FormatDrop
Document Format

ISO

ISO 9660 / Optical Disc Image

An ISO file is a sector-by-sector copy of an optical disc — a complete image of a CD, DVD, or Blu-ray. The format uses the ISO 9660 file system (also called CDFS) defined in 1988. ISO files are how operating systems are distributed, software is archived, and disc content is preserved digitally.

What is ISO?

An ISO file consists of raw 2048-byte sectors that mirror the physical disc layout. The ISO 9660 file system specifies directory structures, file names, and metadata. Modern ISOs may include UDF (Universal Disk Format) for files larger than 4 GB or non-ASCII filenames. ISOs can be bootable (containing a boot sector for OS installation) or data-only.

ISO pros and cons

Advantages

  • Universal file system standard (ISO 9660)
  • Lossless preservation of disc content
  • Bootable ISOs install operating systems
  • Mountable on Windows 10+, macOS, and Linux without conversion
  • Compatible with every CD/DVD burning tool

Limitations

  • Limited to ISO 9660 or UDF — not modern file systems
  • Large file sizes (full disc image)
  • Cannot represent encrypted or copy-protected content perfectly
  • Bootable ISOs require specific structure (El Torito specification)

When should you convert ISO files?

Convert ISO to other formats only when needed: extract files with 7-Zip if you don't need disc structure; convert to DMG for macOS-specific use cases; create a USB-bootable image with Rufus or Etcher. For just reading files, mount the ISO directly — no conversion needed.

All FormatDrop conversions run entirely in your browser — no file upload, no server processing. Your files stay on your device.

ISO FAQ

How do I mount an ISO file on Windows?
Right-click the .iso file → Mount. Windows 10 and 11 mount ISO files as virtual drives natively. To unmount, right-click the virtual drive → Eject.
How do I extract files from an ISO without burning a disc?
Use 7-Zip (free, Windows): right-click the ISO → 7-Zip → Extract files. macOS: double-click to mount, then drag files out. Linux: `mount -o loop input.iso /mnt/iso` or `bsdtar -xvf input.iso`.
How do I burn an ISO to a USB drive?
Use Rufus (Windows), balenaEtcher (cross-platform), or `dd` (Linux/Mac): `dd if=input.iso of=/dev/sdX bs=4M status=progress`. The USB will become bootable if the ISO is a bootable installer.

More formats

HEICWebPAVIFEPUBWebMOpusMP3WAVM4AFLACAACMP4AVIMKVMOVJPGPNGGIFSVGTIFFICOBMPEPSARWOGGWMVPPTXPagesPDFDOCXRAWHEVCH.264AIFFM4VWMA3GPDNGRTFPSDOGVTSFLVAIXLSXCSVZIPAPNGMIDIJPEG XLMPG/MPEGVOBM2TSAC3ALACDTSJP2HEIFAPECBZ3G2SRTDOCPPTXLSODTODSM3URAR7ZM4BAMRTXTMOBITARGZJSONXMLYAMLKEYMTSCR2NEFMXFTGACAFASSVTTDSFRMF4VWVASFRMVBORFRW2EAC-3TTADMGXZDjVuFB2AUM4RAZW3MKAEXRVCFICSAAXPRCMP2SPXXSPFM3U8