CPT Converter

Digitize a CPT sounding from a scan and export it to GEF

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Drop a CPT sounding here or click to browse

Scan (JPG, PNG, TIFF, PDF) or GEF file · or paste an image with Ctrl+V

How it works

  1. Load a scan of the sounding (JPG, PNG, TIFF or PDF) or paste with Ctrl+V.
  2. Calibrate the axes automatically or click two known points per axis.
  3. Digitize the cone resistance line with Auto-trace or click it manually.
  4. Fill in the metadata and download the file in your preferred format.

You can also load an existing GEF file: you will immediately see the charts and the Robertson soil profile, and you can export to other formats.

Everything runs locally in your browser: your sounding is never uploaded, unless you deliberately save it to your account. Want to know more? Read how to digitize an old CPT sounding to GEF.

Frequently asked questions

What is a GEF file?

GEF (Geotechnical Exchange Format) is the Dutch standard for exchanging geotechnical site investigation data such as cone penetration tests (CPT). Virtually all geotechnical software, such as D-Foundations, can read GEF files.

How do I convert a PDF or scan of a CPT sounding to GEF?

Load the scan (PDF, JPG, PNG or TIFF) into the converter, calibrate the axes (automatically or with two clicks per axis) and trace the cone resistance line with Auto-trace. Then download the result as a GEF file.

Is CPT Converter free?

Yes, the converter is completely free to use, with no installation or registration. An account is only needed if you want to store soundings online.

Is my sounding uploaded anywhere?

No. All processing happens locally in your browser; your file never leaves your computer. Only if you explicitly choose "Save to my account" is the sounding stored in the cloud.

Which export formats are supported?

GEF (Dutch standard), CSV, Excel (.xlsx), JSON, AGS4 (international standard) and the chart as PNG, JPG or PDF. A loaded GEF file can therefore also be converted to Excel or AGS4.

How accurate is the digitization?

Accuracy depends on scan quality. With a clean scan and a readable grid, the deviation is usually within the thickness of the drawn line. You can drag any point afterwards and check the result directly in the chart view.