Your DXF came out the wrong size. Here is why

2 Sept 2026 · 7 min read · DXF CAD Laser

A DXF has no pixels in it, so a converter that thinks in pixels has to guess. Most guess 1 unit per pixel, and a 2000px logo arrives two metres wide.

A DXF carries units, or it carries nothing

A DXF file stores coordinates as numbers. Whether those numbers mean millimetres, inches or something else is decided by one header variable, $INSUNITS. Set it to 4 and the file is millimetres. Set it to 1 and it is inches. Leave it out and every program that opens the file falls back to its own default, which is why the same DXF comes in at one size in LightBurn and another in Fusion.

A tracer that starts from a bitmap has no idea how big anything is. A 2000 pixel wide logo is 2000 pixels wide and nothing more. So the converter has to be told, and if it is not, it picks something. One unit per pixel is the common pick, and that is how you end up with a part two metres across.

What to check, in order

  • Open the DXF in a text editor and search for $INSUNITS. If it is not there, the file does not say what its numbers mean.
  • Measure a feature you know. A 100mm square should read 100, not 3.94 and not 283.
  • Check the extents. A part whose bounding box is 2834 x 2834 was written at 72 units per inch, which is a pixel scale wearing a unit label.
Veconvert writes $INSUNITS on every DXF and asks for an output width before it writes one. Set 200mm and the part measures 200mm in the program you open it in.

Why "scale it after" is not the fix

Scaling in the cutting software works, once, for one part. It stops working the moment you have a job with several files in it, because now every one of them has its own wrong scale and you are correcting each by hand. It also stops working the moment somebody else opens the file.

Worse, scaling after the fact does not fix kerf. If you offset the path for a 0.2mm laser beam and then scale the whole thing by 3.94, the offset scales too, and it is now 0.79mm on a beam that is still 0.2. The part fits nothing.

The short version

Export at the size the part is meant to be, from something that writes real units, and check one known dimension before you cut. Sixty seconds of measuring is cheaper than a sheet of 3mm ply.

Try it on your own file

Everything described here runs in your browser. Nothing is uploaded, and the conversion is free and unlimited.

Convert something

Related

Kerf: why your laser-cut part is always a bit too small A cutter removes material. If the tool runs down the middle of your line, the part finishes one tool width undersize and the hole finishes one tool width oversize. Here is the arithmetic. 28 Aug 2026 · 8 min read Colour, mono or centerline: which trace you actually want Three modes that produce three completely different files from the same image, and picking the wrong one is why the result looked nothing like what you expected. 6 Aug 2026 · 7 min read Cut the holes first, or the part moves The order a machine cuts in is not cosmetic. Cut the outline before the holes and the part drops, tilts or shifts, and everything after that is wrong. 29 Jul 2026 · 5 min read