Other Tools
CRC Calculator – CRC-8, CRC-16 and CRC-32
Calculate CRC checksums from text or hexadecimal bytes with standard CRC-8, CRC-16, CRC-32 and CRC-32C profiles.
CRC result
CRC-32/ISO-HDLC · 9 bytes
Online CRC Calculator for Text and Hex Data
This calculator generates cyclic redundancy check values from UTF-8 text or raw hexadecimal bytes. Choose a named profile instead of only choosing a bit width: the polynomial, initial value, reflection settings and final XOR must all match the system that produced the expected checksum.
Supported CRC profiles
| Profile | Width | Typical use |
|---|---|---|
| CRC-8/SMBUS | 8 bit | SMBus and compact data checks |
| CRC-8/MAXIM-DOW | 8 bit | Dallas/Maxim 1-Wire devices |
| CRC-16/ARC | 16 bit | General archived and legacy data |
| CRC-16/CCITT-FALSE | 16 bit | Telecom and embedded protocols |
| CRC-16/MODBUS | 16 bit | Modbus RTU messages |
| CRC-16/XMODEM | 16 bit | XMODEM transfers |
| CRC-32/ISO-HDLC | 32 bit | ZIP, Ethernet and common file checks |
| CRC-32C/CASTAGNOLI | 32 bit | Storage and network protocols |
How to calculate a CRC
- Select the exact CRC profile required by your protocol or device.
- Choose Text / UTF-8 for normal text, or Hex bytes for packet data.
- Enter the data and select Calculate CRC.
- Copy the hexadecimal checksum, or compare the decimal and binary forms.
The example 123456789 is the standard check string used to verify CRC implementations. Each profile on this page is tested against its published check value.
Text input versus hexadecimal input
Text mode first encodes characters as UTF-8. Therefore non-ASCII characters can occupy more than one byte. Hex mode uses the exact bytes entered: 31 32 33 represents the ASCII bytes for 123. Hex bytes may be separated with spaces, commas, colons or hyphens.
CRC is an error check, not encryption
A CRC can detect many accidental transmission and storage errors, but it is not a cryptographic hash and provides no protection against intentional modification. Use a secure hash or message authentication code when authenticity matters.
Frequently asked questions
Why do two CRC calculators return different values?
They may use different profiles. Width alone is insufficient; compare Poly, Init, RefIn, RefOut and XorOut.
What is the difference between CRC-32 and CRC-32C?
They are both 32-bit checksums but use different polynomials. Their results are not interchangeable.
Is my data uploaded?
No. Encoding and checksum calculation run locally in your browser.