OBJ to STL Converter
Turn any OBJ model into a print-ready binary STL, right in your browser. No uploads, no signup, no watermark.
Why convert OBJ to STL?
OBJ is a modeling format: it can carry materials, UV maps and vertex colors alongside the geometry. Slicers don't need any of that — Bambu Studio, PrusaSlicer, OrcaSlicer and Cura all want plain triangle geometry, which is exactly what STL stores. Converting OBJ to STL strips the extras and gives your slicer the simplest possible input. Fewer data channels also means fewer surprises: no missing-texture warnings, no material slots to clean up, just a mesh that slices.
That makes this conversion the standard last step when a model comes out of Blender, ZBrush, Fusion 360 or a 3D scanner as OBJ: check the mesh here in the 3D preview, then download the STL and send it straight to the printer.
The typical workflow looks like this: you sculpt in Blender or ZBrush, model in Maya, or design a part in Fusion 360, and export OBJ because it preserves materials and UV layout while you iterate. Once the shape is final and appearance no longer matters, one OBJ to STL conversion produces the file your printer actually consumes. Scanned models follow the same path — photogrammetry apps and handheld scanners usually output textured OBJ, but the printer only needs the mesh underneath.
One honest caveat: if your goal is sharing or rendering rather than printing, STL is the wrong target. It discards everything that makes an OBJ pretty — no color, no textures, no smoothing groups. For a portfolio piece or an AR preview, convert to GLB instead. But the moment a slicer enters the picture, STL's simplicity becomes the feature: every slicer on earth reads it, and nothing in the file can confuse it.
How to convert OBJ to STL
Drop your .obj file onto the converter above. It is read locally — nothing is uploaded — and rendered in the 3D preview so you can orbit around the model and confirm it loaded correctly.
Click "Convert & download" and you get a binary STL, the compact flavor every slicer accepts. Keep in mind STL is unitless: if your OBJ was modeled in meters, set the import units in your slicer accordingly.
The download is always binary STL, which stores each triangle in 50 bytes — roughly five times smaller than the ASCII variant of the same mesh, and faster for slicers to parse. The geometry is identical either way; it is purely an encoding choice, and binary is what every modern tool prefers. One practical note: STL has no unit field, so a part modeled in meters arrives in a millimeter-expecting slicer as a tiny speck — check the scale before you print, not after.
If your OBJ references an .mtl material file and texture images, don't worry about gathering them — the converter reads geometry only and ignores the material sidecar entirely. That also means a stripped-down OBJ with just vertices and faces converts perfectly. One more time-saver: the 3D preview here matches what the slicer will see, so if the model looks right on this page, it will slice right too.
Common OBJ to STL problems and how to fix them
Wrong scale is the number-one complaint, and it is never the converter's fault. OBJ exporters variously assume meters, centimeters or plain unitless numbers, while slicers almost universally expect millimeters. A model that shows up a thousand times too small is a classic meters-to-millimeters mix-up. The fix takes seconds: scale the imported STL by 1000% (meters to mm) or 10x (centimeters to mm) in Bambu Studio, PrusaSlicer or Cura — or re-export the OBJ in millimeters so every future conversion lands correctly.
Second classic: 'my textures disappeared.' That is expected behavior, not a bug — STL physically cannot store color or UV data, so every OBJ to STL conversion drops them by design. If you were converting for a full-color print, switch targets: export 3MF from your slicer or convert the OBJ to GLB, both of which carry materials. For single-filament FDM or resin printing the loss is irrelevant, because the printer never sees color anyway.
Third: slicer warnings about holes, reversed normals or non-manifold edges. The converter preserves your geometry faithfully — including its defects. Game assets and downloaded models frequently have open edges, internal walls or intersecting shells that render fine on screen but slice badly. Run the mesh through Blender's 3D Print Toolbox or Meshmixer's analysis before converting, and fix issues at the source. A watertight OBJ converts to a watertight STL, every time.
OBJ to STL FAQ
Does converting OBJ to STL lose quality?
The geometry is preserved triangle-for-triangle — vertices and faces come through unchanged, so dimensions and detail are identical. What you lose is everything STL cannot store: materials, UVs, vertex colors and smoothing groups. For 3D printing none of that matters, since slicers ignore appearance data anyway and only read the triangle soup. If curved surfaces look faceted after conversion, they were faceted in the OBJ too — the conversion adds no new artifacts.
Will my OBJ textures carry over to the STL?
No — the STL format has no concept of textures or color at all, so nothing in the conversion can keep them. If the materials matter, convert to GLB instead of STL: GLB packs geometry, UVs and textures into a single modern file that viewers, game engines and AR tools all read. For a full-color 3D print, export 3MF. Choose STL when the model is headed to a single-color printer, which is most printing.
Is there a file size limit?
Files up to 50 MB convert comfortably in the browser, because the whole job runs in your device's memory — no server round-trip. Larger meshes can hit browser memory limits on some devices, especially phones. If yours is bigger, decimate the model in Blender or Meshmixer first; most models print identically at a fraction of their original polygon count, since FDM printers can't reproduce sub-nozzle detail anyway.
Is the output STL ready for my slicer?
Yes. The converter exports binary STL with proper facet normals — the flavor accepted by Bambu Studio, PrusaSlicer, OrcaSlicer, Cura and every other mainstream slicer. Two things to verify on import: scale (STL does not record units, so confirm the dimensions look sane in millimeters) and orientation (Z-up vs Y-up conventions differ between modeling tools). Both are one-click fixes in the slicer if they're off.
What is the difference between binary and ASCII STL?
Both describe the same triangles. ASCII STL is human-readable text — you can open it in an editor and see the vertex coordinates — but it is four to six times larger and slower to load. Binary STL packs the same data compactly and is what slicers handle best. This converter outputs binary STL, which is the safe default; you would only want ASCII for debugging or editing coordinates by hand.
Why does my STL look tiny (or huge) in the slicer?
STL files don't record units, so the slicer assumes millimeters. If your OBJ was modeled in meters (Blender's default), the numbers import 1000x too small; if it was modeled in inches, about 25x off. Scale the model in the slicer — 1000% for meters, 2540% for inches — or re-export from your modeling software in millimeters and convert again. The geometry itself is never damaged, just mislabeled.
Can I convert a textured OBJ for full-color 3D printing?
Not with STL — the format has no color channels at all, so any OBJ to STL conversion drops textures by design. For full-color printing (for example a Bambu Lab printer with AMS, or an MJF print service), export 3MF from your slicer or convert the OBJ to GLB; both carry color and material data. Plain STL is the right choice whenever the print will be a single filament or resin color anyway.