CRC32 Checksum

CRC32 calculator

This is a CRC32 calculator: it checksums bytes for accidental corruption, not for passwords. A CRC is an error-detecting checksum over bytes, not a password hash. This page computes the IEEE CRC-32 used by Ethernet, ZIP, PNG and gzip (polynomial 0x04C11DB7, reflected, init and xorout 0xFFFFFFFF). Identifiers such as CRC-32, CRC-32C, MPEG-2, BZIP2, JamCRC, IEEE, UTF-8, Hex, Base64, PNG and ZIP stay untranslated. Show Example hashes ASCII 123456789 to CBF43926 (the standard check value). CRC-32C of the same string is E3069283.

How to use

1. Paste text, hex, Base64 or 8-bit binary, or drop a file (max 10 MB). Auto convert is on.
2. Input Text uses Character Encoding (UTF-8 default, plus GBK, Big5, Shift_JIS, … the same list as Base64). Hex hashes the bytes you type, not the letters. Base64 and Binary decode to bytes first.
3. Algorithm: CRC-32 (IEEE), CRC-32C (Castagnoli / iSCSI), MPEG-2, BZIP2 or JamCRC (IEEE without the final XOR).
4. Output HEX / Hex / Decimal / Binary / Base64. Cards under the result always show all four. Verify compares an expected value such as CBF43926.
5. Chips: 123456789, JSON {"status":"ok","code":200} → 7CE63E7D, hex 010203040506 → 81F67724 (decimal 2180413220), and CRC-32C.

Input encodings

CRC32 hashes bytes. The same letters under GBK and UTF-8 give different sums. Hex 010203040506 is six bytes 01 02 03 04 05 06, not the ASCII of those digits. Binary input is groups of eight 0/1 bits. Files are hashed as raw bytes; typing in the box clears the file.

Variants (CRC-32 family)

All of these are 32-bit. CRC-32 (IEEE) is the default for ZIP/PNG/Ethernet. CRC-32C uses polynomial 0x1EDC6F41 (storage, SCTP, SSE4.2). MPEG-2 and BZIP2 use the IEEE polynomial but are not reflected; they differ in xorout. JamCRC is IEEE without xorout, so its hex is the bitwise NOT of IEEE for the same bytes (340BC6D9 vs CBF43926 for 123456789). Cards show Polynomial and Init for the selected variant.

What the output means

HEX is eight uppercase digits (32 bits). Decimal is the unsigned 32-bit integer. Binary is 32 bits in 8-bit groups. Base64 encodes the four big-endian bytes. CRC32 is not encryption and is not HMAC. Collisions are easy; use it for accidental corruption, not attackers.

Frequently asked questions

• Which polynomial? IEEE / ZIP / PNG is 0x04C11DB7 (reflected table 0xEDB88320). CRC-32C is 0x1EDC6F41.
• Same as the Hash tool? The Hash tool CRC32 option is IEEE only. This page adds CRC-32C, MPEG-2, BZIP2, JamCRC, Base64/binary input, file drop and verify.
• HMAC? CRC cannot be HMAC here. Open HMAC Generator.
• Does it upload? No. Computation stays in the browser.

Related tools

MD5/SHA: MD5 & SHA Hash. Keyed digest: HMAC Generator. Byte view: Hex Dump.