Reduce STL
File Size
Cut the triangle count of a heavy STL or OBJ so it slices faster, loads quicker, and takes less space — without wrecking the shape. Quadric edge collapse drops triangles across flat areas first and keeps the detail where the surface curves.
Free for files up to 25 MB, no signup. Files are deleted automatically within 24 hours.
Drag & drop files here or Browse
Auto-detects CAD, Video, PDF, and 200+ formats
What You Get
Decimation trades a little geometric accuracy for a much lighter file. On an over-tessellated mesh that trade is nearly free.
Faster slicing and loading
A slicer, viewer, or game engine chews through a few thousand triangles far quicker than a few million.
Smaller files to store and send
Dense scans and sculpts run to hundreds of megabytes; most of that detail never reaches the print.
Detail kept where it counts
Quadric edge collapse merges triangles across flat areas first and holds on to high-curvature features.
Watertight stays watertight
Edge collapse preserves the manifold, so a closed solid comes back closed and still printable.
Before/after numbers
Triangle count, file size, and any volume drift are printed to the console, so the saving and any shape change are both visible.
STL and OBJ input
Upload either; you get a reduced STL back. Best on organic meshes and scans, not on already-lean CAD exports.
How It Works
Measure
The mesh is loaded and measured: triangle count, file size, bounding dimensions, and enclosed volume if it is a closed solid. These are the before numbers you will compare against.
Collapse
Quadric edge collapse merges the least-important triangle pairs first, so flat regions thin out while curved detail is preserved, down to your target percentage or triangle count.
Report
The result is measured again. The console prints how many triangles and bytes were saved, and warns if the enclosed volume drifted more than 1% — so nothing about your part changes silently.
When decimation is the wrong tool
If you still have the source CAD or a STEP file, re-exporting at a coarser resolution beats decimating — it tessellates from the exact surfaces instead of approximating an approximation. Reach for this tool when the mesh is all you have: a scan, a sculpt, a downloaded STL with no lower-poly source.
Decimation is not repair. If your file has holes or non-manifold edges, reducing it first can make those worse. Run it through the STL Checker & Repair tool first, then simplify the clean result.
And it will not un-facet a coarse mesh. Reducing triangles is one-way: it cannot add back detail that was never there or that a previous reduction removed. Keep your original if you might need the high-resolution version again.