CRC32 Checksum Calculator
Calculate CRC-32 for UTF-8 text or a local file and compare an eight-digit checksum. Includes the 123456789 test vector and explains CRC32 versus CRC32C.
Your result will appear here.
How to calculate and compare CRC32
- Enter text or choose a local file; a selected file replaces the text as the source.
- To compare, paste just the expected eight hexadecimal digits.
- Calculate and check the comparison, then copy or download the checksum.
Working with CRC32 Checksum Calculator
This tool uses CRC-32/ISO-HDLC, the common ZIP and Ethernet variant. CRC32 detects accidental corruption; it does not protect against deliberate tampering. CRC32C is a different algorithm and produces different results.
CRC32 example: the standard 123456789 test vector
- Input
123456789- Result
cbf43926
Questions about CRC32 Checksum Calculator
Which CRC32 variant does this calculator use?
It uses CRC-32/ISO-HDLC, also commonly called IEEE CRC-32, with polynomial 0x04C11DB7. The text 123456789 gives cbf43926. CRC32C uses a different polynomial and gives a different result. Output is eight lowercase hexadecimal digits with leading zeros; empty input gives 00000000.
Why is the CRC32 of my ZIP different from a value inside it?
Selecting a ZIP calculates the checksum of the entire archive file. A CRC stored for an entry inside the ZIP describes that entry's uncompressed bytes, not the whole ZIP. Extract the entry and select that file to compare its CRC. Filenames and paths are not included in the calculation.
How do I compare a CRC32, and why might it differ?
Paste only the expected eight-digit hexadecimal value, without 0x or a filename. Comparison ignores case and whitespace at the ends. Text uses UTF-8 without trimming or normalization, so spaces, CRLF versus LF, a final newline and UTF-8 BOM can change the result. Files use exact bytes. Limits are 8 MiB of text and 32 MiB per file.
Can CRC32 verify security or encrypt data?
CRC32 detects accidental corruption; it is neither encryption nor a cryptographic hash. Different data can share the same CRC, and it does not prevent intentional tampering. Use SHA-256 for stronger file integrity checks with a trusted checksum, or the HMAC tool for message authentication with a secret key.
Are my files, tokens or text uploaded?
No. These tools process your input in your browser. The website serves the page and its code, but your input is not sent to a conversion server or saved in an account.
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Your input and files are processed on your device. Keep sensitive results out of shared clipboards and use a trusted device for private keys and tokens.