Introduction
RAR is the archive format of WinRAR, created by Eugene Roshal in 1993. Its compression is proprietary: only WinRAR and RAR can create RAR archives, while the free UnRAR source code lets other programs extract them. It supports solid archives, archives split across several volumes, recovery records that can repair a damaged archive, and encryption.
There are two quite different formats with the same .rar extension. The
current one, RAR 5.0, came with WinRAR 5.0 in 2013. Archives made before that, and by
newer versions when asked for the old format, use the RAR 1.5 to 4.x layout. Both start
with the bytes Rar!, but their headers are built differently, so each has
its own page here.
Variations
| Format | Variation | About | Open |
|---|---|---|---|
.RAR | RAR 1.5 to 4.x archive (RAR4) | The older RAR format: blocks with a fixed 7-byte header and 16-bit CRC. | Open |
.RAR | RAR 5.0 archive (RAR5) | WinRAR’s current archive: CRC-32 block headers with variable-length numbers. | Open |
RAR 5.0 (RAR5)
The current format. Headers carry a CRC-32 and store sizes and types as variable-length numbers, so the format has no 4 GB limits. It adds AES-256 encryption, optional BLAKE2 file hashes, larger dictionaries and stronger recovery records.
The file starts with the 8-byte signature 52 61 72 21 1A 07 01 00
(Rar!, then 1A 07 01 00).
RAR 1.5 to 4.x (RAR4)
The older format, used from RAR 1.5 until WinRAR 5.0. Every block has a fixed 7-byte header with a 16-bit CRC, a one-byte type and 16-bit flags. Encrypted archives use AES-128.
The file starts with the 7-byte signature 52 61 72 21 1A 07 00
(Rar!, then 1A 07 00).
Links
Software
- WinRAR (Windows; RAR for macOS and Linux on the command line)
- 7-Zip, extract only (Windows)
- The Unarchiver, extract only (macOS)
- PeaZip, extract only (Windows, macOS, Linux)
- UnRAR, RARLAB’s free extractor and its source code
Reference
- RAR 5.0 archive format, RARLAB’s technical note