CRC Value Calculator

Work out crc value instantly with clear inputs, formula shown and shareable results.

About CRC Value Calculator

A CRC treats the message as a polynomial over GF(2) and returns the remainder after division by a generator polynomial. That algebraic structure guarantees detection of all burst errors shorter than the CRC width, which is why CRCs are used in Ethernet, USB and storage. It also makes them linear and therefore trivially forgeable, so a CRC is never a security control.

Formula

CRC computation

CRC = message polynomial mod generator polynomial over GF(2); CRC-32 uses reflected 0xEDB88320 with initial and final XOR of 0xFFFFFFFF

Worked example

With the default values below, CRC Value Calculator returns CRC value of 0xCBF43926. Change any input above and every figure here is recalculated in your browser.

Inputs used

Data bytes in hex: 313233343536373839
CRC variantone of CRC-8 (polynomial 0x07), CRC-16-CCITT (0x1021), CRC-32 (0x04C11DB7, reflected): CRC-32 (0x04C11DB7, reflected)

Results

CRC value: 0xCBF43926
CRC width: 32 bits
Shortest burst error that can slip through: 33 bits
Detection properties: Detects all burst errors up to 32 bits and all single and double bit errors, but offers no protection against deliberate tampering

Step by step

1Values used
2CRC computation
3CRC value= 0xCBF43926
4CRC width= 32 bits
5Shortest burst error that can slip through= 33 bits
6Detection properties= Detects all burst errors up to 32 bits and all single and double bit errors, but offers no protection against deliberate tampering

Assumptions and limits

The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why can a CRC not be used for security?

It is linear: CRC(a XOR b) = CRC(a) XOR CRC(b). An attacker can modify a message and adjust the CRC to match without any secret.

Which CRC variant is in Ethernet?

CRC-32 with the reflected 0xEDB88320 polynomial, the same variant computed here, appended as the frame check sequence.