Convert F3D to STL
An .f3d is a Fusion 360 design, and Fusion writes STL in about ten seconds. The quickest route is not in the File menu at all — it is a right-click on the body in the browser tree — and the one setting worth changing is the refinement.
We cannot read .f3d files. The format is Autodesk’s and closed, so no browser tool opens one. The export has to happen in Fusion 360, which is free for personal use; once you have the STL, or better a STEP file, everything after that runs here.
Exporting an STL from Fusion 360
Written for current Fusion releases, where the command is called Save As Mesh. In older versions the same entry was called Save As STL and the dialog was nearly identical.
Open the design
File → Open → Open from my computer… (for an .f3d somebody sent you)
A design of your own is already in the Data Panel. An .f3d file from somebody else has to be opened from your computer, and Fusion uploads it into your own cloud workspace before showing it.
Right-click what you want to print
Browser → right-click the body or component → Save As Mesh
Right-click a single body to export just that body. Right-click the top-level component — the first line of the browser tree, carrying the design’s name — to export everything visible in the design.
This is the step people miss. File, Export also writes STL, but it always takes the whole design and gives you no say over which body. The right-click is the one to learn.
Choose the format and the unit
Format: STL (Binary) · Unit Type: Millimeter
Binary, because it is about five times smaller than ASCII and every slicer reads it. Millimetres, because that is what slicers assume and an STL has nowhere to record a unit. The same dialog offers 3MF, which does record it.
Decide between one file and several
Structure: One File or One File Per Body
One File Per Body is what you want for a design with several printed parts. One File merges them into a single mesh in their assembled positions, which is right for a display model and wrong for anything meant to come apart.
Set the refinement
Refinement: High (or Custom → Surface Deviation · Normal Deviation)
Low, Medium and High are presets. Medium shows visible flats on curved surfaces at printed size; High is the sensible default for printing. Custom opens the numbers behind the presets.
In Custom, surface deviation is the furthest a triangle may sit from the true surface, and normal deviation is the largest angle between neighbouring triangles. About 0.01 mm and 5 to 10 degrees suits a part up to 100 mm. Leave Maximum Edge Length and Aspect Ratio alone unless something downstream demands them.
Save it to your computer
OK → choose a folder → Save
Leave Send to 3D Print Utility unticked unless you want Fusion to hand the mesh straight to a slicer instead of writing a file. Tick Preview Mesh first if you want to see the triangle count: a count in the millions means the refinement is tighter than a printer can use.
Check the file before you slice it
(in the STL checker on this site)
Drop the STL in and read the measured width, depth and height against the design. It takes a few seconds and it is the only place a unit mistake shows up before the print does.
What the refinement settings do to a printed part
Fusion holds a hole as a real cylinder: an axis and a radius. An STL can only hold flat triangles, so the export replaces every curve with a run of small flats, and the refinement setting decides how small.
Too coarse, and a round boss prints as a visible polygon. You can count the sides on the finished part, and press-fit holes come out slightly undersized because the flats cut across the inside of the true circle.
Too fine, and nothing gets better. A 0.4 mm nozzle cannot reproduce a deviation of a thousandth of a millimetre, so the extra triangles only make the file larger and the slicer slower. A part that exports as a 200 MB STL is a part exported at a tolerance no printer has.
High is right for most printed parts. Reach for Custom when a part mixes a large gentle curve with small tight features, because that is the case a single preset handles badly: tighten the normal deviation for the small features and let the surface deviation look after the large ones.
STL, 3MF or STEP: which one to export
STL is the answer when the next thing that happens to the file is slicing. It is the format every slicer has read for thirty years, and it carries nothing but the shape.
3MF is the better answer for the same job, where your slicer takes it — and Cura, PrusaSlicer, OrcaSlicer and Bambu Studio all do. It records the unit, so a part can never arrive 25.4 times too small, and it keeps several bodies as separate objects in one file. The Save As Mesh dialog writes it from the same Format list.
STEP is the answer for everything that is not printing. If the file is going to another person, to a machine shop, or into another CAD program, send STEP: it keeps the exact surfaces, and anybody can turn it into an STL at whatever resolution they need. The reverse is not possible. There is a separate guide here for the Fusion STEP export.
If you have an .f3d and no Fusion
An .f3d is an archive of a Fusion design — the timeline, the sketches, the bodies — in a format only Fusion reads. There is no converter for it, here or anywhere, that is not Fusion running somewhere.
The practical route is Fusion itself. Autodesk offers it free for personal, non-commercial use, and that licence opens an .f3d and exports STL, 3MF and STEP. Install it, open the file from your computer, and follow the steps above.
If installing a CAD program to convert one file is more than the job deserves, ask whoever sent it for a STEP file instead. It is File, Export for them, it takes fifteen seconds, and a STEP file converts to STL on this site with a mesh density setting of your choosing.
Autodesk’s free online viewer will display an .f3d in a browser, which is useful for checking what you were sent. It shows and measures; it does not export a mesh.
Where we can actually help
Everything after the export runs here in your browser: a STEP file from Fusion converts to STL at the density you choose, and an STL converts to 3MF so the units travel with it.
Questions
- Where is the STL export in Fusion 360?
- Right-click the body or component in the browser tree and choose Save As Mesh, then set Format to STL (Binary). File, Export also offers STL, but it exports the whole design with no choice of body.
- Can I convert an F3D file to STL online?
- Not in a browser. The .f3d format is closed and only Fusion 360 reads it. Fusion is free for personal use and exports STL directly; otherwise ask the sender for a STEP file, which does convert online.
- Which refinement should I use for 3D printing?
- High for most parts. Use Custom with a surface deviation around 0.01 mm and a normal deviation of 5 to 10 degrees when a part has both large curves and small tight features.
- How do I export several bodies as separate STL files?
- Right-click the top-level component, choose Save As Mesh, and set Structure to One File Per Body. Fusion writes one STL for each visible body.
- Is the free version of Fusion 360 able to export STL?
- Yes. The personal-use licence exports STL, 3MF and STEP. It limits other things, such as the number of editable documents, but not these exports.
Where to go next
Related guides
Tools that do part of this here
About these formats
Checked against current software versions on 2026-10-09