Laser cutter file formats: SVG, DXF, PDF, AI or .lbrn2?

What a laser file carries

Laser software needs five things from a file: geometry (lines, arcs, curves), units (how many millimeters or inches that is), a split into operations (colors or layers: what to cut, what to engrave), possibly text and an image to engrave — and, in a project file, the settings (power, speed, passes). No format carries all of it, and most trouble comes from what the file leaves out.

SVG — the best exchange format, if it has a unit

SVG is a text file of curves that almost every graphics and laser program opens. Its one trap is units. A size in millimeters (width="100mm") or inches (width="4in") is unambiguous. But many programs write only numbers “in pixels” — and how many pixels make an inch is something each program decides for itself:

• Inkscape and the CSS standard: 96 per inch. LightBurn reads SVG this way by default.
• Illustrator: writes points, 72 per inch. A program counting 96 per inch loads such a file at 75% size.
• Inkscape up to version 0.91: 90 per inch. An old file comes in at 93.75% — 100 mm becomes 93.75 mm (4″ becomes 3.75″), which is easy to miss.

LightBurn has a switch for this: Settings → Import/Export → SVG Import — 96 DPI (Inkscape) or 72 DPI (Illustrator). xTool has a similar field. Simpler still: save the file with real units. In Inkscape, set the document units to mm or inches (File → Document Properties); from Illustrator, export PDF or AI instead of SVG. The “what came out → scale by” table is in our post on laser cutting file mistakes.

Beyond units, SVG behaves predictably: curves stay curves (the laser software flattens them to segments at its own tolerance), the stroke color lands on a layer, and the program snaps it to the nearest palette color. Two things SVG won’t do for you: text is stored as a string plus a font name, so without that font on the computer the laser substitutes another or drops the text — convert to outlines before saving; and an image embedded in an SVG is still an image, not a cut line — it needs vectorizing.

DXF — numbers without units

DXF is the exchange format of CAD programs (AutoCAD, Fusion, FreeCAD, SolidWorks). It stores geometry as a list of entities — LINE, ARC, CIRCLE, polylines and splines — each on a named layer with a color from a numbered palette. Three things to know:

• Units are optional. The DXF header has a field for units ($INSUNITS: 0 = none, 1 = inches, 4 = millimeters), but many programs leave it empty. Then the file is just numbers, and the laser software guesses. LightBurn has an “Auto-detect units if possible” option plus a fallback unit for files it can’t identify; xTool’s DXF import settings include similar detection. Inches read as millimeters give a part 25.4 times too small — and the other way round. Always measure one known dimension after importing.
• The outline is usually in pieces. A rectangle from CAD is four separate lines, a rounded corner a separate arc. The laser cuts the pieces one by one, stopping at every end, and the part may not drop out if the ends don’t meet exactly. LightBurn and xTool both have an “auto-close tolerance” in their DXF import settings — the distance below which ends are joined into a closed contour. Best of all is to join them into a single closed polyline in CAD before exporting.
• A spline is not an arc. A circle stored as CIRCLE or ARC stays a true arc. A freeform spline or a flattened polyline is a chain of straight segments — how many depends on the program that wrote it and on the tolerance the laser software reads it with.

Text in DXF (TEXT, MTEXT) and dimensions need a font and are sometimes dropped or scaled wrong — convert lettering to outlines. Blocks (INSERT) are references to definitions elsewhere in the file; explode them before exporting so nothing goes missing. The most widely read variant is DXF R12 in ASCII — when the save dialog offers a version, pick that one and the laser gets plain entities every program understands.

PDF and AI — reliable size, text to check

In a PDF the unit is always the point, 1/72 of an inch — the format standard says so. That’s why a PDF from Illustrator, CorelDRAW, Affinity or a print shop loads at the right size, no guessing. The file carries curves, images and text together with embedded fonts — but LightBurn doesn’t read embedded fonts: for lettering to come in as shapes, convert it to outlines before saving or install the same font. PDFs usually have no layers but keep colors, so splitting into operations works as in SVG. Send a single page: a multi-page PDF is an invitation to import the wrong one.

A modern AI file is a PDF inside — provided Illustrator saved it with “Create PDF Compatible File” checked. Without it, other programs see only a page saying the file was saved without PDF content. LightBurn imports AI; xTool Creative Space and xTool Studio don’t (Studio does read PDF). If you design in Illustrator, save AI with that option or export PDF — both sidestep the 72/96 DPI problem that breaks SVG.

PLT and images

PLT / HPGL is the language of old pen plotters: straight segments only, in a unit of 0.025 mm (1/1016″), with a pen number instead of a color. Arcs are already broken into segments; text and images don’t exist. LightBurn imports it, xTool doesn’t. It only makes sense when an old program can’t save anything else.

PNG, JPG, BMP are images — a laser can only engrave them. The size comes from the saved DPI, and if there is none, the program assumes its own. To cut an outline you have to vectorize it — see our post on vectorizing an image for laser cutting.

.lbrn2 — a project, not a drawing

LightBurn saves projects as .lbrn2 (the older .lbrn is human-readable but bigger). Besides shapes in millimeters, it holds layers with a mode (cut, line, fill, image), power, speed, number of passes, and the cut-order optimization settings. The documentation is explicit: opening the file (Open) loads the settings, importing loads only the graphics. If someone sends you an .lbrn2 “with the settings in it,” open it — don’t import it.

Two caveats. The settings in a project fit one specific laser, lens and batch of material — someone else’s .lbrn2 on your machine is a starting point to test on a scrap, not a recipe. And only LightBurn reads .lbrn2. xTool has its own project format (.xcs); Trotec, Epilog and Universal have their own drivers. For exchanging files between shops, SVG remains the better choice.

What LightBurn imports, and what xTool does

According to both vendors’ documentation (as of October 2026; check the import dialog in your version):

The practical takeaway: everyone opens SVG and DXF; PDF works in LightBurn and xTool Studio; AI and PLT only in LightBurn. If you don’t know what the other side cuts with, send SVG.

What to send a laser shop, what to accept from a customer

If you make your cut files in the Laser MTS generators — boxes, keychains, puzzles, maps — each of them saves three files at once: SVG, DXF and a LightBurn .lbrn2 project with the layers set up, so the format takes care of itself. Customer files go through Auto-Preflight (Pro plan): it shows the detected units and the real size in millimeters, open contours, text, double lines, clones, hidden objects and images — and fixes what can be fixed with one button.

Which format when