Tiny Online Tools
Fewer triangles, same shape
A photogrammetry scan lands at 4 million triangles. A CAD tessellation at maximum quality comes back at 900 thousand. Neither will load on a phone. This free online 3D model simplifier decimates a mesh down to a budget you set, and does it in your browser with no upload.
The algorithm is quadric error edge collapse — the same approach used by professional decimation tools. Instead of naively dropping every other vertex, it repeatedly collapses the edge whose removal changes the surface least, so detail is spent where the shape actually curves and saved on flat regions. A flat wall costs almost nothing; a sculpted face keeps its features.
The two controls
Target ratio is what fraction of the triangles you want to keep. 50% halves the mesh; 5% is drastic.
Error threshold is a hard limit on how far the surface is allowed to move, relative to the model's overall size. This is the control most tools hide, and it is why the achieved ratio sometimes differs from the one you asked for: the simplifier stops early rather than exceed the error you allowed. On a dense scan you will often get below your target. On an already-optimised game asset you may not reach it at all — there is simply nothing left to remove without visible damage.
The results panel always reports the achieved count, not the requested one.
Welding matters more than you would think
An STL file is unindexed triangle soup: every triangle carries its own three vertices, and neighbouring triangles do not know they are neighbours. Decimation needs shared vertices to collapse edges across, so without welding first, simplification does nothing at all. That is why welding is on by default. Turn it off only if you know your mesh is already properly indexed.
Locking borders
On a terrain tile, a building section or any mesh that must line up seamlessly with a neighbour, moving the boundary vertices creates visible cracks. Lock borders pins them in place. On a closed object it is counterproductive — there are no borders to protect, and the option only constrains the solver.
Typical targets
- Web / product configurator — 20k–80k triangles
- Mobile AR — 10k–50k triangles
- Game background prop — 500–5,000 triangles
- 3D printing — usually no reduction needed; slicers handle dense meshes fine
How to use it
- Add your model. The source triangle count and an estimated target appear immediately.
- Drag the ratio slider until the estimate matches your budget.
- Leave the error threshold at its default unless you see damage; raise it to allow more aggressive reduction.
- Simplify, then compare the two wireframe viewports to check the silhouette held up.
- Download as GLB, STL, OBJ or PLY.
Privacy
Decimation runs in WebAssembly on your own machine. Scans, client models and unreleased assets are never uploaded.