# STL to OBJ converter

> Convert STL files to OBJ in your browser with welded, shared vertices — smaller than ASCII STL and ready for Blender, Maya or a game engine. Free, no upload.

Source: https://freestlviewer.com/stl-to-obj/  
Updated: October 22, 2026

Convert .stl files to OBJ with shared vertices, ready for modelling and rendering tools. Converted in your browser — the file is never uploaded. The tool is interactive: open https://freestlviewer.com/stl-to-obj/ and drop a file onto the page.

## Why convert STL to OBJ

STL is a printing format: a flat list of triangles where every corner is
written again for every triangle that touches it. OBJ is a modelling and
interchange format with a proper vertex list. Game engines, renderers and
older 3D tools often prefer OBJ, and a welded vertex list is the starting point
for smoothing, UV unwrapping or retopology.

## What the converter does

1. Reads the STL (binary or ASCII).
2. **Welds** identical corner positions into one shared vertex, so the OBJ
   stores each point once and faces refer to it by index.
3. Writes `v` and `f` lines in millimetres — or scaled from the unit you
   choose, if the STL was exported in inches, centimetres or metres.

The geometry is unchanged: the same triangles, in the same place.

## STL vs OBJ at a glance

| | STL | OBJ |
| --- | --- | --- |
| Vertex sharing | No — corners repeated | Yes — indexed |
| Polygons | Triangles only | Triangles, quads, n-gons |
| Materials and UVs | No | Yes (via .mtl, not written here) |
| Typical use | 3D printing | Modelling, rendering, games |

## A note on smoothing

STL meshes from CAD are faceted on purpose. After importing the OBJ into a
modelling tool, use flat shading for hard-edged parts, or "shade smooth by
angle" for organic ones — the welded vertices make that possible.

## On a phone

STL to OBJ conversion works in a phone browser. The Mes3D app for iPhone, iPad,
Mac and Android exports OBJ, STL or 3MF directly after resizing or cutting a
model.

## Frequently asked questions

### How do I convert STL to OBJ?

Drop the .stl onto this page, select OBJ and click Convert and download. Identical corners are welded into shared vertices and the OBJ is written in millimetres.

### Is OBJ smaller than STL?

Usually smaller than ASCII STL and often comparable to binary STL. STL repeats every corner for every triangle; OBJ stores each vertex once and refers to it by index.

### Will the OBJ have colours or textures?

No. STL has no colour to begin with, and the converter writes geometry only. Add materials in your modelling tool.

### Do I need to convert? Blender opens STL.

Blender and most 3D tools import STL directly. Converting helps with tools and pipelines that only accept OBJ, and gives you a welded mesh with shared vertices.