CRC-32 Checksum Calculator
Calculate CRC-32 checksums: zip/PNG CRC-32, CRC-32C (Castagnoli), BZIP2, MPEG-2, POSIX cksum, JAMCRC or custom parameters, from text, hex or Base64 input.
Same value as zlib.crc32 in Python, crc32() and hash("crc32b") in PHP, and the CRC field in zip, gzip and PNG files.
| Variant | Hex | Decimal |
|---|---|---|
| CRC-32 (ISO-HDLC) | CBF43926 | 3,421,780,262 |
| CRC-32C (iSCSI) | E3069283 | 3,808,858,755 |
| CRC-32/BZIP2 | FC891918 | 4,236,843,288 |
| CRC-32/MPEG-2 | 0376E6E7 | 58,124,007 |
| CRC-32/CKSUM | 765E7680 | 1,985,902,208 |
| CRC-32/JAMCRC | 340BC6D9 | 873,187,033 |
| CRC-32/AUTOSAR | 1697D06A | 379,048,042 |
| CRC-32D (BASE91-D) | 87315576 | 2,268,157,302 |
| CRC-32Q (AIXM) | 3010BF7F | 806,403,967 |
| CRC-32/CD-ROM-EDC | 6EC2EDC4 | 1,858,268,612 |
| CRC-32/XFER | BD0BE338 | 3,171,672,888 |
A CRC-32 is a 32-bit checksum that detects accidental changes to data: zip, gzip and PNG files store one for every entry, and storage systems use CRC-32C to spot corrupted blocks. "CRC-32" is really a family, though — the polynomial, starting value, bit order and final XOR differ between variants, which is why two tools can disagree. This calculator covers the common presets from the CRC catalogue and lets you enter custom parameters, for text, hex or Base64 input.
How to use this tool
- Paste the text, or hex or Base64 bytes, and say which it is.
- Pick the CRC variant your system uses (CRC-32 for zip/PNG/PHP crc32, CRC-32C for iSCSI and cloud storage).
- Read the checksum in hex, decimal or Base64; the table shows every preset at once.
- Tick per-line mode to checksum each line separately.
Formula
CRC = reflect?(remainder of (input · x³²) ÷ P(x) over GF(2), starting from the initial register) XOR xorout
P(x) is the generator polynomial (0x04C11DB7 for CRC-32, 0x1EDC6F41 for CRC-32C). "Reflect input" processes each byte least-significant bit first; "reflect output" mirrors the 32-bit result. The check value — the CRC of the ASCII text 123456789 — identifies a variant unambiguously.
Example
The ASCII text 123456789 gives CBF43926 with standard CRC-32, E3069283 with CRC-32C, FC891918 with BZIP2 and 0376E6E7 with MPEG-2 — the check values listed in the CRC catalogue. PHP’s crc32("The quick brown fox jumped over the lazy dog.") is 2191738434, and the tool gives the same.
Frequently asked questions
Is CRC-32 a secure hash?
No. A CRC detects accidental errors, but anyone can change data and fix up the CRC. Use SHA-256 to check that a download has not been tampered with.
Why does my result differ from another tool?
It is probably another variant, or the input bytes differ (text encoding, a trailing newline, hex versus text). Compare the check value of "123456789" to identify the variant.
Why does POSIX cksum print a different number?
cksum uses the CRC-32/CKSUM parameters but also processes the length of the input after the data, so its output differs from the bare algorithm.
Sources
Last updated:
Page address with these inputs: https://kakao.mobile/tools/crc32-checksum-tool/
Cite or embed this tool
kakaoCalc. (2026, November 8). CRC-32 Checksum Calculator. https://kakao.mobile/tools/crc32-checksum-tool/
“CRC-32 Checksum Calculator.” kakaoCalc, 8 Nov. 2026, kakao.mobile/tools/crc32-checksum-tool/.
Paste this code into your page. The widget runs in your visitors' browsers, shows no ads and keeps a link back to this page. Embedding terms