How to calculate a CRC32 checksum
- Type or paste text, or switch to File and drop a file.
- The 8-character CRC32 value is shown first, in hexadecimal. Tick Uppercase if your tool prints it that way.
- Paste a known value into Compare to check whether they match.
What CRC32 is for
A cyclic redundancy check is a fast error-detecting code. CRC-32 (the IEEE 802.3 polynomial 0xEDB88320, reflected) is the variant used in ZIP and gzip archives, PNG image chunks, Ethernet frames, SATA, and many file formats and network protocols. It reliably detects accidental changes such as flipped bits or truncated transfers, and is extremely cheap to compute.
CRC32 is not a cryptographic hash. It is easy to create a different file with the same CRC on purpose, so never use it to detect tampering or as a security check; use SHA-256 for that. It is also only 32 bits, so with millions of files, accidental collisions become likely.
Typical uses are checking an archive entry's stored CRC, matching checksums in emulator ROM sets, debugging binary protocols, and quick deduplication in small collections. Everything is calculated in your browser.
FAQ
What is the CRC32 of "The quick brown fox jumps over the lazy dog"?
414fa339, the standard test value for CRC-32/ISO-HDLC.
Is CRC32 the same as CRC32C?
No. CRC32C (Castagnoli) uses a different polynomial and is used by iSCSI, ext4 and Google Cloud Storage. This tool calculates the common IEEE CRC-32.
Why do some tools show a different value?
They may use another CRC variant, show the value byte-reversed, or include a trailing newline in the input.