A free archive converter for ZIP, RAR, 7Z, TAR, ISO, CAB, DEB, RPM and any of 15+ archive types: see every file and any risky paths inside, then repack it as one of 15 formats. Everything runs in this tab, and the new archive is read back and compared byte for byte before you download it.
We packed the same two folders into every format and measured the results: 2.3 MB of source code, logs and CSV data, and 3.9 MB of photographs and audio. Packed with 7-Zip 26.02. What you archive matters far more than which format you choose.
Measured on two representative folders with 7-Zip at maximum settings. Your own results depend heavily on what is inside the archive.
Archivers bundle many files into one; compressors shrink a single stream. Tarballs like TGZ and TXZ are one of each.
Every archive and compression format starts with a signature at a fixed position. Most sit at byte 0, but tar puts “ustar” at byte 257 and an ISO disc image puts “CD001” at byte 32,769. Pick an example, or choose a file from your computer. Only its first 33 KB are read, in your browser, and it all stays on your device.
tar was designed for magnetic tape in 1979 and never compresses anything. Each file gets a 512-byte header, numbers written as octal ASCII digits, then its contents padded to the next 512 bytes. Two empty blocks mark the end. Compression is a separate step: a .tar.gz is this whole stream run through gzip. The archive below is built live, checksum included, and downloads as a real .tar.
One click packs the archive open above (or the sample) into every format this page writes, opens each result again and compares every file byte for byte. Next to the measurements: what each format is able to store besides the bytes.