GUIDES

STL vs OBJ: Which Should You Upload?

May 28, 2026·1 min read·The KTIZO team

If you're sending a model to a print shop, you'll almost always export an STL or an OBJ. Here's what actually differs and which to pick.

STL — the printing standard

STL stores geometry as a mesh of triangles. That's it: no color, no material, no units baked in (most tools assume millimeters). It's universal, every slicer reads it, and for a single-color print it's all you need.

✅ Universally supported
✅ Smallest mental overhead
❌ No color/texture
❌ Triangle-only (curves become facets at low resolution)

OBJ — when you need more

OBJ also stores a mesh, but it can carry UV coordinates and material/color data (via a companion .mtl file). For multi-color or textured models it preserves information STL throws away.

✅ Supports color/material data
✅ Can store higher-fidelity surfaces
❌ Slightly larger and less universal

Which one should you upload?

| Your situation | Upload | | --- | --- | | Single-color functional part | STL | | Multi-color / textured model | OBJ | | "I'm not sure" | STL |

For pricing, it doesn't matter: a good quote engine measures the volume and bounding box of the mesh, which both formats provide. KTIZO accepts both .stl and .obj, analyzes the geometry, and prices it the same way.

Export tips

Export in millimeters and double-check the scale before uploading.
Use a reasonable resolution — ultra-high triangle counts make huge files without improving a print you can't see at that fidelity.
Make sure the mesh is watertight (no holes); non-manifold geometry is the most common cause of a failed slice.