TAR File Format (.tar)
A TAR file concatenates files, directories and 512-byte headers recording each item's owner, permissions and modification time into one stream, a format Unix introduced in 1979 for writing straight to magnetic tape with no compression involved.
TAR at a glance#
| Full name | Tape Archive |
|---|---|
| File extension | .tar |
| Category | Archives |
| First released | 1979 |
| MIME types | application/x-tar |
| Compression | Uncompressed |
| Specification | POSIX.1-2001 pax Interchange Format |
| FileFlip support | FileFlip reads and writes this format |
What a .tar file can hold#
These are the things a TAR file either supports or does not, and they are what decides whether a conversion keeps everything or quietly drops something.
| Embedded metadata | Yes |
|---|---|
| Streaming | Yes |
Strengths and limitations of TAR#
What TAR does well
- Preserves Unix ownership, permissions and symlinks exactly, which most non-Unix archive formats don't attempt
- Simple enough to stream: an archive can be built and read one entry at a time without seeking, which is what let it write straight to sequential tape drives
- Decades-old tarballs still extract cleanly with today's tar
Where TAR falls short
- No compression at all, so a tarball of ordinary files is roughly the same size as the files combined and always needs a separate compressor for that job
- Reading one file out of a tarball means scanning sequentially past everything before it, since there's no index like ZIP's central directory
- The original header format capped filenames at 100 characters and file size at 8 GB, fixed only by later GNU and pax extensions
Use TAR when file ownership, permissions and symlinks have to survive the trip, which matters for backups and Unix software distribution and doesn't matter for a folder of photos.
Convert an uncompressed TAR to a compressed variant like TGZ or TXZ when the archive is being stored or transferred and its size actually matters.
How to open a .tar file#
A .tar file opens in the programs below, grouped by the platform you are on. If you would rather not install anything, FileFlip converts TAR into a format your machine already opens, and it does it in the browser tab rather than on a server.
| Platform | Programs that open it |
|---|---|
| Windows | 7-Zip, WinRAR |
| macOS | Archive Utility, Terminal |
| Linux | Archive Manager (File Roller), tar (terminal) |
| Web | FileFlip |
TAR questions people ask#
Why does TAR need a compressor like gzip?
TAR only concatenates files and their metadata into one stream; it was designed in 1979 to write straight to magnetic tape and never included compression at all. That's why a tarball is normally paired with gzip, bzip2 or xz, producing .tar.gz, .tar.bz2 or .tar.xz.
Why is a TAR file about the same size as the files inside it?
A TAR archive stores file data unmodified, padded out to 512-byte blocks, so it only adds a small amount of header overhead per file rather than shrinking anything. Compressing it separately with gzip or xz is what actually reduces the size.
Can I extract one file from a large TAR archive?
Yes, tar can extract a single named file, but it reads sequentially through the archive until it reaches that entry, since TAR has no index like ZIP's central directory. On an uncompressed tarball this is fast; on a compressed .tar.gz it means decompressing everything up to that point too.
Does TAR preserve file permissions?
Yes, that's one of TAR's defining features: each entry's header records the owner, group, permission bits and modification time, which is why Unix backup tools and package formats still build on it. Most non-Unix archive formats, including the base 7z format, don't keep this information.
Converting TAR files#
Convert TAR to another format
Convert another format to TAR
Every conversion runs inside your browser. The file is read from your disk, the work happens on your own machine, and nothing is uploaded. How FileFlip works names the engine behind each family and how to verify that for yourself.