STL vs 3MF: Which Should You Export?
When you’re ready to 3D print, your slicer will happily take an STL or a 3MF. Both describe the same triangle mesh of your part, so for many prints it genuinely doesn’t matter which you pick. But 3MF is the newer format and carries more information. Here is the plain-English difference and a simple rule for choosing.
Both are meshes for printing
First, the thing they share: both STL and 3MF store your part as a mesh — a shell of triangles that approximates the surface. That’s exactly what a 3D printer’s slicer wants. Neither is a true solid the way a STEP file is, so if you need to keep editing the geometry or send it to a CNC shop, export STEP instead — see STL vs STEP.
The short version
STL and 3MF are both for 3D printing. STEP is for CNC and editing. If you’re printing, either of these works.
The difference: how much they carry
STL — geometry only
The classic, universal format. It stores just the triangle mesh — no units, no color, no metadata. Every slicer and printer on earth reads it, which is why it’s still the safe default.
3MF — geometry plus extras
A modern, compact format that can also carry units, color, and multiple objects in one file. It avoids some of STL’s old ambiguities (like missing scale) and is the preferred format in many newer slicers.
For a plain single-color print, the result is identical — same mesh, same part. 3MF starts to win when color, exact units, or several parts in one file matter.
Which to pick
- Use STL when you want maximum compatibility, or you’re sending the file to a print service that asks for it. It always works.
- Use 3MF when your slicer recommends it, or you want units and color baked in so nothing is guessed on import.
Either way you’re printing a mesh, so the usual print rules apply — especially tolerances for any holes or fits that need to come out the right size.
Export STL or 3MF in your browser
You don’t need desktop CAD to get a print-ready file. Describe your part to PartWork.ai, then export an STL or 3MF for printing — or a STEP solid if you’re going to CNC. See exporting for the available formats, and creating parts for getting the geometry right first.
Start with 2 free AI generations — no card required
Open the studio, describe your part, and export an STL or 3MF ready to slice. More credits: 100 for $4.99 (~5¢ each).