Convert ZIP to TAR Online (Compressed Container to Uncompressed Tape Archive)

What a ZIP File Actually Is Before Anything Gets Bundled Into TAR

A ZIP file is PKWARE's 1989 container format, still governed by the same public APPNOTE.TXT specification the company keeps updating. Every file inside gets compressed individually with DEFLATE by default, and every file's name, size, and exact byte location get recorded in a central directory stored at the very end of the archive. That trailing directory is why a program can open a 500-file ZIP and list its full contents almost instantly, without decompressing or even reading through the rest of the file — it only has to read the directory block at the end.

For archives holding more than 65,535 files, or containing any file larger than 4 GB, PKWARE's ZIP64 extension swaps the original 32-bit fields for 64-bit ones. This detail matters for a ZIP-to-TAR conversion specifically when the source archive is large: a TAR being built from the extracted contents inherits whatever files were in the ZIP64 archive, but TAR's own historical size limits (covered below) can then reintroduce similar constraints in the opposite direction.

TAR Has No Compression at All — It's Purely a File-Bundling Format

TAR, short for "tape archive," was originally built for writing files sequentially to magnetic tape drives, and its internal structure still reflects that: the format consists of a series of 512-byte blocks, where each file gets one header block describing its name, permissions, owner ID, group ID, size, and modification time, immediately followed by the file's raw data padded out to the next full 512-byte boundary. The archive ends with two consecutive all-zero blocks marking the end of the stream.

Critically, none of this involves compression in any form. A TAR file is exactly the combined size of everything it contains, plus a small amount of header overhead — converting a ZIP into TAR therefore, by itself, produces a larger file than the ZIP it came from, since DEFLATE's compression gets discarded entirely and nothing replaces it. This is also why the format has no equivalent to ZIP's central directory: reading a TAR means walking through the header blocks one at a time from the start, checking each file's declared size to know how many bytes to skip before reaching the next header, rather than jumping straight to a index of contents.

The original TAR header format also used fixed-width fields that topped out around 8 GB for a single file's size and had no separate provision for filenames longer than 100 characters. The POSIX "ustar" standard, published in 1988, extended these limits and formalized the header layout most modern tar implementations still use, and GNU tar adds its own further extensions on top for longer names and larger files. A ZIP-to-TAR conversion tool built on a current tar implementation handles all of this transparently, but it explains why extremely old tar readers occasionally choke on files a modern converter produces without issue.

What Repackaging a ZIP Into a Bare TAR Actually Trades Away

• Gain — real Unix permission bits, ownership, and symlinks: TAR's header stores the exact file mode, uid, and gid for every entry, while ZIP's handling of these Unix-specific attributes is inconsistent across tools.
• Gain — a format tools can write in a single, continuous pass: TAR was designed for streaming, so files can be appended to an outgoing tape or pipe one after another without needing to revisit an index.
• Lose — all compression: DEFLATE's space savings are simply gone; a bare TAR is uncompressed and typically bigger than the ZIP it was converted from.
• Lose — instant lookups of a single file: without a central directory, a program has to scan sequentially through headers to find a specific file rather than jumping straight to it.
• Lose — the near-universal double-click support ZIP gets on Windows: Windows Explorer has opened ZIP natively since Windows XP, but bare, uncompressed TAR needs a separate tool or the newer Windows 11 24H2 archive support to open by double-click.
• Gain — a format that fits naturally into Unix pipelines: because TAR has no built-in compression step, it composes cleanly with any external compressor piped in afterward, which is exactly how .tar.gz and .tar.bz2 get made.

Which Operating Systems Open a Bare TAR Without Installing Anything

macOS's built-in Archive Utility decompresses .tar files natively, alongside .zip, .gz, and .bz2, so a Mac user can double-click a plain TAR and have it expand without installing anything extra. Linux distributions ship the tar command as a core system utility, present by default on essentially every install, which is unsurprising given TAR's origins as a Unix tool.

Windows is the outlier here. Before the Windows 11 24H2 update, File Explorer had no built-in ability to open a .tar file at all, requiring 7-Zip or a similar third-party tool. The 24H2 update added native support for .tar alongside several other formats through the open-source libarchive library, but that native handling is limited to unencrypted archives — TAR itself has no native encryption feature to begin with, so this isn't a meaningful restriction for plain TAR specifically, though it does apply to the compressed TAR variants covered on other pages.

This asymmetry traces back to what each operating system's permission model actually needs. Linux and macOS rely on the owner, group, and permission-bit metadata that TAR's header format was built to store, so the tools that ship with those systems have every practical reason to support TAR out of the box. Windows historically didn't rely on that same Unix permission model day to day, so native TAR support wasn't a priority for File Explorer until Microsoft gave archive handling in general a broader overhaul in the 24H2 release.

The Actual Complaints Behind "My TAR File Is Bigger Than My ZIP"

A frequent point of confusion is a converted TAR file coming out noticeably larger than the source ZIP — this isn't a conversion error; it's the expected, documented result of TAR having no compression step of its own. Anyone converting a ZIP to TAR specifically to save space needs a compressed TAR variant like tar.gz or tar.bz2 instead, since bare TAR by design does the opposite of shrinking a file.

A separate, well-documented complaint on cross-platform file-transfer forums involves executable permission bits: files extracted from a ZIP archive on Windows and then re-zipped often lose their Unix "executable" flag, because ZIP's attribute handling for Unix permissions isn't consistently implemented across tools. Repackaging into TAR fixes this specific problem going forward, since TAR's header format includes the standard Unix file mode directly, but it can't restore a permission bit that a prior ZIP step already stripped — the fix has to happen by setting the correct permissions before the TAR is built, not after.

A third recurring issue involves very old tar implementations rejecting files with names longer than the original 100-character limit or sizes beyond the original fixed-width fields — both resolved by the POSIX ustar extensions and GNU tar's own extensions, which any current tar-based converter already applies automatically.

ZIP's Compressed Directory Against TAR's Bare Header Chain

Common Questions About Turning a ZIP Into a Plain TAR

Why is my TAR file bigger than the ZIP I converted it from?
Because TAR has no built-in compression at all. It's purely a bundling format, so a bare TAR is roughly the combined size of its contents plus small header overhead, while the ZIP it came from was compressed with DEFLATE.

Does converting to TAR fix permission problems from ZIP?
Going forward, yes — TAR's header format stores Unix file permissions and ownership directly. It can't restore a permission bit a prior ZIP step already stripped, only preserve permissions correctly from that point on.

Can I open a TAR file on Windows without installing anything?
Only on Windows 11 24H2 or later, which added native TAR extraction through libarchive. Earlier Windows versions need a separate tool such as 7-Zip.

If TAR doesn't compress, why does anyone use it?
Because it reliably preserves Unix metadata and bundles files into one stream that other tools, like gzip or bzip2, can then compress separately — that's exactly how .tar.gz and .tar.bz2 archives are built.

Is a bare, uncompressed TAR ever the right choice over ZIP?
Mainly when the priority is preserving exact Unix file permissions and ownership for later use on a Linux or macOS system, or when the files will be compressed separately in a following step, rather than when the priority is the smallest possible file size right away.