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How to turn a PDF into an STL

A PDF holds a picture of a page. It has no thickness, no solid, and usually no way of knowing what one unit on it means. What it often does hold is outlines — and outlines can be given a thickness, which is probably what you are after. The route is one extra step.

We do not read PDF. Getting the outlines out of one needs a page-layout engine, and the result depends so much on how the PDF was made that a button here would work for some files and silently produce nonsense for others. Exporting an SVG or a DXF takes a few seconds and gives you something you can check.

Getting outlines out of a PDF

Which of these applies depends on what the PDF actually is. Check that first: zoom in a long way in your PDF viewer. If the edges stay perfectly crisp, it holds real outlines and the first two routes work. If they go blocky, it holds a photograph of a drawing and only the last one does.

  1. Best: go back to the program that made it

    A PDF is almost always exported from something else — a CAD program, Illustrator, Inkscape, a laser-cutting file. Whatever made it can also export an SVG or a DXF, and that file will be exact rather than reconstructed.

    This is worth a message to whoever sent you the PDF. It takes them ten seconds and saves you all of the steps below.

  2. Open the PDF in Inkscape

    File → Open → (choose Internal import)

    Inkscape is free and reads PDF directly. Choose the internal import when it asks, which keeps the outlines as paths instead of turning the page into an image.

    If the drawing comes in as one big clipped group, select it and use Object → Clip → Release, then delete the page rectangle.

  3. Turn any text into paths

    Path → Object to Path

    Letters in a PDF are still text, and a font cannot travel into an SVG. Select everything and convert it, or the lettering will vanish later.

  4. Set the document size to the real size

    File → Document Properties → Resize to content

    Then check one known dimension against the real part. A PDF page is measured in points, and a drawing placed on it at some scale carries no record of that scale.

  5. Save as Plain SVG, or export a DXF

    File → Save As → Plain SVG

    Either works here. Choose DXF if the part is going to a laser cutter or a CNC machine, because a DXF states its units outright.

  6. If the PDF is a scan, trace it instead

    Path → Trace Bitmap

    A scanned or photographed drawing has no outlines in it, only pixels. Inkscape’s trace turns the dark areas into paths. The result follows the ink, including every wobble and speck, so clean it up before using it.

The two completely different things people mean by this

A flat drawing to be given a thickness. A logo, a sign, a gasket, a bracket profile, a part to be laser cut. This is the common case and it works well: get the outlines out as SVG or DXF, drop them here, set a thickness, done.

A 3D model that happens to have been sent as a PDF. Some CAD programs export a 3D PDF, which really does hold geometry — you can rotate the model inside Acrobat. That geometry cannot be extracted by anything except the program that made it, or by Acrobat Pro. Ask the sender for a STEP file, which every CAD program can export and this site reads properly.

If you can rotate the model in your PDF viewer, you have the second kind. If it is a flat page, you have the first.

The scale problem, which is the real risk here

A PDF page is measured in points, seventy-two to the inch, and a drawing placed on that page was scaled by whoever placed it. Nothing in the file records that scale. So a drawing that says "100 mm" in a dimension line may occupy 38 mm of the page, or 200 mm, and there is no way to tell from the file alone.

This is why there is no button here. A converter that read the PDF and gave you a model would be guessing at the scale, and you would not find out it guessed wrong until after the material was cut.

Whatever route you take, check one known dimension against the real thing before you print or cut. The converters here show the width and depth in millimetres beside the model, and the scale box corrects them.

When the drawing has dimension lines but no outlines

A great many engineering PDFs are drawings *of* a part: three views, dimension lines, tolerances, a title block. The outlines in them are views rather than a profile, and extruding a front view gives you something that is not the part.

In that case the PDF is a specification, not a model, and the work is to model the part from it. There is no shortcut: read the dimensions and draw it in a CAD program. FreeCAD and Onshape are both free and both export STEP, which this site converts.

Where we can actually help

Once the outlines are out as an SVG or a DXF, this is where they become a solid. Set the thickness and watch the measurements before you download.

Questions

Is there an online tool that converts PDF to STL in one step?
Several claim to. What they do is trace the page and extrude the result, at a scale they have guessed. For a logo that is fine; for anything that has to fit something, it is a part that comes out the wrong size. The extra step here exists so that you see the drawing at a size you can check before it becomes a solid.
How do I tell whether my PDF has real outlines?
Zoom in a long way in your PDF viewer. Real outlines stay perfectly crisp at any zoom. A scan or a photograph goes blocky. That one test decides which route above applies.
My PDF is a 3D PDF and I can rotate the model. Can I get that out?
Not with free software. The geometry is embedded in a form only Acrobat and the program that made it can read. Ask the sender for a STEP file — every CAD program exports one and this site reads it properly, keeping the exact curved surfaces.
The text in my drawing disappeared.
Text is not an outline, and a font cannot travel into an SVG or a DXF. Convert the text to paths before saving — Path → Object to Path in Inkscape, Type → Create Outlines in Illustrator.

Where to go next

Related guides

Tools that do part of this here

About these formats

Checked against current software versions on 2026-09-13