NMEA 2000 PGN Decoder

Parse the 29-bit CAN identifier and decode 15+ common PGNs (heading, GPS, wind, engine, tanks, environment).

N2K frame (CAN ID + payload, in hex)

First 4 bytes are the 29-bit CAN identifier (big-endian), remaining bytes are the data payload.

Reference: PGNs this tool fully decodes

PGN	Name
127250	Vessel Heading
127251	Rate of Turn
127257	Attitude
127258	Magnetic Variation
127488	Engine Parameters — Rapid Update
127489	Engine Parameters — Dynamic
127505	Fluid Level
128259	Speed (water-referenced)
128267	Water Depth
129025	Position — Rapid Update
129026	COG & SOG — Rapid Update
129029	GNSS Position Data
130306	Wind Data
130310	Environmental Parameters (legacy)
130311	Environmental Parameters

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About NMEA 2000 PGN Decoder

The NMEA 2000 PGN Decoder takes a raw N2K message and breaks it down for you. It parses the 29-bit CAN identifier into its parts (priority, PGN, source and destination addresses) and decodes the data payload for 15+ common parameter group numbers, including heading, GPS position, wind, engine parameters, fluid tank levels, and environmental readings. Instead of staring at hex bytes, you see labeled, human-readable fields.

It is built for marine electronics installers, boat builders, NMEA 2000 developers, and DIY sailors troubleshooting a backbone or sniffer log. It is free and runs entirely in your browser, so the messages you paste from your gateway or analyzer never leave your machine and nothing is uploaded to a server.

How to use

Paste a raw NMEA 2000 frame or CAN identifier into the input box.
Let the tool split the 29-bit identifier into priority, PGN, and addresses.
Read the decoded payload fields for the matched PGN below.
Check the source and destination addresses to confirm which device sent the message.
Edit or paste another frame to decode the next message.

Features

Splits the 29-bit CAN identifier into fields
Decodes 15+ common marine PGNs
Covers heading, GPS, wind, and engine data
Reads fluid tank and environmental PGNs
Runs fully client-side in your browser
Free with no upload or sign-up

Frequently asked questions

Does my NMEA 2000 data get uploaded anywhere?

No. All parsing happens locally in your browser, so frames from your gateway or log stay on your device and are never sent to a server.

Which PGNs can this tool decode?

It handles 15+ of the most common parameter group numbers, spanning heading, GPS position, wind, engine parameters, fluid tank levels, and environmental measurements. Less common or proprietary PGNs may not be recognized.

What does the 29-bit identifier contain?

The extended CAN identifier encodes the message priority, the PGN itself, and the source and destination addresses. The tool separates these so you can see who sent the frame and what type it is.

Is it really free to use?

Yes, the decoder is completely free with no account or sign-up required, and you can decode as many frames as you like.

Can it decode multi-frame fast-packet messages?

It focuses on decoding the listed common PGNs from the frames you provide. For PGNs that span multiple frames, make sure the full message bytes are pasted together so the payload can be read correctly.

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PGN

Name

127250

Vessel Heading

127251

Rate of Turn

127257

Attitude

127258

Magnetic Variation

127488

Engine Parameters — Rapid Update

127489

Engine Parameters — Dynamic

127505

Fluid Level

128259

Speed (water-referenced)

128267

Water Depth

129025

Position — Rapid Update

129026

COG & SOG — Rapid Update

129029

GNSS Position Data

130306

Wind Data

130310

Environmental Parameters (legacy)

130311

Environmental Parameters

About NMEA 2000 PGN Decoder

How to use

Paste a raw NMEA 2000 frame or CAN identifier into the input box.

Let the tool split the 29-bit identifier into priority, PGN, and addresses.

Read the decoded payload fields for the matched PGN below.

Check the source and destination addresses to confirm which device sent the message.

Edit or paste another frame to decode the next message.