and the steps below use it. Nothing in this guide requires uploading the image anywhere.
What is inside an ISO
An ISO image stores a disc's file system, usually ISO 9660 and often UDF as well, plus, for bootable discs, a small boot record. That is why an ISO is not quite the same as a ZIP: it is not just a list of compressed files, it is a byte-for-byte picture of a disc. Most ISOs are not compressed at all. Common sources are operating system installers (Windows, Linux distributions), old software discs and backups of your own CDs or DVDs.
Three things you might want to do
| Goal | Best method | Why |
|---|---|---|
| Look at or copy a few files | Mount the ISO | Instant, nothing is copied until you choose |
| Get all files into a normal folder | Extract with 7-Zip or copy from the mounted drive | Gives you editable files |
| Install an operating system on a PC | Write the ISO to a USB stick with a dedicated tool | Copying files is not enough to make a USB bootable |
Windows 10 and 11: mount
- Find the .iso in File Explorer.
- Double-click it, or right-click and choose Mount.
- A new "DVD drive" appears under This PC with its own letter, for example E:.
- Open it and copy the files you need to a normal folder.
- When you are finished, right-click the drive and choose Eject.
If double-clicking opens another program (an old burning tool may have taken over .iso files), right-click and choose Open with > Windows Explorer.
macOS: mount
- Double-click the .iso in Finder. macOS mounts it and shows it on the desktop and in the Finder sidebar.
- Copy what you need.
- Eject it with the eject button in the sidebar.
Some Windows-only images use only UDF features that macOS cannot read and show an error; in that case, use 7-Zip on another machine, or Keka or The Unarchiver, which can extract many ISOs.
Linux: mount
On most desktops, right-click the ISO and choose Open With Disk Image Mounter. In a terminal:
mkdir ~/isosudo mount -o loop,ro image.iso ~/iso- Copy files from
~/iso, thensudo umount ~/iso.
Extract all files with 7-Zip
7-Zip reads ISO 9660 and UDF images and can extract them like any archive. That is handy on a computer where you cannot mount images, or when you want a permanent folder copy.
- Install 7-Zip from 7-zip.org (Windows) or the
7zippackage (Linux). - Right-click the ISO, choose 7-Zip > Extract to "name\".
- On Linux:
7zz x image.iso -oimage.
Extracting a Windows installer ISO to a folder and running setup.exe from it works for upgrades. It does not create bootable media.
Make a bootable USB stick
To install Windows or Linux on a computer, the ISO's contents and its boot record must be written to a USB stick in the right way. Copying files with File Explorer does not do that.
- Windows installer: Microsoft's Media Creation Tool downloads and writes the image for you.
- Any ISO on Windows: Rufus (rufus.ie) is a small, well-known open-source tool.
- Windows, macOS or Linux: balenaEtcher writes images with a simple three-step interface.
- Linux terminal:
ddworks, but a wrong device name erases the wrong disk. Prefer a graphical tool unless you are sure.
Writing an image erases everything on the USB stick. Copy anything you need from it first.
Check the image before you trust it
ISO files are a popular way to distribute operating systems, so they are also used to distribute fake ones. Before you install from an image:
- Download only from the publisher's own site.
- Compare the published SHA-256 checksum. Windows:
certutil -hashfile image.iso SHA256. macOS or Linux:shasum -a 256 image.iso. - If the publisher also offers a signature (many Linux distributions do), verify it.
A matching checksum proves you have the same file the publisher listed. It does not prove the publisher is trustworthy, which is why the source matters.
ISO files in email and chat
Criminals have mailed ISO and IMG files because, for a while, files inside a mounted image did not inherit Windows's "downloaded from the internet" warning. Microsoft closed that gap in late 2022, but an unexpected ISO in an email is still a red flag. A real business rarely sends documents as a disc image. Do not open programs or shortcuts (.lnk) from such an image.
Other disc image formats
- .img: often the same as an ISO, or a raw disk image. Windows can mount many .img files the same way.
- .dmg: Apple disk image; opens natively on macOS. 7-Zip can read many of them on Windows.
- .bin/.cue, .nrg, .mdf: older burning formats; specialised tools or conversion to ISO may be needed.
Frequently asked questions
Can I open an ISO on my phone?
Not usefully. Phones cannot mount ISO images, and most ISOs are installers for computers. Copy the image to a computer instead.
Will UnpackNest add ISO support?
Not in the current version. If it is added later, this guide will say so and link to the tool. Until then, your system's mount feature is the right tool.
Is mounting an ISO safe?
Mounting only shows the files. The risk comes from running programs inside it, so the same caution applies as for any download.
Why is the ISO larger than the files inside?
ISOs are rarely compressed and include file system structures and padding. Compressing an ISO with 7z or ZIP often makes it smaller.