Open a GEF File and Convert It to Excel, CSV or AGS

You receive a GEF file — from a CPT contractor, from the project archive or via DINOloket, the Dutch public subsurface archive — but you want the data in Excel, or in another format for your own software. You don't need specialized geotechnical programs for that: it can be done for free in the browser, without your file being uploaded anywhere.

Opening a GEF file without special software

A GEF file is plain text, so technically you can open it in Notepad. That won't tell you much: you'll see header lines and columns of numbers, but no chart. A viewer that interprets the file is more useful. Drag the GEF file into the CPT Converter and you immediately see:

• the cone resistance (qc) per depth as a chart;
• the friction ratio (Rf), if the file contains friction data;
• an indicative soil profile according to the Robertson classification, with a legend of the soil types.

The metadata from the header (sounding number, coordinates, ground level) is picked up automatically, so you don't have to retype it.

Converting to Excel or CSV

After loading, you choose the desired format via the Download button:

• Excel (.xlsx) – a workbook with a data sheet (depth, qc and, where available, fs and Rf) and a separate sheet with the metadata. Handy for your own calculations or reports.
• CSV – semicolon-separated text that any program can read, from Excel to Python and Matlab.
• JSON – structured data for your own scripts and tools.

International exchange: AGS4

If you work with international parties, GEF is often unknown: outside the Netherlands, AGS (Association of Geotechnical & Geoenvironmental Specialists) is the common standard, including in the United Kingdom. The converter exports a loaded GEF file directly as an AGS4 file with the SCPT group (CPT data) and the associated project and location details.

And the other way round: from scan to GEF

If all you have is a PDF or scan of the CPT sounding, there is no data to convert — it has to be digitized first. That can be done in the same tool: calibrate the axes and trace the qc line automatically. How that works is explained in the step-by-step guide to digitizing a CPT sounding.

Privacy: your data stays local

All processing — reading, displaying, converting — happens in your own browser. The GEF file is never sent to a server. That also makes the tool suitable for confidential project data.