Ethernet FCS order
Ethernet appends the 32-bit CRC as four FCS octets in least-significant-byte-first order, so the byte sequence may look reversed from the displayed hex value.
Network utility
Ethernet CRC and FCS Calculator
Calculate Ethernet CRC-32, view the transmitted FCS byte order, and validate captured frame trailers from hex bytes or plain text input.
- Runtime
- Browser
- CRC
- 32-bit
- Poly
- 04C11DB7
Frame input
Ethernet CRC uses init FFFFFFFF, reflected input, and final XOR FFFFFFFF.
Input format
0 bytes
CRC calculated.
CRC result
FCS bytes are shown in the order they appear at the end of an Ethernet frame.
Byte preview
Shows the first parsed bytes used for CRC calculation.
| Offset | Hex | Decimal | ASCII |
|---|
What to include
Calculate over the destination MAC through payload and padding. Do not include preamble, SFD, inter-frame gap, or the FCS itself unless validating a captured trailer.
Validation mode
When trailing FCS is enabled, the last four parsed bytes are treated as captured FCS and compared against the CRC calculated from the preceding bytes.
Usage guide
How to use the Ethernet CRC calculator
Hex input
Paste bytes as spaces, colons, commas, 0x-prefixed values, or a continuous hex string. The parser normalizes them before calculating CRC.
Text input
Switch to text mode to calculate the Ethernet-style CRC-32 of UTF-8 text, useful for checking known vectors or small payload examples.
Captured frames
Enable trailing FCS when a capture includes four checksum bytes at the end, then compare captured and expected FCS values.