CRC32 / CRC16 Calculator
Calculate CRC-32, CRC-16/IBM, CRC-16/CCITT, and CRC-8 checksums from text or hex input.
What Is a CRC Checksum?
A Cyclic Redundancy Check (CRC) is an error-detection algorithm that produces a short fixed-length checksum from arbitrary data. It is widely used in network protocols, file formats (ZIP, PNG, Ethernet), and storage systems to detect accidental data corruption. CRC is not a cryptographic hash — it is designed for speed and error detection, not security. This tool computes CRC-32 (IEEE 802.3), CRC-16/IBM (Modbus), CRC-16/CCITT, and CRC-8 (Dallas/Maxim) from text or raw hex input.
How to Use
- Choose Text mode to enter a string — it is encoded as UTF-8 bytes
- Choose Hex mode to enter raw bytes as hex (e.g.
DE AD BE EF) - Results appear in hex, decimal, and binary for all four CRC variants
- Click any value to copy it
CRC Variants Explained
- CRC-32 (IEEE 802.3): used in Ethernet, ZIP, PNG, gzip. Polynomial 0x04C11DB7 (reflected).
- CRC-16/IBM (Modbus): used in Modbus RTU, USB. Polynomial 0x8005 reflected, init 0x0000.
- CRC-16/CCITT: used in Bluetooth, SD cards, X.25. Polynomial 0x1021 reflected, init 0xFFFF.
- CRC-8 (Dallas/Maxim): used in 1-Wire devices, DS18B20 temperature sensors. Polynomial 0x31 reflected.
FAQ
What is the difference between CRC and a hash like SHA-256?
CRC is designed for fast error detection in noisy channels — it catches random bit errors but is trivially reversible and easily collided intentionally. SHA-256 is a cryptographic hash designed to be computationally infeasible to reverse or collide. Use CRC for data integrity (accidental corruption), use SHA-256 for security (tamper detection).
Why does the same string give different CRC results in different tools?
CRC variants differ in initial value, final XOR value, bit reflection, and polynomial. Even the same algorithm name (e.g. "CRC-16") may refer to different configurations. Always specify the full variant name and parameters when communicating CRC checksums.
Can CRC detect all errors?
CRC-32 can detect all single-bit errors, all burst errors shorter than 32 bits, and most longer bursts. However, it is possible (though unlikely with random data) for two different inputs to produce the same CRC. For guaranteed integrity, use a cryptographic hash like SHA-256.
What is the Hex input mode for?
Hex mode lets you compute CRC over raw binary data that would be difficult to type as text. For example, protocol frames, sensor readings, or file headers specified as 0xDE 0xAD 0xBE 0xEF. Spaces, commas, and 0x prefixes are stripped automatically.