Convert Any File to TAR Online (Bundling Without Compressing)

What Happens to a File the Moment It Enters a TAR Archive

Whether the source is a single document, a photo, a folder of source code, or an entire directory pulled from a server, tar treats it exactly the same way: it writes a 512-byte header recording that item's filename, size, Unix permission bits, numeric owner and group IDs, and modification timestamp, immediately followed by the file's raw, unmodified bytes padded out to the next 512-byte boundary. Tar dates back to Seventh Edition Unix in 1979, built specifically to write files sequentially to magnetic tape drives, and its header-then-data structure hasn't fundamentally changed since being standardized as USTAR under POSIX.1-1988.

Critically, none of that involves compression. The file's actual content passes through completely untouched — tar's only job is bundling and recording metadata, not shrinking anything. A single 10 MB file wrapped in a .tar comes out around 10 MB plus roughly 1 KB of header and padding overhead, regardless of whether that file was a text document, a photo, or already-compressed video.

Why the Source File Type Almost Never Matters to Tar Itself

Because tar performs no compression and no content analysis, the actual nature of the source file — whether it's plain text, a spreadsheet, a JPEG photo, or a compiled executable — has essentially no effect on how tar processes it. The only things that genuinely matter to tar are structural: the file's name (and whether it exceeds the classic 100-character USTAR limit, which forces either a 155-byte prefix field or a GNU-specific long-name extension), whether it's a regular file, directory, or symbolic link, and how large it is relative to the 512-byte block size tar always rounds up to.

This is a real point of difference from formats like ZIP or 7z, where the type of content genuinely changes how much a converter has to think about — those formats' compression stage behaves very differently on text versus already-compressed media. Tar has no such stage to worry about, which is exactly why bundling a folder of completely mixed file types into a single .tar is a structurally simple, predictable operation regardless of what's actually inside.

One structural detail does depend on the relationship between source files rather than their type: when several files being bundled are actually hard links to the same underlying data on disk, tar stores the file's contents only once, writing every additional hard-linked name as a special link-type header entry that points back to the first occurrence rather than duplicating the data. This means bundling a directory full of hard-linked files into a .tar can produce a noticeably smaller archive than the sum of each file's reported size would suggest — a genuine space saving that has nothing to do with compression and everything to do with tar recognizing the files share the same inode.

Plain Unix permission bits and ownership are only part of what a source file can carry, though. POSIX Access Control Lists and SELinux security contexts are separate, more granular attributes that a strict USTAR header has no field for at all — GNU tar added dedicated --acls, --selinux, and --xattrs options to capture them anyway, storing that extra data as extended PAX-style header records rather than in the original fixed 512-byte USTAR fields. Bundling a file that carries an ACL or SELinux label without one of those flags set means that specific extra metadata simply isn't recorded, even though the file's basic permission bits still are.

What Bundling Any File Into TAR Gains and What It Costs

• Gain — full Unix metadata capture, regardless of source type: permissions, ownership, and modification time get recorded in the header the same way whether the source is a document, an image, or a binary.
• Gain — a single file out of many, useful for transfer or storage organization: bundling scattered files into one .tar makes moving or archiving them as a set simpler, independent of what those files actually are.
• Gain — near-universal openability afterward: GNU tar, BSD tar, and Windows' own tar.exe all read plain TAR archives without extra installation on any of the three major desktop operating systems.
• Lose — no size reduction at all: unlike converting to a compressed format, wrapping any file in tar leaves its size essentially unchanged, aside from small header overhead.
• Lose — no encryption: the format has no built-in password-protection mechanism for any kind of source content.
• Lose — no fast content listing: there's no central directory, so checking what's inside a large .tar built from many files means reading through the entire archive sequentially.
• Gain — automatic hard-link deduplication: when source files being bundled are hard links to the same data, tar stores that data once and records the rest as link entries, which can shrink the archive below the combined reported size of the originals.

Which Tools Build a TAR Archive From Arbitrary Source Files

GNU tar, the default on virtually every Linux distribution, bundles any file or directory with a single command: tar -cf output.tar source-files, with no compression flag needed since plain tar creation never involves one. BSD tar, based on the libarchive project and the default on macOS, uses equivalent syntax and produces USTAR-compatible output that GNU tar reads correctly in return.

Windows has shipped its own native tar.exe since Windows 10 Insider Build 17063 in 2018, also built on libarchive, meaning a Windows command prompt can bundle arbitrary files into a .tar with no separate software installation. 7-Zip and PeaZip additionally offer graphical, point-and-click routes to the same result on Windows and Linux, letting a user select any mix of files or folders and choose tar as the output container directly from the archive-creation dialog.

Windows 11's 24H2 update extended this further by adding native File Explorer support for tar archives, built on the same libarchive foundation, so recognizing and opening a .tar file built from any kind of source content no longer needs a separate application installed on a current Windows system.

Real Complaints About Bundling Mixed Source Files Into TAR

A frequent point of confusion involves someone bundling files into a .tar expecting some amount of size reduction, since almost every other "compress this" workflow they've used actually shrinks things — tar's complete lack of compression catches people off guard specifically because so many other formats bundle compression and archiving together by default, while tar deliberately keeps them separate.

A second documented issue involves filenames longer than the classic 100-character USTAR limit getting mishandled when the archive is later opened with an older or stricter tar implementation that doesn't fully support GNU tar's long-name extension or USTAR's 155-byte prefix field — a real compatibility gap tied to which specific tool wrote versus which tool later reads the archive.

A third reported pattern involves numeric UID and GID values recorded in the tar header not matching any real account on a different machine later extracting the archive, since ownership in tar is stored as plain numbers tied to whatever system originally created it — files can come out owned by unfamiliar or nonexistent users regardless of what type of content those files actually were.

How Different Source Types Fare Once Bundled Into TAR

Common Questions About Converting Files Into a TAR Archive

Will bundling my files into a TAR make them smaller?
No. Tar applies zero compression regardless of what kind of files are inside — the result is close to the same total size as the originals, plus a small amount of header overhead per file.

Does the type of file affect how tar processes it?
Barely. Tar doesn't analyze or compress content, so a text file, a photo, and a binary executable all get the same treatment: a 512-byte header followed by the file's unmodified bytes.

Can I bundle files into a TAR on Windows without installing anything?
Yes, since Windows 10 Insider Build 17063 in 2018, which added a native tar.exe built on the libarchive project. Windows 11's 24H2 update also added direct File Explorer support for tar archives.

What happens to files with names longer than 100 characters?
GNU tar handles them using its own long-filename extension; the older USTAR standard instead uses a 155-byte prefix field that not every tool fully implements — long names can occasionally get mishandled depending on which specific tool later reads the archive.

Are Unix permissions preserved no matter what kind of file I bundle?
Yes. Tar's header stores permission bits, ownership, and modification time directly for every entry, regardless of whether the underlying content is a document, an image, or a compiled program.

Does bundling hard-linked files into a TAR store duplicate copies?
No. Tar recognizes when several files being archived are hard links to the same underlying data and stores that data only once, writing every additional linked name as a special link entry that points back to the first occurrence — the resulting archive can end up smaller than the combined reported size of the source files.