Checksum Calculator (BCC / LRC / CRC)

Free online checksum calculator: compute BCC (XOR), LRC, CRC8, CRC16/MODBUS, CRC16/CCITT-FALSE and CRC32 in one click. Text or hex input. Runs in your browser.

Runs locally · data never uploaded
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How to use

What it does

Checksums are widely used for error detection in communication and storage. This tool computes several common algorithms at once: BCC (XOR of all bytes), LRC (longitudinal redundancy check, 256 minus the sum of bytes), and the CRC family — CRC8, CRC16/MODBUS, CRC16/CCITT-FALSE and CRC32.

Two input modes are supported: UTF-8 text or a hex string (e.g. 48 65 6c 6c 6f). In hex mode each byte is two digits and spaces are allowed. Results are shown in hex and can be toggled between upper and lower case.

Example

Input the text 123456789 (UTF-8) with "UTF-8 text" selected:

BCC:           15
LRC:           E6
CRC8:          19
CRC16/MODBUS:  4B37
CRC16/CCITT:   29B1
CRC32:         E3069283

This is the canonical CRC check vector, handy for verifying an implementation.

FAQ

Q1.What is the difference between BCC and LRC?
BCC XORs every byte together into a single byte. LRC sums all bytes and takes the two's complement modulo 256, also a single byte — commonly seen in protocols like Modbus ASCII.
Q2.Are CRC16/MODBUS and CRC16/CCITT the same?
No. They differ in polynomial and initial value: MODBUS uses 0xA001 (reflected) with init 0xFFFF, while CCITT-FALSE uses 0x1021 with init 0xFFFF and no reflection. The same data yields different results.
Q3.How do I write hex input?
Write the hex bytes continuously or space-separated, e.g. `48 65 6c 6c 6f` for "hello". Any character outside 0-9 / a-f triggers an error message.
Q4.Is my data uploaded?
No. All computation happens in your browser and keeps working offline; nothing you enter leaves your device.
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