About this CRC32 calculator
CRC32 is a 32-bit cyclic redundancy check. It turns any data into a short number that changes if even one bit of the data changes, which is why ZIP and gzip files, PNG images, and Ethernet frames use it to catch accidental corruption. This calculator uses the standard IEEE 802.3 polynomial, the same variant as zlib and PHP’s crc32. It encodes your text in the character encoding you choose, shows the checksum as uppercase and lowercase hex, as a decimal number, and as 32 binary digits, and splits it into its four bytes so you can see each bit.
How to calculate a CRC32 checksum
- Enter your text. Type or paste text, or press an example to fill the box.
- Choose the encoding. Pick the Character encoding your data uses. UTF-8 is right for most text; the other encodings change the bytes and therefore the checksum.
- Press Calculate CRC32 checksum. The checksum appears in hex, decimal, and binary, with the four bytes shown bit by bit.
- Copy a value. Use the Copy button next to the format you need, or Copy hex at the top of the results.
Frequently asked questions
What is the CRC32 of 123456789?
It is CBF43926 in hex, 3421780262 in decimal. This string is the standard check value for CRC32, so if a tool gives something else, it uses a different polynomial or settings.
Why does the encoding change the checksum?
A checksum is computed on bytes, not characters. The word café is five bytes in UTF-8 but four in Latin-1, and UTF-16 stores every character in two bytes, so each encoding gives a different value.
What happens to characters ASCII or Latin-1 cannot hold?
They are written as a question mark before the checksum is calculated. ASCII holds code points up to 127 and Latin-1 up to 255, so use UTF-8 for emoji or other scripts.
Which UTF-16 and UTF-32 byte order is used?
Little-endian, with no byte order mark, which matches what most programming languages produce when they encode a string to UTF-16-LE or UTF-32-LE.
Can CRC32 be used for security?
No. CRC32 detects accidental errors, but it is easy to craft different data with the same value. Use SHA-256 or another cryptographic hash when you need to detect tampering.