What is the ADF file format?
An .adf file is a raw binary image of a Commodore Amiga floppy disk, created by reading the disk track by track and writing every sector directly to a file without compression or modification. It captures the complete contents of the original floppy, including the AmigaDOS filesystem, boot code, and directory structure.
The standard double-density (DD) .adf image is always exactly 901,120 bytes - the product of 80 tracks × 2 sides × 11 sectors × 512 bytes per sector. High-density (HD) images, used with Amiga 4000 HD drives, are 1,802,240 bytes. Because the format is a literal dump with no wrapper, a file's size alone is the primary way to distinguish DD from HD images.
AmigaDOS disks write a bootblock into the first two sectors. The four-byte identifier at offset 0 reveals the filesystem variant: DOS\0 for Old File System (OFS) and DOS\1 for Fast File System (FFS). Game and utility disks often carried custom bootloaders that replaced the standard signature entirely.
In emulation, .adf files are mounted as virtual floppy drives by WinUAE, FS-UAE, and Amiberry. Linux users can mount them via fuseadf or extract files using unadf from ADFlib. For storage efficiency, many archives compress them as .ADZ files (gzip-wrapped ADF). More complex preservation formats - such as .IPF (SPS/CAPS Image File) - capture copy-protection timing data that raw ADF images cannot represent. Hard disk images for the same platform use the .HDF format.
Security & safety
RISK: MEDIUMAn Amiga ADF is passive disk data, but it is software someone else built: like any downloaded retro image it can carry the original disk's boot-block 'virus' (1980s/90s Amiga floppy viruses live in the bootblock), so run unknown ADFs in the emulator's sandbox, not on real hardware. Keep ROM/emulator use legal - Kickstart ROMs require a license (e.g. via Amiga Forever). Avoid generic 'ADF converter' sites that push PUP; use WinUAE/FS-UAE or ADFlib directly.
Format details
in a nutshell- Esri ARC/INFO Binary Grid / coverage - Legacy GIS raster/vector data stored as a folder of .adf files (w001001.adf, hdr.adf, prj.adf, etc.) opened in QGIS/ArcGIS/GDAL, not as a lone file.
- Amber Document Format - Niche application data format that also reuses the .adf extension.
Programs that open ADF files
Windows3 apps
WinUAE
Open-source The leading Windows Amiga emulator. Add the .adf to floppy drive DF0 in the Quickstart/Floppy settings and start the emulation. 
Amiga Forever (Cloanto)
Paid Commercial all-in-one Amiga emulation package with legal Kickstart ROMs; drag the .adf onto a configuration to run it. 
macOS1 app
Linux2 apps
FS-UAE / Amiberry
Open-source Mount the .adf as a floppy in the emulator (Amiberry is ideal on Raspberry Pi).
fuseadf / ADFlib (unadf)
Open-source Extract files without an emulator: 'unadf disk.adf' lists/extracts the AmigaDOS OFS/FFS contents, or mount read-only with 'fuseadf disk.adf /mnt'. Technical details
deep spec| Format type | Raw sector-by-sector floppy disk image; no compression or wrapper |
| DD image size | 901,120 bytes (880 KB) - 80 tracks × 2 sides × 11 sectors × 512 bytes/sector |
| HD image size | 1,802,240 bytes (1.76 MB) - 80 tracks × 2 sides × 22 sectors × 512 bytes/sector |
| Bootblock signature | "DOS\0" = OFS, "DOS\1" = FFS at byte offset 0; custom disks may have non-standard signatures |
| AmigaDOS filesystems | OFS (Old File System) and FFS (Fast File System) |
| Sector size | 512 bytes |
| Bootblock size | First 1,024 bytes (2 sectors); contains boot code executed on Amiga startup |
| MIME type | application/octet-stream |
| Compression | None - raw binary; compressed variant is .adz (gzip wrapper around ADF) |
| Emulator mount support | Directly mountable as virtual floppy in WinUAE, FS-UAE, and Amiberry |
| Linux tooling | fuseadf (FUSE mount) and unadf (file extraction) via the ADFlib library |
| Platform of origin | Commodore Amiga (A500, A600, A1200, A2000, A4000 series) |
| Byte order | Big-endian (Motorola 68000 architecture) |
| Copy-protection limitation | Cannot reproduce non-standard track timing or weak sectors; IPF and ADF+ formats address this |
| Released | Late 1980s (Amiga era) |
| Open standard | Yes · royalty-free |
| Specification | en.wikipedia.org |
ADF conversions
Community Q&A
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