STL ⇄ OBJ 3D Model Converter Community
Questions, answers and tips from people who use the STL ⇄ OBJ 3D Model Converter. Convert STL, OBJ, PLY, 3MF, AMF, GLB — batch, with unit fix.
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From the tool guide: common questions about STL ⇄ OBJ 3D Model Converter
The items below are not posts by community members. They come from the written guide for this tool and are here to get a conversation started. Use “Ask a follow-up” to open a thread about any of them.
Can I convert many files at once?
Yes — drop several files; each is converted and you can download them individually or as a ZIP.
From the tool guide Ask a follow-upDoes it keep colours and textures?
No — only the mesh geometry is converted; STL cannot store colours and OBJ materials are not carried over.
From the tool guide Ask a follow-upCan it convert CAD STEP files?
Use the STEP to STL converter; STL to STEP is available too.
From the tool guide Ask a follow-upDoes this actually convert the file, or just rename it?
It genuinely parses the real triangle/vertex data and rebuilds the file in the target format — STL and OBJ store geometry differently, so a rename alone would not work.
From the tool guide Ask a follow-upCan I convert OBJ to STL and back without losing precision?
Coordinates are carried through as full floating-point values, so there's no meaningful precision loss from the format conversion itself.
From the tool guide Ask a follow-upWhat does the scale factor do?
It multiplies every vertex coordinate by the number you enter — use 25.4 to convert inches to millimetres, or 1/25.4 (≈0.03937) to convert millimetres to inches.
From the tool guide Ask a follow-upDoes it preserve color or texture data?
No — it preserves the mesh geometry (vertices and faces), which is what 3D printing and most CAD/slicer workflows need; OBJ material/texture references are not carried over.
From the tool guide Ask a follow-upIs my file uploaded anywhere?
No. Parsing, conversion and rendering happen entirely in your browser; the file is never sent to a server.
From the tool guide Ask a follow-upWhat this tool does
STL and OBJ are both triangle-mesh formats, but a lot of CAD, slicer, game and 3D-editing software only accepts one of them. This tool does a real conversion: it parses the triangle and vertex data from your file and rebuilds it in the target format — binary or ASCII STL, OBJ, binary or ASCII PLY, 3MF, AMF, OFF or GLB. Drop in several files at once and you get a list of results with one-click downloads and a ZIP of everything.
How to use it, step by step
- Drop in an .stl or .obj file.
- Choose the output format (binary STL, ASCII STL or OBJ).
- Optionally set a scale factor for unit conversion.
- Preview the result and click Download.
Tips from the guide
- OBJ files can reference vertex normals and texture coordinates the model doesn't need for 3D printing — this converter reads the vertex/face geometry (the part that matters for STL) and doesn't preserve textures.
- If a slicer reports a model is the wrong size by close to a factor of 25.4, the source file was very likely modeled in inches — use the scale factor to fix it in the same step as the format conversion.
- Binary STL produces a much smaller file than ASCII STL for the same mesh — prefer binary unless a specific tool requires ASCII.
Common mistakes to avoid
- Assuming format conversion alone fixes a differently-scaled model — if the original units were wrong, apply the matching scale factor during conversion rather than guessing dimensions later in a slicer.
- Expecting OBJ texture/material data to carry over — this conversion preserves the real geometry (vertices and faces), which is what matters for 3D printing, not textures or materials.
- Converting a non-manifold or otherwise broken mesh and expecting the converted file to suddenly be watertight — format conversion doesn't repair mesh geometry issues.
Who uses it
- Makers whose slicer only accepts STL. Convert an OBJ export from a 3D design tool into STL in one step.
- Anyone importing a printed model into a 3D editor. Convert STL to OBJ for tools that expect OBJ's vertex/face format.
- People fixing a model exported in the wrong units. Apply a real scale factor during conversion instead of rescaling manually in a separate program.
How to ask a question people can answer
A good thread on the STL ⇄ OBJ 3D Model Converter saves everyone time. Start with a title that names the exact problem, such as the input you used, the result you expected and the result you got. A title like “Not working” is hard to answer, while a title with the specifics gets replies quickly.
- Say what you tried. List the steps you followed and any settings you changed, so replies do not repeat what you already did.
- Share a small example. A short sample input and the output you saw is worth more than a long description. Remove anything private first.
- Mention your setup. Your device, browser and whether you are on a phone or a computer can explain many odd results.
- One question per thread. Separate topics get clearer answers and are easier to find later with the search box above.
- Come back and reply. If a suggestion worked, say so and upvote it, and if you found the fix yourself, post it for the next person.
Community rules
Be kind, stay on topic and keep personal data out of your posts. Do not post adult, hateful or illegal content, advertising or repeated links. Every post is shown with its author’s username and date, and posts that break these rules can be hidden by moderators. This space is for help with the STL ⇄ OBJ 3D Model Converter and related tasks, and it is separate from the sitewide discussion forum where broader topics live.