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ISO vs IMG

A side-by-side feature comparison.

Summary

ISO and IMG are both raw disc images, but ISO follows the ISO 9660 / UDF filesystem standards while IMG is a generic sector dump. ISO files mount on every operating system; IMG sometimes needs the right tool to interpret its filesystem.

Bottom line: ISO for distributing optical media. IMG for raw disk dumps and floppy images.

Feature comparison

Feature ISO (ISO 9660 image) IMG (Raw disk image)
Filesystem ISO 9660 / UDF / Joliet Anything (FAT, NTFS, raw)
Size Optical media (~9 GB) Unlimited
Native mount on Windows Yes (since Win 8) Often via Disk Management
Native mount on macOS Yes Sometimes
Native mount on Linux Yes Yes via loop device
Common use OS install media Disk and floppy backups

About ISO (ISO 9660 image)

An ISO file is a sector-by-sector image of an ISO 9660 (or UDF) optical disc. ISOs are the standard way to distribute Linux installers, bootable rescue media, and game discs. Modern Windows can mount an ISO with a double-click and write it to USB with built-in tools.

Read the full ISO (ISO 9660 image) guide →

About IMG (Raw disk image)

.img is a generic name for a raw, byte-for-byte disk image. Unlike ISO it can contain any filesystem (FAT, ext4, APFS, NTFS) and even partition tables. Raspberry Pi OS, Linux distros, and embedded firmware are commonly distributed as .img.gz files for direct flashing to SD cards or USB sticks.

Read the full IMG (Raw disk image) guide →

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