CRC Calculator

Compute 8/16/32-bit CRCs (IBM, CCITT, MODBUS, XMODEM, MAXIM, Castagnoli) and NMEA XOR with step-by-step option.

Input data

13 bytes

Variant	HEX	DEC	BIN
CRC-8 poly=0x07 init=0x00 refIn=false refOut=false xorOut=0x00	0xBC	188	10111100
CRC-8/MAXIM poly=0x31 init=0x00 refIn=true refOut=true xorOut=0x00	0x2A	42	00101010
CRC-16/IBM (ARC) poly=0x8005 init=0x0000 refIn=true refOut=true xorOut=0x0000	0x9A4A	39498	1001101001001010
CRC-16/CCITT-FALSE poly=0x1021 init=0xFFFF refIn=false refOut=false xorOut=0x0000	0x52D2	21202	0101001011010010
CRC-16/MODBUS poly=0x8005 init=0xFFFF refIn=true refOut=true xorOut=0x0000	0x7149	29001	0111000101001001
CRC-16/XMODEM poly=0x1021 init=0x0000 refIn=false refOut=false xorOut=0x0000	0x7ADE	31454	0111101011011110
CRC-32 (PKZip / Ethernet) poly=0x04C11DB7 init=0xFFFFFFFF refIn=true refOut=true xorOut=0xFFFFFFFF	0xEBE6C6E6	3957769958	11101011111001101100011011100110
CRC-32C (Castagnoli) poly=0x1EDC6F41 init=0xFFFFFFFF refIn=true refOut=true xorOut=0xFFFFFFFF	0xC8A106E5	3365996261	11001000101000010000011011100101
XOR checksum (NMEA 0183) XOR over all bytes	0x0D	13	00001101

Show step-by-step CRC-8 calculation

Batch mode (one input per line)

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About CRC Calculator

The CRC Calculator computes cyclic redundancy checks and checksums from ASCII text or raw hex bytes, showing each result in hexadecimal, decimal, and binary at once. It covers eight standard variants, including CRC-8, CRC-8/MAXIM, CRC-16/IBM, CRC-16/CCITT, CRC-16/MODBUS, CRC-16/XMODEM, CRC-32, and CRC-32C (Castagnoli), plus the NMEA 0183 XOR checksum used in marine sentences. It solves the everyday problem of verifying frame integrity without writing throwaway code.

It is built for embedded developers, Modbus and serial protocol engineers, and marine electronics integrators working with NMEA data. An optional step-by-step CRC-8 view exposes the register state byte by byte, and batch mode handles many lines at once. It is free and runs entirely in your browser, so your payloads never leave your machine.

How to use

Choose ASCII or HEX for the type of input you are pasting.
Type or paste your data into the input box.
Read the CRC-8, CRC-16, CRC-32, and NMEA XOR results in hex, decimal, and binary.
Tick 'Show step-by-step' to inspect the CRC-8 register after each byte.
Open Batch mode to process one input per line at once.
Use 'Copy all' to export every variant as CSV.

Features

Eight CRC variants plus NMEA XOR
ASCII and raw hex input modes
Hex, decimal, and binary output
Step-by-step CRC-8 register trace
Batch mode for many inputs
Shows each variant's polynomial parameters

Frequently asked questions

Is my input sent anywhere?

No. Every calculation happens locally in your browser, so the data you paste is never uploaded or stored on a server. The tool is free and works offline once loaded.

Which CRC variants are supported?

CRC-8, CRC-8/MAXIM, CRC-16/IBM (ARC), CRC-16/CCITT-FALSE, CRC-16/MODBUS, CRC-16/XMODEM, CRC-32 (PKZip/Ethernet), and CRC-32C (Castagnoli), along with the NMEA 0183 XOR checksum.

How do I check an NMEA 0183 sentence checksum?

Paste the characters between the '$' and '*' in ASCII mode and compare the XOR checksum row against the two hex digits after the asterisk in the sentence.

Can I enter raw bytes instead of text?

Yes. Switch to HEX mode and enter byte values like '48 65 6C'; spaces and 0x prefixes are ignored, but the digit count must be even.

Why is the step-by-step view limited to CRC-8?

The trace walks through the 8-bit register's XOR and shifts for each byte, which is the clearest variant for learning how CRCs work. Final results for all variants still appear in the table.

Related tools

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AIS Message Encoder

Build a valid AIS Type 1 position report from form inputs with step-by-step encoding.

NMEA 0183 Sentence Parser

Auto-detect and decode 17+ NMEA 0183 sentence types with checksum validation.

Variant

HEX

DEC

BIN

CRC-8

poly=0x07 init=0x00 refIn=false refOut=false xorOut=0x00

0xBC

188

10111100

CRC-8/MAXIM

poly=0x31 init=0x00 refIn=true refOut=true xorOut=0x00

0x2A

00101010

CRC-16/IBM (ARC)

poly=0x8005 init=0x0000 refIn=true refOut=true xorOut=0x0000

0x9A4A

39498

1001101001001010

CRC-16/CCITT-FALSE

poly=0x1021 init=0xFFFF refIn=false refOut=false xorOut=0x0000

0x52D2

21202

0101001011010010

CRC-16/MODBUS

poly=0x8005 init=0xFFFF refIn=true refOut=true xorOut=0x0000

0x7149

29001

0111000101001001

CRC-16/XMODEM

poly=0x1021 init=0x0000 refIn=false refOut=false xorOut=0x0000

0x7ADE

31454

0111101011011110

CRC-32 (PKZip / Ethernet)

poly=0x04C11DB7 init=0xFFFFFFFF refIn=true refOut=true xorOut=0xFFFFFFFF

0xEBE6C6E6

3957769958

11101011111001101100011011100110

CRC-32C (Castagnoli)

poly=0x1EDC6F41 init=0xFFFFFFFF refIn=true refOut=true xorOut=0xFFFFFFFF

0xC8A106E5

3365996261

11001000101000010000011011100101

XOR checksum (NMEA 0183)

XOR over all bytes

0x0D

00001101

About CRC Calculator

How to use

Choose ASCII or HEX for the type of input you are pasting.

Type or paste your data into the input box.

Read the CRC-8, CRC-16, CRC-32, and NMEA XOR results in hex, decimal, and binary.

Tick 'Show step-by-step' to inspect the CRC-8 register after each byte.

Open Batch mode to process one input per line at once.

Use 'Copy all' to export every variant as CSV.