When the PDF is all you have
Every project eventually hands you a sheet with no CAD file behind it: an existing-conditions survey from a permit set that is a decade old, a consultant's utility plan, a municipal standard detail, or a record drawing pulled from the town's archive. Redrawing it by hand eats a day and invites transcription errors. If the PDF was plotted from CAD, the linework is still inside it as vectors, and converting the PDF to DXF gets it back.
First, check that it's a vector PDF and not a scan
Zoom far into a line. In a vector PDF the line stays crisp at any zoom; in a scan it turns soft and blocky, because a scan is a photograph of the paper. Only vector content converts to CAD geometry, and this tool tells you when a sheet is raster-only rather than handing you an empty file. Many plan sets mix the two, with a vector title block wrapped around a scanned drawing.
What comes through in the DXF
PDF layers become DXF layers
AutoCAD, Civil 3D, and MicroStation can write their layers into the PDF as optional content, and usually do by default. The converter maps each one to a DXF layer of the same name and switches off the ones that were hidden, so you can freeze the topo and keep the property lines without sorting thousands of entities by color.
Arcs, circles, and curves
CAD programs write arcs into a PDF as Bezier curves that sit exactly on a circle. The converter recognizes them and writes true arcs and circles back out, so a curb return still has a radius and a manhole still has a center you can snap to. Curves that aren't circular, like splines and contours, are flattened to within about 0.0007 inch on paper.
Text and scale
Selectable text becomes TEXT entities on a PDF-TEXT layer, at its original size and rotation. Text the CAD program drew as strokes, which is common with SHX fonts, arrives as linework. Choose the scale printed on the sheet and the DXF is written in real-world feet, inches, meters, or millimeters; leave it unset and you get paper inches.
Use case: sending a redline back to the drafter as linework
Say you're reviewing a site plan and the curb line along the drive aisle needs to move two feet to clear a light pole. The usual handoff is a cloud on a PDF and a note, and the drafter redraws it by eye. Converting the reviewed sheet to DXF at 1" = 20' gives the drafter the same geometry you were looking at, in feet, on the original layers, ready to XREF under the design file and check against. In Vellum you can go one step further: draft the revised curb line on the sheet with typed lengths and offsets, then export only your markups as DXF so the change arrives as linework.
Tips for a clean PDF to CAD handoff
- Attach the DXF as an XREF rather than inserting it, so the converted sheet stays a reference and never mixes with design linework.
- Measure a dimensioned line in CAD after converting. If it is off by a constant factor, the PDF was resized when it was printed: scale the reference by that factor.
- Freeze what you don't need before anything else. Hatching, title blocks, and annotation layers are usually the noise.
- Treat converted geometry as a record of the sheet, not a survey. Confirm critical dimensions against the source before you design from them.