OBJ to STL Converter — Convert Locally in Your Browser

Who this is for: For anyone holding a OBJ file that needs to become STL: a slicer waiting for STL. Materials (.mtl) and UVs are dropped — the .obj's geometry becomes a plain triangle mesh. If the OBJ has n-gon faces, they are triangulated.

Convert OBJ to STL in your browser — drop the file, the mesh loads instantly, download the STL. Nothing uploaded, free and unlimited.

Quick answer: The free OBJ to STL converter loads your file in the browser, renders the mesh in 3D so you can check it, and exports a clean STL — no upload, no account, no limits. Materials (.mtl) and UVs are dropped — the .obj's geometry becomes a plain triangle mesh. If the OBJ has n-gon faces, they are triangulated.

Drop a OBJ file hereor click to choose · up to 30MB

Core facts

Input	OBJ file up to 30MB — Mesh with optional material file (.mtl) and texture references
Output	STL — Triangle mesh only (vertices + face normals)
What carries over	Geometry (all triangles), exactly as loaded
What does not	Materials (.mtl) and UVs are dropped: the .obj's geometry becomes a plain triangle mesh. If the OBJ has n-gon faces, they are triangulated.
Cost	Free and unlimited — runs in your browser
Privacy	Nothing uploaded — the file never leaves your device

OBJ to STL, and what changes in the swap

Wavefront OBJ (OBJ) stores: mesh with optional material file (.mtl) and texture references. Stereolithography (STL) stores: triangle mesh only (vertices + face normals). Everything both formats share travels over completely when you convert here — the mesh — and the preview shows exactly what arrives on the other side before you commit to a download.

Materials (.mtl) and UVs are dropped — the .obj's geometry becomes a plain triangle mesh. If the OBJ has n-gon faces, they are triangulated.

This conversion runs entirely in your browser using the same WebGL engine that renders the preview: load the OBJ, inspect it from every angle, export the STL. Because nothing is uploaded and no server computes the conversion, there is no size-based price, no queue, and no daily limit — converters on this site are free without asterisks. The only practical ceiling is your own device's memory (files up to 30MB load comfortably).

Common uses

A OBJ download from a model site headed to your slicer
Pre-print inspection: check size and triangle count before slicing
Rescuing an old OBJ export whose original tool is gone
Batch-prep for printing one OBJ at a time

Frequently Asked Questions

How do I convert OBJ to STL?

Drop your OBJ file into the converter on this page — it loads and converts entirely in your browser, then you download the STL. No upload, no account, no queue. Files up to 30MB work; bigger files depend on your device's memory.

Is STL smaller or bigger than OBJ?

STL stores the same triangle mesh without textures, so for a textured GLB the STL is usually much smaller; for an OBJ or PLY, sizes end up comparable. Binary STL costs 50 bytes per triangle.

Do I lose color or textures?

In this direction: yes — STL cannot store them, by design. You keep the shape (all triangles).

Are my files uploaded?

No. The converter runs entirely in your browser using WebGL technology — your file never leaves your device. That is also why it is free with no limits: there is no server cost per conversion.

Will the scale (units) change?

OBJ has none (numbers only); STL has none (numbers only — slicers assume mm). No conversion tool can invent units that were not stored — check the part's size in your slicer and set scale there if needed.

What happens to my .mtl materials?

They are left behind — STL has no material concept. The geometry converts fully. If your OBJ uses n-gon faces (quads, etc.), they are triangulated during export, which is exactly what slicers want anyway.

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