LRC (Longitudinal Redundancy Check) is a simple checksum computed by XORing all bytes, then taking the two's complement. It's used in magnetic stripe cards, Modbus ASCII, and various serial protocols.

LRC is used in ISO 7811 magnetic stripe cards (credit cards), Modbus ASCII protocol, some barcode systems, and legacy serial communication protocols.

LRC adds a two's complement step after XORing all bytes: LRC = (~XOR + 1) & 0xFF. This means XOR + LRC = 0x00, making verification simple.

LRC = Two's complement of (sum of all bytes XORed together). In code: lrc = ((~xor) + 1) & 0xFF, or equivalently: lrc = (256 - xor) & 0xFF.

XOR all data bytes including the LRC byte. The result should be 0x00 if the data is valid. Alternatively, recalculate LRC on data and compare.

Modbus ASCII uses LRC on the binary values (not ASCII representation) of the message bytes. The LRC is then transmitted as two ASCII hex characters.

BCC (Block Check Character) is often used interchangeably with LRC, though some protocols define BCC as simple XOR without two's complement.

Yes. All computation happens in your browser using JavaScript. Your data never leaves your device.

Related Tools