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Checksum Calculator (CRC16 / CRC32)

Calculate CRC-16, CRC-32, Adler-32, and Sum-8 checksums from text in one click.

Input data is processed in your browser
Data is never sent to a server

Tool

0 chars

or drag & drop a file

What is a Checksum?

A checksum is a short value derived from data to verify its integrity. It is used across data transfer, file storage, and communication protocols to detect whether data has been corrupted or altered.

Common Use Cases by Algorithm

  • CRC-16/CCITT: Bluetooth, ITU-T V.41, SD cards
  • CRC-16/IBM: USB, Modbus, serial communication
  • CRC-32: ZIP, Ethernet, PNG, zlib
  • Adler-32: zlib (PNG, HTTP gzip)
  • Sum-8: Simple integrity checks, embedded systems

How to Use

  1. Enter the text you want to checksum into the input field.
  2. Choose an output format (uppercase hex, lowercase hex, or decimal).
  3. Click "Calculate" to see all algorithm results at once.
  4. Copy individual values with the row copy button, or use "Copy All" to copy everything.

FAQ

What is the difference between CRC-16 and CRC-32?

CRC-16 produces a 16-bit output (4 hex digits), while CRC-32 produces a 32-bit output (8 hex digits). CRC-32 has a lower collision probability and is used in many standards including ZIP, Ethernet, and PNG. CRC-16 is common in serial communication and storage protocols.

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

They use different polynomials and computation methods. CRC-16/CCITT (0x1021) is used in ITU-T V.41 and Bluetooth, while CRC-16/IBM (0x8005) is used in USB and Modbus. Choose the variant appropriate for your target protocol.

What is Adler-32?

Adler-32 is a 32-bit checksum algorithm designed by Mark Adler, used in the zlib library (PNG and HTTP compression). It is faster to compute than CRC-32, but has slightly weaker collision resistance for short inputs.

Is any data sent to the server?

No. All calculations are performed locally in your browser using JavaScript. Your input is never transmitted to any server.

Can I calculate checksums for files?

The current tool supports text input. For file checksum verification, we recommend using OS command-line tools such as md5sum, sha256sum, or cksum.

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