What is STL?

STL dates from the late 1980s and the first commercial stereolithography printers. It stores only geometry: each triangle's three corners and a facet normal. There's no colour, no material, no texture and no unit of measurement.

Why it's still everywhere

Simplicity. Every slicer (PrusaSlicer, Bambu Studio, OrcaSlicer, Cura, Chitubox) reads STL, and a printer only needs the shape. If you're printing, STL just works.

The catches

• No units. A model meant in millimetres can import in inches or metres. Always check the size in your slicer.
• No colour. For multi-colour printing, use 3MF instead.
• Must be watertight. An STL needs to be a closed, manifold surface to slice correctly.
• Files get big. Binary STL is far smaller than ASCII STL. Prefer binary.

Our image to STL converter always produces a closed, solid STL, sized to 100 mm wide.