CRC Calculator - CRC-32 / CRC-16 / CRC-8 Checksums (Free)

Built-in check ("123456789")

Each algorithm is verified against its published check value for the input string 123456789. This runs in your browser every time the page loads.

Algorithm	Computed	Published check value	Result

Frequently asked questions (FAQ)

What is the difference between CRC-32 and CRC-32C?

The generator polynomial. CRC-32/ISO-HDLC uses 0x04C11DB7 and CRC-32C/ISCSI (Castagnoli) uses 0x1EDC6F41. zip and PNG use the former; iSCSI and some file systems use the latter. The same data gives different values.

My CRC-16 does not match another tool. Why?

CRC-16 has several variants. The polynomial, init value, input and output bit reflection and final XOR all change the result. This tool shows ARC, IBM-3740 (CCITT-FALSE), MODBUS and XMODEM side by side, with their parameters, so you can find the one the other side uses.

How do I know the results are correct?

See the built-in check at the bottom of the page. Every CRC variant has a published check value for the input string 123456789. This tool recomputes all nine on every page load and shows whether they match the published values.

Can CRC replace a cryptographic hash?

No. CRC is an error-detecting code for accidental bit errors in transmission or storage. It is not designed to detect deliberate tampering. Use SHA-256 or similar when tamper detection is the goal.

Is my data or file uploaded to a server?

No. Both the calculation and the file reading happen entirely in your browser. Nothing is sent to or stored on a server.