Convert STEP to DXF
A STEP file is a 3D solid and a DXF is a flat drawing, so this makes a drawing *of* the model rather than a copy of it. Take the outline seen down one axis, or a cross-section at any height. Both come out as an R12 DXF a cutting machine will read.
Drag a 3D file here, or.
This page is set up for STEP files. Other formats we can read work here too.
The file is read on your own computer. It is never uploaded.
Your file is read by your own browser and never sent to a server. There is no upload, no account and no copy of your model anywhere but on your computer.
This is also the honest answer to "STEP to DWG"
A great many people looking for this are really looking for a DWG, because that is what their shop asked for. No free tool can write a DWG: it is AutoCAD’s own format, and writing it needs a paid membership of the Open Design Alliance.
A DXF is the format that exists for exactly this reason. It was published by Autodesk as the interchange version of DWG, every program that opens a DWG opens a DXF, and for a flat profile going to a cutting machine there is no practical difference. If somebody has asked you for a DWG, send them this and it will open.
A drawing of a solid means choosing what to throw away
An outline is the shape of the model’s shadow down one axis — the footprint, if you look down Z. This is what a backing plate, a gasket blank or a mounting pocket needs.
A cross-section is the shape of a cut through the model at a chosen height. This is what a profile, a template or a machining setup needs.
Both are offered in the box above the button and the drawing rebuilds as you switch, so you can see which of the two you actually meant before you download anything.
The detail setting decides the drawing, not just the model
A STEP file has no triangles in it. A cylinder is a radius, an axis and a height — the exact surface. How many flat strips it becomes is decided while the file is being read, by you, using the detail control.
That matters more here than it does for a 3D output, because the outline you get is the outline of the triangles rather than of the true surface. On a draft setting, a circular hole comes out as a visible polygon. For anything going to a cutting machine, use fine.
Units come across correctly
A STEP file states its unit and the CAD engine hands the numbers back in it, so the sizes beside the 3D view are facts rather than guesses. The DXF then states its own unit in its header, so the drawing arrives in your CAM software at the right size.
That is a genuinely unbroken chain from the CAD model to the cutting table, which is not something you get by going through STL in the middle — an STL records no unit at all.
What survives, and what does not
Kept in the DXF file
- The exact outline or section, at the size the STEP file declares
- Holes and internal openings, as separate closed paths
- The unit, stated in the DXF header
Lost on the way
- The third dimension — that is what makes it a drawing
- Exact curved surfaces, which become fine straight segments
- Assembly structure, part names and colours
How to convert STEP to DXF
Drop the .step or .stp file in
The CAD engine is fetched the first time you do this, once, and your browser keeps it for the next file.
Set the detail to fine
The outline follows the triangles, so a coarse setting gives a visibly polygonal hole. Fine costs a moment and gives a smooth edge.
Choose outline or cross-section, and the axis
Looking down Z gives the footprint. The height slider runs from the bottom of the model to the top.
Set the output unit and download
It is written into the DXF header. Measure one known dimension in your CAM software before cutting anything.
STEP and DXF compared
| Property | STEP.step .stp | DXF.dxf |
|---|---|---|
| File contents | Plain text in the ISO 10303-21 exchange form. Readable, and enormous. | Plain text in numbered group codes, with a binary variant nobody uses. |
| Geometry | Exact surfaces: planes, cylinders, cones, spheres, NURBS. Not triangles. | Lines, arcs, circles, polylines and splines, in 2D and limited 3D. |
| Units | Recorded in the file, as a full unit and tolerance context. | Recorded in a header variable, as one of twenty-odd unit codes. |
| Colour and texture | Colour per face or per solid, through the AP214 and AP242 styling entities. | A colour number per entity, and colour by layer. |
| Separate objects | An assembly tree of named parts, each with its own placement. | Named layers, plus blocks for repeated geometry. |
| Published by | ISO 10303, from 1994. AP242 is the current application protocol. | Autodesk, 1982, as the published counterpart to the closed DWG. |
| Written by | SolidWorks, Fusion 360, Inventor, CATIA, FreeCAD, Onshape — every serious CAD program. | AutoCAD, LibreCAD, QCAD, Fusion 360 and every laser cutter’s software. |
Questions
- I was asked for a DWG. Is this good enough?
- For a flat profile going to a cutting machine, yes. DXF is the published interchange form of DWG and every program that reads one reads the other. No free tool can write a DWG, so if the request is strict, the file has to go through AutoCAD or a paid converter.
- Why is my circular hole a polygon?
- The detail setting was too coarse. A STEP file holds the exact circle, but the drawing is taken from the triangles it was chopped into. Set the detail to fine and it comes out smooth.
- Can I get the flat pattern of a sheet metal part?
- No. Unfolding a bent part is a different operation that needs the bend information, and a STEP file does not reliably carry it. Use the flat-pattern export in the CAD program that made the part.
- Is my CAD file uploaded?
- No. The CAD engine is downloaded to your browser and the file is read there. Nothing about your model is sent anywhere, which for commercial CAD work is usually the point.
Having it cut
If you do not have a machine, these will cut this drawing from sheet material and post it to you. Upload the file you just downloaded; all three quote from it directly.
- SendCutSendLaser-cut sheet metal and plastic, no minimum order
- PonokoLaser cutting in acrylic, wood and card, single pieces
- PCBWayCNC machining and sheet metal from a drawing
These are ordinary links, not paid referrals — we earn nothing if you use them. The converter above is the same whether you do or not.