CRC-32 Hash Generator

Calculate CRC-32 and CRC-32C checksums of text or files.

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CRC-32 (ISO-HDLC, zip, PNG)
CRC-32C (Castagnoli, iSCSI)
CRC-32/BZIP2
CRC-32/MPEG-2
CRC-32/POSIX (cksum)
CRC-32/JAMCRC
CRC-32 (ISO-HDLC, zip, PNG) · 32 bits

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CRC-32C (Castagnoli, iSCSI) · 32 bits

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CRC-32/BZIP2 · 32 bits

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CRC-32/MPEG-2 · 32 bits

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CRC-32/POSIX (cksum) · 32 bits

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CRC-32/JAMCRC · 32 bits

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CRC-32 Hash Generator

Calculate CRC-32 checksums of text, hex bytes, or a file in the most common variants at once: the standard CRC-32 (ZIP, PNG, Ethernet), CRC-32C (Castagnoli), BZIP2, MPEG-2, POSIX cksum, and JAMCRC. Everything runs in your browser.

What is CRC-32?

A 32-bit Cyclic Redundancy Check divides the data, viewed as a polynomial, by a fixed generator and keeps the 32-bit remainder. It is the workhorse error-detection code of computing: ZIP and gzip archives, PNG chunks, Ethernet frames, and countless file formats store a CRC-32 to catch corruption. For the standard test string 123456789, CRC-32 gives 0xCBF43926.

Variants included

  • CRC-32 (ISO-HDLC) – ZIP, gzip, PNG, Ethernet
  • CRC-32C (Castagnoli) – iSCSI, SCTP, ext4, hardware-accelerated
  • CRC-32/BZIP2 and CRC-32/MPEG-2 – non-reflected variants
  • CRC-32/POSIX – the Unix cksum command
  • CRC-32/JAMCRC

Features

  • All variants at once, with chips to show or hide each
  • Text, hex, Base64, or file input, up to 200 MB
  • Hex or decimal output
  • Compare with a known value

For 16-bit protocol checks see the CRC-16 Hash Generator; for Adler-32, Fletcher, and sum checksums see the Checksum Calculator. For secure hashing use the SHA256 Hash Generator.

Frequently Asked Questions

Both use the standard CRC-32 (ISO-HDLC): polynomial 0x04C11DB7, initial and final value 0xFFFFFFFF, with reflected input and output. Its check value for \"123456789\" is 0xCBF43926. That is the CRC-32 row here.

CRC-32C uses the Castagnoli polynomial (0x1EDC6F41) and has better error-detection properties. It is used by iSCSI, SCTP, ext4 metadata, and is accelerated by a dedicated CPU instruction (SSE4.2 crc32).

It is fast but only 32 bits, so accidental collisions are possible across large collections, and it offers no protection against deliberate tampering. For de-duplication or integrity against attackers, use SHA-256 instead.

Either the variant differs (BZIP2, MPEG-2, and POSIX cksum all differ from the standard CRC-32) or the input bytes differ, often due to a trailing newline or text encoding. Compare against the documented check values shown for each variant.