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Good to know
If your OBJ looks wrong
- It's grey: the colours are in a .mtl file and textures that weren't loaded. The shape is still all there.
- It's lying on its back: OBJ usually treats Y as up. For printing, OBJ to STL stands it upright.
- It's tiny: the file is probably in metres. OBJ to STL lets you type the height you want.
- Bits seem missing: some faces point inward. Switch to Wireframe to see them, and run the STL repair tool if you plan to print it.
About OBJ files
OBJ is an old, plain-text 3D format that almost every app reads. Colours live in a separate .mtl file and image textures, so a lone OBJ shows grey.
OBJ files don't say what unit they use. Blender writes them in metres, so a 10 cm figure can arrive as 0.1 mm. The size shown here assumes millimetres.
How it works
- 1Drop a OBJ file in the box.
- 2Drag to spin it. Scroll or pinch to zoom. Right-drag to pan.
- 3Read the size, triangle count and whether it's watertight in the panel.
Questions people ask
Checked October 2026
- Do my files get uploaded?
- No. Everything runs in your browser. The file never leaves your computer, so it works for client files and unreleased designs too.
- Why is it grey?
- Colours in an OBJ live in a separate .mtl file and textures. We show the shape only, which is what you need to check a model.
Other tools you might need
STLPalConverter
OBJ→STL
Free · in your browser · no upload
OBJ to STLOBJ files from Blender or a game usually lie on their back and come in odd sizes
STLPalConverter
STL→OBJ
Free · in your browser · no upload
STL to OBJBring a printable STL into Blender, a game engine or a renderer as an OBJ
STLPalViewer
.STL
Free · in your browser · no upload
STL viewerOpen any STL to look it over before you print
STLPalViewer
.FBX
Free · in your browser · no upload
FBX viewerLook at an FBX without installing anything