CRC Calculator
Compute CRC checksums for 7 common polynomials simultaneously.
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💡 Usage & Formula
CRC (Cyclic Redundancy Check) is an error-detecting code based on binary polynomial division, widely used in storage devices and networks.
Common Polynomials:
- CRC-8 (SMBus):
x^8 + x^2 + x + 1 (0x07) - CRC-16 (Modbus):
x^16 + x^15 + x^2 + 1 (0x8005) - CRC-32 (Ethernet):
0x04C11DB7
Usage: Select either ASCII text or Hexadecimal bytes input, choose your target polynomial, and view the calculated CRC checksum instantly.
When you need it: Computing a CRC over a byte string to compare against the value a device or protocol reports, while bringing up a link or chasing an intermittent corruption bug.
Worked example: The CRC-32 of the ASCII string "123456789" is 0xCBF43926, and CRC-16/Modbus of the same string is 0x4B37 — the standard check values every implementation should reproduce.
Tips & gotchas:
- Two CRCs of the "same" width can still differ — the polynomial, init value, and bit-reflection must all match.
- Hex input must be whole bytes; a stray nibble shifts every subsequent byte and changes the result.
- Modbus RTU sends its CRC-16 low byte first (little-endian on the wire); check byte order before comparing.
- A matching CRC means "very probably intact", not "authentic" — it is not a signature.