Free online NMEA to CSV converter

GPS and marine-navigation software often records position data as NMEA sentences, while spreadsheets, databases, and GIS tools generally expect CSV rows and columns. Converting the file makes timestamps, coordinates, speed, course, and fix data easier to filter, edit, archive, or import.

What the NMEA format is

NMEA usually refers to NMEA 0183, a plain-text protocol used by GPS receivers, chartplotters, autopilots, surveying equipment, and navigation applications. A file may use .nmea, .log, or .txt as its extension.

Each record is a sentence beginning with a talker and sentence identifier, such as $GPGGA for a GPS fix or $GPRMC for recommended minimum navigation data. Fields are comma-separated, but different sentence types contain different fields; the file is therefore not automatically a consistent spreadsheet table.

What the CSV format is

CSV stores tabular data as rows and delimiter-separated fields. Spreadsheet programs such as LibreOffice Calc and Microsoft Excel, database tools, scripts, and GIS applications can import it without requiring navigation-specific software.

A converted file can contain normalized columns such as timestamp, latitude, longitude, altitude, speed, course, fix quality, and satellite count. CSV has no built-in definition for coordinate systems, units, date formats, or column types, so the conversion tool must determine how NMEA fields are represented.

How to actually convert NMEA to CSV

Using GPSBabel

GPSBabel is suitable for converting standard NMEA track and waypoint data from the command line. Install it, place the source file in the working folder, and run:

gpsbabel -i nmea -f input.nmea -o unicsv -F output.csv

Replace input.nmea with the actual filename. The unicsv output format produces a general-purpose CSV file that can be opened in LibreOffice Calc or another spreadsheet application.

For a graphical workflow, open the GPSBabel interface, select Input format → NMEA 0183 data, choose the source file, select Output format → Universal CSV, specify the destination filename, and start the conversion.

Using the online converter

You can convert the file for free on 101convert.com without installing software. Upload the NMEA file, select CSV as the output format, start the conversion, and download the resulting file.

Quality and compatibility limits

NMEA files can contain several sentence types, including standard, device-specific, and vendor-proprietary records. A converter may ignore unsupported sentences, so compare the source and output when altitude, satellite data, signal quality, or proprietary measurements matter.

Latitude and longitude in NMEA commonly use degrees and decimal minutes, such as 4807.038,N, rather than decimal degrees. Confirm that the converter changes these values correctly; a spreadsheet import must not treat them as ordinary decimal-degree coordinates.

NMEA timestamps are normally UTC, and a CSV file does not preserve timezone metadata unless the converter adds it to a column or filename. Check the date, time, coordinate order, hemisphere signs, altitude units, speed units, and CSV delimiter before importing the result into GIS or analysis software.

Raw NMEA files are already plain text, so CSV conversion generally improves structure and compatibility rather than reducing file size. Preserve the original file because CSV cannot retain every sentence, checksum, device message, or transmission detail.