Convert TAR to IMG

A device or virtual machine may require a mountable raw disk image instead of the TAR archive supplied with software or firmware. The conversion must create a filesystem image and copy the archived files into it; changing the filename extension is not sufficient.

What the TAR format is

TAR is a sequential archive format that stores files and directories in one container; it does not define a filesystem, partition table, boot sector, or disk geometry. GNU tar, BSD tar, and Unix backup tools commonly create TAR files. Compression is separate and produces names such as .tar.gz, .tar.xz, and .tar.bz2. Source packages, Unix backups, firmware bundles, and software distributions are common uses.

What the IMG format is

IMG is a generic extension for an uncompressed raw disk image. Depending on the application, it can contain a floppy disk, an entire hard disk, a partition, removable-media filesystem, or another sector-addressable layout. Virtual machines, emulators, operating systems, and device-writing utilities can mount or write suitable IMG files directly.

An IMG file may contain only a filesystem or may also contain a partition table, boot sector, and bootloader. The receiving application determines the required filesystem, image size, partition layout, and boot structure. A CloneCD .img is an optical-disc image normally used with a matching .ccd file; it is not interchangeable with a generic FAT or ext4 filesystem image.

How to convert TAR to IMG on Linux

1. Inspect the archive and determine the required capacity. Allocate enough space for the extracted files, filesystem overhead, and future device requirements; use the exact capacity required by the target when it specifies one.
2. Create and mount a filesystem image, then extract the archive into the mounted filesystem. This example creates a 1 GiB FAT32 image:

tar -tf archive.tar
truncate -s 1G disk.img
mkfs.fat -F 32 disk.img
sudo mkdir -p /mnt/tar-img
sudo mount -o loop disk.img /mnt/tar-img
sudo tar -xf archive.tar -C /mnt/tar-img
sync
sudo umount /mnt/tar-img

GNU and BSD tar normally detect common compression formats, so the extraction command also works for many .tar.gz, .tar.xz, and .tar.bz2 files. Install dosfstools if mkfs.fat is unavailable. For a Unix-only target that requires ext4, replace the filesystem command with mkfs.ext4 -F disk.img; standard Windows installations do not natively read ext4.

truncate creates a sparse file whose logical size is 1 GiB. Use dd if=/dev/zero of=disk.img bs=1M count=1024 status=progress instead when the image must be fully allocated before writing it to media. This procedure creates a data image, not a bootable image.

How to convert TAR to IMG on Windows

Extract the TAR with 7-Zip. Create a new image with WinImage, choosing the required image type, filesystem, and capacity, then add the extracted files and save it with an .img extension. OSFMount and ImDisk can mount an existing image for inspection or copying, but they do not automatically convert a TAR archive into a correctly formatted image.

How to convert TAR to IMG on macOS

Extract the archive with tar -xf archive.tar or an archive utility. In Disk Utility → File → New Image → Blank Image, choose the required capacity and a compatible filesystem such as MS-DOS (FAT), mount the new image, copy the extracted files into it, and eject it. Disk Utility commonly saves a DMG container; use hdiutil convert with the raw read/write format, UDRW, when the receiving program specifically requires a raw IMG file, for example:

hdiutil convert source.dmg -format UDRW -o disk.img

Check the output filename because macOS utilities can append an extension. Verify the result with the target application before writing it to removable media.

Quality and compatibility limitations

This process preserves file contents, not the TAR container. FAT filesystems can discard Unix ownership, permissions, symbolic links, hard links, extended attributes, and sparse-file behavior. Use ext4 or another Unix filesystem when those attributes are required, and confirm that the receiving system supports it.

A normal TAR archive does not contain the source disk's partition table, boot sector, unused sectors, or bootloader. The resulting IMG is therefore not bootable unless you separately create the required partition layout and install or copy a compatible bootloader. If the TAR contains a complete .img file, extract that file instead of rebuilding it; renaming either the TAR or an extracted archive file does not perform a conversion.

Reputable online archive converters generally extract or repackage TAR files and do not reliably create an IMG with a selected filesystem, geometry, partition layout, boot configuration, and metadata policy. Use local tools for backups, firmware, credentials, or proprietary data. An online service is suitable only when it explicitly documents creation of the exact raw image type required and the files are safe to upload.