The limit: Tinkercad
- File size cap
- 25 MB
- Triangle cap
- 300,000
- Triangles at that size
- 524,286
This page opens the reducer at 22 MB. Source: Tinkercad import dialog (checked 2026-09).
Why the file is over it
Tinkercad's limit is really a triangle limit: 300,000 triangles is about 14 MB of binary STL, so a file can be under 25 MB and still be refused. A photogrammetry scan is typically 1 to 5 million triangles; a Blender sculpt exported at full resolution is often more. Tinkercad also converts every import to its own solid representation, which is why it keeps the cap low.
How to get under it
- 1Drop the STL below. The target is preset to 22 MB.
- 2Press Reduce. Quadric decimation removes triangles where the surface is flat first, so edges and curves keep their shape.
- 3Check the result card: it shows the triangle count after reduction. If it is still above 300,000, set the target to 12 MB and reduce again.
- 4Download and import into Tinkercad as usual.
What to expect
A 60 MB scan (about 1.25 million triangles) reduced to 12 MB keeps roughly 250,000 triangles: the silhouette and large features survive, fine surface noise goes. For a mechanical part exported from CAD the loss is usually invisible, because most of its triangles were spent on flat faces.
Other ways
Blender's Decimate modifier and MeshLab's Quadric Edge Collapse do the same job on the desktop, with a learning curve and a 3 GB install. Tinkercad itself has no simplify option. If the model is a CAD part, re-exporting from the CAD program with a coarser STL tolerance is the cleanest fix.
Questions
Is it the 25 MB or the 300,000 triangles that matters?
Both are checked, and the triangle cap bites first: 300,000 triangles is about 14 MB. Aim for under 12 to 14 MB to be safe.
Will the model still be solid in Tinkercad?
Yes, if it was watertight before. The reducer checks watertightness before and after and repairs common defects first; the result card shows both.
Can I reduce a Tinkercad export for another use?
Yes. Tinkercad exports are usually small, but a large group of shapes can exceed marketplace limits; use the same tool with the target that destination needs.