STL Triangle Reducer
Bring an STL file's triangle count down to a specific target — useful when a slicer or downstream tool enforces a facet-count ceiling — with manifold topology, boundary loops and shell structure all preserved and verified.
Your STL stays on this device. MeshWrench reduces 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 reduce triangle count to a target
- Select your STL file — MeshWrench checks it locally and shows its current triangle count.
- Choose "Custom target triangle count" and enter your slicer's own limit (or a percentage preset).
- Review the plan — the resolved (safety-clamped) target is shown before you run anything.
- Run the reduction, verify the achieved count in the comparison table, then download the result.
Common triangle-count / facet-count slicer errors
- "Too many facets" / "Mesh too complex": the exact case this tool targets — set an explicit target triangle count below your slicer's own ceiling.
- Slow slicing or high memory use: triangle count drives both; a moderate reduction (the "Balanced" preset) often helps without visible quality loss.
- Large file upload limits (for a cloud slicing service): binary STL size scales directly with triangle count, so reducing one reduces the other by the same proportion.
What "achieved" vs. "requested" means here
This tool always distinguishes the reduction you asked for from the reduction it actually, safely achieved. An exact target is never forced through an unsafe collapse — if your requested count isn't safely reachable (because of a shell-minimum floor or the remaining candidates all failing a safety check), the tool stops at the best safe result and reports that honestly, rather than claiming a false success.
Limitations
- Non-manifold input is never reduced by default — fix it in STL Repair first.
- An extremely small requested target relative to shell count/complexity may not be reachable — the tool explains why.
- This tool doesn't guarantee printability or fitness for any specific printer, only mesh triangle count and verified topology safety.
Frequently asked questions
My slicer says my STL has too many triangles / facets — will this fix that?
Yes — that's exactly this tool's job. Reduce the triangle count below whatever ceiling your slicer or downstream tool enforces, using an explicit target triangle count if you know the exact limit.
Can I set an exact target triangle count instead of a percentage?
Yes — switch to "Custom target triangle count" and enter the exact number. The tool clamps it to a safe minimum if needed (it will never delete an entire shell or force unsafe topology) and shows you the resolved target before running.
Why does my slicer care about triangle count at all?
Slicing performance and memory use scale with triangle count, and some slicers/printers enforce a hard ceiling. A binary STL's own file size scales directly with triangle count too — reducing one reduces both.
Will reducing triangles break my model for slicing?
No — this tool always preserves manifold topology (a watertight input stays watertight), boundary loops, and shell count, and verifies the actual output by re-parsing and re-diagnosing it before reporting success.
Is there a limit on how many triangles this tool can handle?
Yes, a disclosed safety ceiling protects your browser from freezing on an extremely dense file — this isn't a Pro restriction, and hitting it is reported honestly rather than silently producing an incomplete result.