Free STL to OBJ Converter
Drop an STL file below to save it as an OBJ that modeling and rendering apps open. Your file is never uploaded.
Your files never leave your browser. Nothing is uploaded.
What are STL and OBJ files?
STL is the plain format of 3D printing. It stores a model as a list of triangles and nothing else: no colors, no textures, and no unit. Slicing programs and CAD tools all read it.
CAD apps such as Fusion and Onshape export STL, and so does Blender. Model sites such as Thingiverse and Printables list printable models as STL.
OBJ, also called Wavefront OBJ, is an old and simple text format for 3D shapes. It lists points and the faces that join them. Almost every 3D app can read and write it, which makes it a common way to move a model between programs.
Almost every 3D app reads OBJ, so it is a safe choice when a program does not accept your model's format. It carries shapes but not colors, textures, or animation.
How to convert STL to OBJ
Step 1. Drop your STL file on the converter above, or choose it from your device.
Step 2. Look at the preview. If the model lies on its side, change the up direction to match your file.
Step 3. Press the download button. The OBJ file is saved to your device, named like your original with .obj at the end.
Bringing a printable part into a modeling or render app
STL is the output of CAD and print software. Modeling and rendering apps often prefer OBJ, and some of them cannot read STL well. Converting an STL to OBJ lets you texture, rig, or render a part.
The converter turns the model from Z up to Y up, which is what most OBJ users expect, and keeps the numbers as they are, so a part 50 mm wide reads 50 in the OBJ. Set your app's import scale if it expects meters. An STL has no UV coordinates, so unwrap the model in your app before you add textures.
What survives the conversion
Shapes. Binary and text STL files are both read. Shapes are written with normals and UV coordinates.
Colors and materials. STL has no colors, so the model starts out plain. No .mtl file is written, so colors are not kept.
Textures. STL has no textures. Textures are not kept.
Animation. STL cannot hold animation. Animation is not kept, so the model is saved in its first pose.
Units and direction. STL does not say which unit it uses. Slicers read it as millimeters, so that is the starting choice here. Numbers are written as they are, with Y pointing up. OBJ has no unit.
If something looks wrong
If the model lies on its side, change the up direction to Y.
A model with holes or flipped faces was already broken when it was exported. Repair it with your slicer's repair tool before you print.
Faces that were flipped in the STL stay flipped in the OBJ. Repair the STL first if the part looks inside out.
The OBJ has no .mtl file, so most apps show it in plain gray. Add the colors again in the app you open it in.
If your browser cannot draw 3D, there is no preview, but the conversion still works.
Your file stays on your device
The converter reads your STL file in the browser and writes the OBJ file there too. Nothing is uploaded, and the page does not load anything the file points to, other than files you choose yourself. The page counts a visit like any other page, but it never sees the file's name or contents.
Questions
Is this STL to OBJ converter free, and is my file uploaded?
It is free, and you do not need an account. Your file is read and converted in your browser and never uploaded, so it stays on your device.
Does the OBJ keep the size?
Yes. The numbers are written as they are, in the unit your STL was made in, which is usually millimeters.
Why is there no .mtl file?
An STL holds no colors or pictures, so there is nothing to put in one. The converter never writes a .mtl file.
Which unit and direction does the OBJ file use?
Numbers are written as they are, with Y pointing up. OBJ has no unit.
How large a file can I convert?
Files up to 150 MB. A very large model may convert slowly on a phone or an older computer, so export only the part you need if it struggles.
More free tools
- Free OBJ to STL ConverterConvert an OBJ file to STL for 3D printing in your browser. Choose the unit and get a binary STL. Free, with no upload and no sign-up.Free, in your browser
- Free STL Viewer OnlineOpen an STL file in your browser. Turn it, zoom in, and check the triangle count and size before you print. Free, with no upload and no sign-up.Free, in your browser
- Free OBJ Viewer OnlineOpen an OBJ file in your browser. Turn it, zoom in, and check the triangle count and size. Free, with no upload and no sign-up.Free, in your browser
- Free STL to GLB ConverterConvert an STL file to GLB in your browser to share a printable part on the web or in AR. Free, with no upload and no sign-up.Free, in your browser
- Free STL to 3MF ConverterConvert an STL file to 3MF in your browser. Joins matching corners and states the unit. Free, with no upload and no sign-up.Free, in your browser
- Free GLB to OBJ ConverterConvert a GLB file to OBJ in your browser. Keeps shapes, normals, and UV coordinates. Free, with no upload and no sign-up.Free, in your browser
Make it a finished render
Open the studio and add your STL file. The studio opens GLB, glTF, OBJ, FBX, STL, 3MF, or DAE files. You pick the angle and describe the finish, and Inkfinish renders that view as a finished image.
Try 3 renders free, no sign-up needed: watermarked, at standard size.
Updated October 2026. Open-source licenses