Convert STEP
to STL.

Updated 2026-10-07

To convert STEP to STL, drop the .step or .stp file into the converter below and download the .stl. The exact surfaces are triangulated to within 0.02 mm, with edges sampled first so holes and chamfers stay crisp, and the file is written in millimetres. 5 conversions a day are free with no account. If you are printing, PrusaSlicer, Bambu Studio and OrcaSlicer also open a STEP directly.

5 conversions a day with no account. No card, no install. In your browser: no daily limit, and the file is never uploaded.

No account needed
Drop a STEP file.step / .stp · up to 200 MB

On our servers. No account: deleted within 24 hours. Signed in: kept until you delete them. Never shared or used for training.

ResultTessellated

Edges are sampled first, so chamfers, fillets and holes come through crisp. Default tolerance: 0.02 mm chord deviation, 0.1 rad angle — fine enough to print directly.

Tessellation is one-way — keep the STEP file if you will edit the shape later.

ChangesSTEP → STL

What changes between STEP and STL

STEP stores exact geometry: a cylinder is a cylinder with a radius. STL stores flat triangles only. So every curved face becomes a fan of facets, while flat faces stay flat. The approximation here is tight: no facet strays more than 0.02 mm from the true surface, and neighbouring facets on a curve turn by no more than about 6 degrees. That is finer than a desktop printer resolves, without bloating the file.

Everything that is not shape is dropped: units, colours, assembly structure, product names. The STL is written in millimetres, so choose millimetres if your slicer asks. Several bodies arrive together in the one file.

The step is one-way. An STL is the right file to print and the wrong one to edit, because CAD software sees triangles rather than faces. Keep the STEP for any change to the design, and for anyone who will machine it.

HowThree steps
  1. Drop your .step file above — up to 200 MB without an account.
  2. STL is already selected as the output.
  3. Download the .stl. Without an account, files are deleted within 24 hours; signed in, they are kept until you delete them.
FormatsWhat you are holding

STEP file (ISO 10303) (.step / .stp)

STEP (ISO 10303) is the closest thing engineering has to a universal solid format. It stores exact B-rep geometry — a hole is a cylindrical face, not a ring of facets. Fusion 360, Inventor, Onshape, SOLIDWORKS, Creo, NX, CATIA and FreeCAD all read it; .step and .stp are the same format. AP242 supersedes AP203 and AP214.

What you send when the other side has to keep modelling, quote machining, or open the shape in a different CAD system.

STL file (stereolithography) (.stl)

STL is the lingua franca of 3D printing: a flat list of triangles. No unit, colour, material or history — a cylinder is a fan of flat strips. The missing unit is the classic cause of scale accidents. Every slicer and mesh tool reads it.

You are printing, meshing or sending to a bureau — where triangles are what is wanted.

Questions10 answered
How do I convert STP to STL?
Drop the .stp on this page, where STL is already selected, and download the .stl. .stp and .step are the same format.
Do I need to convert at all if my slicer reads STEP?
Often not: PrusaSlicer, Bambu Studio and OrcaSlicer triangulate a STEP themselves. Convert when a print service, an older slicer or a mesh tool asks for STL.
Is STL or 3MF better for printing?
3MF when the slicer takes it, because it records units and keeps objects apart. STL when someone asks for STL.
Can I get the STEP back from the STL later?
Only approximately. Converting back recovers planes, cylinders and other simple surfaces, but the original file is always more accurate, so keep it.
Is the STEP to STL converter free?
Yes. 5 conversions a day with no account and no card. A free account raises the limit and adds 25 credits. Choose In your browser instead and there is no daily limit at all.
How accurate is the STL mesh?
The exact surfaces are triangulated into a STL mesh. Edges are sampled first, so chamfers, fillets and holes come through crisp. Default tolerance: 0.02 mm chord deviation, 0.1 rad angle — fine enough to print directly. Tessellation is one-way — keep the STEP file if you will edit the shape later.
Will the STL file be the right size?
It is written in millimetres. STL records no unit, so choose millimetres if your slicer asks. 3MF records units in the file.
How big a file can I convert?
To a mesh format like STL: 300 MB with a free account, 200 MB without one. To STEP, Parasolid or SLDPRT: 140 MB, because rebuilding a solid takes about twice the memory of writing a mesh. Maker and Studio convert up to 830 MB and 380 MB — a large conversion on a paid plan gets the server to itself.
Is it safe to upload my STEP file?
Files travel encrypted and are processed by machine on our own servers — no third parties, no ads or trackers, no AI training. Or skip the upload: choose In your browser above the drop zone and this conversion runs on your own device, so the file never leaves it.
Is my STEP file deleted after converting?
Without an account, the upload and the result are deleted within 24 hours. With an account, both stay in your files until you delete them; deleted files leave our servers within 24 hours.
Beyond convertingSame file, four workspaces

Keep the part open: fill it with a lattice, check it with FEA, texture a surface, or slice it into cut-ready sheets. These workspaces are in early access — create an account, then apply from inside the app.

Create free account See pricing

AlsoOther ways in
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Going the other way? Convert STL to STEP.