What is inside an .ipt, and why nothing free reads it
An Inventor part stores its geometry in Autodesk’s ShapeManager kernel format — a fork of ACIS — wrapped in a compound document with the parametric feature tree, iProperties and drawing references. Autodesk publishes no specification; the reader lives inside Inventor, Fusion 360, Navisworks and the Autodesk Platform Services translation API. A website advertising in-browser IPT conversion is therefore reading, at most, the thumbnail or the tessellated “dumb” preview some files embed — not your model. Sites that do convert it properly are uploading it to a cloud running Autodesk’s licensed translator.
CADverter takes the neutral route and says so: it reads STEP, IGES and BREP, plus every common mesh and drawing format, and cannot open .ipt or .iam. Inventor exports STEP in a few clicks, described next.
Exporting STEP from Inventor, step by step
- 1
Open the part (.ipt) or assembly (.iam).
- 2
Choose File → Export → CAD Format. (Older releases: File → Save Copy As; the dialog is the same.)
- 3
Set Save as type to STEP Files (*.stp, *.ste, *.step).
- 4
Click Options. Choose the Application Protocol — 214 — Automotive Design is the default and the right choice for most tools; 203 for very old receivers; 242 when the recipient wants PMI or asks for it. Leave Include Sketches off unless needed. Keep the Spline fit accuracy at its default — it only affects how free-form surfaces are approximated, and the default is tight.
- 5
Under Export choose Solids (or Solids and Surfaces if the part has open surface bodies you need). Click OK, name the file, Save.
Drop the resulting .stp on this page. It opens in 3D with its assembly tree, and Convert offers STL, 3MF, OBJ, PLY, GLB, USDZ and the rest, or Make drawing produces a dimensioned DXF, SVG or PDF sheet.
Exporting an assembly (.iam)
The same command from an assembly document writes a single STEP containing every component with its placement and the occurrence tree. Suppressed components are omitted; components in a Level of Detail representation follow that representation, so switch to the master LOD first if you want everything. CADverter shows the tree in its parts panel; Ctrl+click components to include or exclude them from a conversion, or write one file per part into a ZIP.
Units are carried — check them once
STEP declares its length unit and Inventor writes the document unit, so a part modelled in inches arrives here as inches and is shown correctly; conversions to STL are written in millimetres and the panel says so, since STL cannot carry a unit. Look at the bounding-box size in the viewer after the drop: if a 4-inch part reads 101.6 mm, everything is right.
Inventor exports STL directly — when to use that instead
Honest counter-advice: File → Export → CAD Format also offers STL, with a resolution dialog and a choice of units. If STL is the only thing you need and you are sitting at Inventor, that is one step fewer. Export STEP and convert here when you also need 3MF with parts kept separate, GLB or USDZ for the web and AR, OBJ with colours, a 2D drawing sheet, or when the person who needs the file has no Inventor — they drop the STEP here and take whatever their tool reads.
Which application protocol to choose
AP203 carries geometry and assembly structure; AP214 adds colour, layers and validation properties and is the everyday default; AP242 is the current standard and adds product manufacturing information. For any conversion on this page the three produce identical geometry, so AP214 is the safe pick unless someone downstream specifies. Colours exported under AP214 or AP242 show in CADverter’s viewer and pass into OBJ, 3MF, GLB and its own STEP writer.
Verifying the export
Drop the file here and check three things: the parts panel shows the expected component count; the bounding box is in the unit you modelled in; and curved faces shade smoothly. A body missing from the tree was probably suppressed or in a different LOD; a part that appears as loose surfaces had an open body in Inventor — run Inspect → Analyze there and stitch before exporting. Nothing on this page is uploaded during any of this, so checking costs nothing but a drag and drop.
Inventor export questions
Can I convert an .ipt to STL without Inventor?
Not with any browser tool, honestly. Fusion 360 (which has a free personal licence) opens .ipt and exports STEP or STL; or ask the author for a STEP export. Once you have STEP, everything on this page works.
Does the STEP keep the assembly structure?
Yes, when exported from the .iam. Each component is a product with its placement; CADverter shows the tree and can write one file per part.
Which STL export is better — Inventor’s or CADverter’s?
Both mesh the same exact geometry. Use Inventor’s when you are at the seat and STL is all you need; use CADverter for other formats, for batches, or when the machine has no Inventor.
My exported STEP is huge — is that a problem?
No. There is no upload, so there is no size limit beyond your computer’s memory. Large surface models are normal for STEP.