CRC16 (Cyclic Redundancy Check 16-bit) is an error-detecting code commonly used in digital networks and storage devices to detect accidental changes to raw data. It produces a 16-bit checksum.

How do I calculate Modbus CRC16?

Select 'CRC-16/MODBUS' from the preset dropdown in our tool. Enter your data in Hex or ASCII format, and the calculator will instantly generate the correct checksum using the polynomial 0x8005 and initial value 0xFFFF.

What is the difference between CRC-16/CCITT and CRC-16/Modbus?

They use different polynomials and initialization values. Modbus uses 0x8005 with 0xFFFF init, while CCITT typically uses 0x1021 with 0xFFFF or 0x0000 init depending on the specific variant (False, Kermit, XModem).

CRC16 Calculator Hex | Online Modbus & Universal CRC Tool

Input Data

HEX ASCII

0 bytes

Configuration

Algorithm Preset

Polynomial (Hex)

Initial Value (Hex)

XOR Out (Hex)

Reflect Input

Reflect Output

Result

HEX (Big Endian)

0000

HEX (Little Endian)

0000

Decimal

Binary

00000000 00000000

About CRC16 Calculator Hex

The CRC16 Calculator Hex is a professional-grade tool designed for developers, engineers, and network administrators. It allows you to verify data integrity by calculating the 16-bit Cyclic Redundancy Check (CRC) checksum for any given input. Whether you are working with Modbus, XModem, or custom serial protocols, this tool provides accurate results instantly.

Why Use This Tool?

Universal Support: Pre-configured with over 20 common algorithms including Modbus, CCITT, and USB.
Customizable: Fully adjustable polynomial, initialization, and reflection parameters for custom protocols.
Privacy Focused: All calculations happen 100% in your browser. No data is sent to any server.
Developer Friendly: Share your exact configuration with teammates using the "Share Configuration" permalink feature.

How to Use

Select Input Type: Choose between HEX (for raw byte data) or ASCII (for text strings).
Enter Data: Type or paste your data into the input field. The tool ignores spaces in Hex mode.
Choose Algorithm: Select a preset like "CRC-16/MODBUS" from the dropdown.
View Results: The calculated CRC is displayed immediately in Hex (Big/Little Endian), Decimal, and Binary formats.

Common CRC16 Algorithms

Name	Poly	Init	Check (123456789)
CRC-16/MODBUS	0x8005	0xFFFF	0x4B37
CRC-16/CCITT-FALSE	0x1021	0xFFFF	0x29B1
CRC-16/XMODEM	0x1021	0x0000	0x31C3

Frequently Asked Questions

What is the difference between Big Endian and Little Endian? +

Big Endian stores the most significant byte first (e.g., 0x1234 becomes 12 34). Little Endian stores the least significant byte first (e.g., 0x1234 becomes 34 12). Modbus typically uses Little Endian for the CRC appended to the message.

Can I calculate CRC for Modbus RTU? +

Yes! Select the "CRC-16/MODBUS" preset. This is the standard algorithm used for Modbus RTU error checking.

Is my data safe? +

Absolutely. This tool runs entirely in your web browser using JavaScript. No data is ever sent to a server, ensuring your sensitive hex strings remain private.

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