Simplify STL
Reduce a mesh's triangle count while keeping its overall shape, boundary loops and shell structure intact — deterministic edge-collapse simplification, verified against the actual generated output.
Your STL stays on this device. MeshWrench simplifies it locally in your browser.
Binary or ASCII STL, up to 150 MB. This limit protects your browser from freezing — it isn't a Pro restriction.
Processed locally — nothing was uploaded.
Optimization plan
- Requested reduction
- Achieved reduction
- Original triangles
- Optimized triangles
- Original file size
- Optimized file size
- Actual bytes saved
- Stop reason
Sampled geometric deviation
- Max deviation (model units)
- Mean deviation (model units)
- RMS deviation (model units)
- Samples
Deviation measurement was cut short by a safety limit — these values reflect a partial sample, not the full surface.
Surface area & volume
- Surface area before
- Surface area after
- Surface area change
- Volume before
- Volume after
- Volume change
Unresolved problems
None — every safety invariant held.
Optimizing many files? Batch optimization is planned for Pro.
Before / after
| Measure | Before | After |
|---|---|---|
| Watertight verdict | ||
| Triangles | ||
| Unique vertices | ||
| Shells | ||
| Boundary edges | ||
| Non-manifold edges |
Batch processing is a Pro capability.
Pro batch tools are being prepared. Purchasing is not available yet.
Drag files here, or click to browse
STL files only, same limits as single-file optimization.
Manage presets
Review the plan before anything is changed
- Detected issues
- Planned operations
- Skipped operations
- Eligibility
- Warnings
Steps to simplify a mesh
- Select your STL file — MeshWrench checks it locally and shows whether it's eligible for simplification.
- Pick a quality preset (Preserve details, Balanced, or Maximum reduction) and a target reduction.
- Review the plan, run the simplification, and inspect the verified before/after comparison.
- Download the simplified STL and/or a JSON report with the full verification details.
Sharp features vs. maximum reduction
Each quality preset resolves to a different maximum normal-flip angle and sampled-deviation ceiling — the exact numeric policy behind "Preserve details," "Balanced," and "Maximum reduction." None of the three presets ever disable the underlying topology-safety checks (the manifold link condition, boundary-loop adjacency, shell-membership and degenerate/duplicate-triangle guards) — a preset only ever changes how much visual detail is traded for a smaller mesh, never whether the result stays a valid, manifold-safe mesh.
What simplification preserves by default
- Manifold topology — a watertight input stays watertight in the verified output.
- Boundary loops — an open mesh's boundary edges are never merged into the interior or turned into a new hole.
- Shell count — every separate disconnected part in the file stays present.
What this tool cannot safely do
- It never simplifies non-manifold topology by default — you're directed to STL Repair first.
- It cannot guarantee an exact requested triangle count — an unachievable target stops at the best safe reduction, reported honestly.
- It cannot guarantee printability, wall thickness, or fitness for any specific printer.
Frequently asked questions
What does "simplify" mean for a 3D mesh?
Reducing the number of triangles used to represent the same overall shape, via edge-collapse simplification — merging pairs of nearby vertices in the order that changes the surface least, measured by quadric error metrics.
Will simplifying round off my model's sharp corners?
Not under the "Preserve details" preset — its tighter normal-flip and deviation limits keep genuinely sharp features intact at the cost of a more modest reduction. "Maximum reduction" trades more detail for a smaller mesh, but never breaks the mesh's manifold topology to do it.
Can I choose exactly how simplified the result is?
Yes — pick 25/50/75% fewer triangles, or type an exact target triangle count. The resolved target (after any safety-floor clamping) is always shown before you run anything.
Does simplifying preserve multiple separate parts in one file?
Yes. Shell count is preserved by default — this tool never merges or deletes an entire disconnected shell, even a very small one, as a side effect of simplifying the others.
Is my mesh uploaded anywhere to simplify it?
No. The entire simplification pipeline — analysis, the collapse loop, serialization and verification — runs locally in a Web Worker in your browser.