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Reduce an STL to under 25 MB

25 MB is the most common wall an STL hits: Tinkercad imports stop there, Gmail attachments do, and Thingiverse enforced it for years. In binary STL it is about 524,000 triangles. This page opens the reducer at 24 MB so the file clears the limit with a margin for encoding and checks.

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Drop an STL file here or click to browse
Up to 300 MB · .stl only
Choose STL file
1
Upload STL
2
Set target MB
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Download
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1 MB500 MB

We aim for exactly this size. Quality-preserving quadric decimation stops as soon as the file fits. If the mesh cannot be reduced further without breaking, we return the smallest safe result.

Pick an STL file to continue.
🔒 Files are processed on our server in isolated memory and removed within 15 minutes of your download.

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The limit: 25 MB

File size cap
25 MB
Triangle cap
no fixed cap
Triangles at that size
524,286

This page opens the reducer at 24 MB. Source: Tinkercad, Gmail and Thingiverse-era limits (checked 2026-09).

Why the file is over it

Any model that started life as a scan, a sculpt or an AI generation carries one to five million triangles, ten times what 25 MB allows. CAD exports at fine tolerance can reach it too, and an ASCII STL of a model that would be 10 MB in binary is already over. The triangles above the print resolution are the ones the reducer removes.

How to get under it

  1. 1Drop the STL below. The target is preset to 24 MB.
  2. 2Press Reduce. The tool converts ASCII to binary first, repairs the mesh, then decimates only as far as needed to reach 24 MB.
  3. 3Read the result card: if the target was hit the file is under 25 MB; if the mesh could not go lower safely it says so and gives the smallest safe size.
  4. 4Download.
Reduce to under 25 MB

What to expect

A 100 MB binary STL (2.1 million triangles) to 24 MB keeps 500,000. At 0.2 mm layers on a 100 mm part, that is more triangles than layers times perimeter points; the print is identical. Texture finer than about 0.15 mm on the surface is where the difference lives, and it is below what FDM can render.

Other ways

Blender's Decimate and MeshLab's Quadric Edge Collapse reach the same result with a ratio and a few tries. Zip compression gains only 10 to 20 percent on binary STL and does not help with an import limit.

Questions

Is 25 MB the same as 25,000 KB?

Platforms usually mean 25 × 1,048,576 bytes, about 26.2 million bytes. The reducer targets the binary-megabyte definition, so a 24 MB result is under both readings.

What if the model cannot go under 25 MB without breaking?

The reducer stops at the smallest watertight result it can produce and tells you. That is rare below 300 MB inputs; splitting the model into parts is the fallback.

Does 24 MB fit Tinkercad's triangle limit too?

Not necessarily: Tinkercad also caps at 300,000 triangles, about 14 MB. Use the Tinkercad page for that target.