Reduce STL file size

1. Drop your STL, OBJ or 3MF above.
2. Pick how much to keep: 25% is a good start. The panel shows the new triangle count, the new file size and how far the surface moved, in millimetres.
3. Switch between Original and Reduced, with the triangles shown, to compare.
4. Download the smaller STL or 3MF.

Your file is processed on your device. Nothing is uploaded.

Fewer than most files have. A 0.4 mm nozzle printing 0.2 mm layers can't show details much smaller than about 0.1 mm, so a mesh only needs enough triangles to stay that close to the true shape. The panel tells you exactly that: if the shape moved by less than about 0.05 mm, the print will look the same.

Every triangle costs 50 bytes in a binary STL, so a 2-million-triangle scan is about 100 MB. Reduced to 10%, it is about 10 MB and slices much faster.

A little, where it matters least. The tool collapses short edges on flat and gently curved areas first and keeps corners and sharp details as long as possible (the quadric error method by Garland and Heckbert, as implemented in meshoptimizer). The model stays a closed, watertight solid; open edges, if your file has any, are kept where they are.

If the amber note says details may soften, keep more triangles, or reduce only the parts you don't mind: untick the parts to export in a multi-part 3MF.

• 3D scans and photogrammetry capture millions of points, far more than a printer can show.
• AI-generated models (from images or text) are often very dense.
• Sculpts from ZBrush or Blender are made at high detail for rendering.
• CAD exports at a very fine tolerance turn every curve into thousands of slivers.

Big files slice slowly, can make slicers and browsers run out of memory, and may be too large to upload to model sites. If the file also has holes or errors, repair it first; if it's too big for your printer rather than too heavy, split it.