Archive Converter

RAR was written by Eugene Roshal in the early 1990s and is still common on download sites, game mod pages and anywhere files are shared in split parts. It compresses well and has good recovery features, but it is a closed format: extraction code is freely available, while making RAR archives needs RARLAB's own software. That is why Windows, macOS and phones tend to treat RAR as an afterthought and why a RAR attachment often reaches someone who cannot open it.

Repacking it as ZIP fixes that in one step. ZIP is the one archive type with built-in support on Windows, macOS, Android and iPhone, so the receiver can double-click it. The files inside are not touched: documents, photos and programs are copied bit for bit from the old container to the new one. Only the compression method and the file list around them change.

The same applies to 7Z, TAR.GZ, TAR.BZ2 and TAR.XZ. They are all good formats, but each is at home in a smaller circle of tools. When a file has to work for someone whose setup you do not know, converting to ZIP is the safe default.

A conversion also works as a quick health check. If the source archive is damaged, for example because a download stopped early, the unpack step fails and tells you so, instead of a receiver finding out later that half the files are missing. Fixing that means downloading the original again; no converter can rebuild data that never arrived.

RAR is also on the target list for the cases where a site or a teammate asks for it explicitly, such as upload forms that only take RAR, or a workflow built around its recovery records. Choose Extract files (no archive) when you only want the loose files and no new container at all; for more control over folders, name encoding and nested archives, Unzip Online is the better fit. To bundle new files rather than repack an old archive, use the Zip Files tool.

A useful rule of thumb: pick the format your receiver already uses. Office colleagues and clients almost always mean ZIP. Developers and server administrators expect TAR.GZ or TAR.XZ, because Unix tools read them directly and keep paths and dates exactly. 7Z makes the most sense when you are both the sender and the receiver, for long-term storage or for moving a large folder of text-heavy files where every megabyte counts.

Disk images are a special case. An ISO follows the ECMA-119 layout used on CDs and DVDs, and a DMG is Apple's own disk image for Mac installers. Converting either one to ZIP makes its files readable on any system, while converting a folder of files to ISO gives you a disc image to mount in a virtual machine or burn to a blank disc.

Because the files are fully unpacked in the middle, the source password and the target password are independent. You can open a locked RAR and write an open ZIP, keep the same password on a new format, or add a password to an archive that never had one. The source password is used only to read the archive during this batch.

Compression level only affects the size of the result and the time it takes. Store writes the files without compressing them, which is fastest and makes sense for photos, music and video that will not get smaller anyway. Maximum searches harder for repeated data; it pays off on text, spreadsheets, logs and source code. Every level restores the original files exactly, so there is no quality trade-off to worry about.

Split RAR sets, named .part1.rar, .part2.rar and so on, work too, as long as every part is in the same batch. The tool reads them in order and writes one combined archive in the target format, which is often the simplest way to turn a multi-part download into a single ZIP.

Expect the size of the result to move a little in either direction. ZIP compresses each file on its own with the Deflate method, while 7Z and RAR can treat many similar files as one stream and find more repetition, so a 7Z of a folder of text files usually turns into a somewhat larger ZIP. Going the other way, a ZIP repacked as 7Z or TAR.XZ at Maximum often comes out smaller. Archives of photos, music or video barely change, because those files were compressed by their own formats long before they were archived.

Moving between Unix and Windows formats has one more detail. TAR records Unix permissions, owners and symbolic links, which tell a server which files may run and who owns them. ZIP keeps the files, folders and dates, but tools on Windows ignore most of that extra information. For anything that will be deployed to a Linux machine, keep a TAR-based format at the end of the chain.