SMALLER MESHES. SAME DEVICE.

STL Compressor

Q: Is STL compression lossless?

Triangle reduction is lossy. Retaining 100% converts an ASCII STL to binary without simplifying the stored geometry.

Q: Why did the result stop above my target?

The error limit, locked boundary vertices and mesh topology may prevent further simplification. Target triangle counts are not guaranteed.

Q: Does it keep units, UVs and materials?

Coordinates are not rescaled, but simplification can change dimensions slightly. STL has no standard units, UV maps or material data. Normals are recalculated.

Q: How large can my STL be?

Up to 50 MB and 500,000 triangles, subject to device memory. All processing stays in your browser.

Reduce file size and polygon count.
Check the detail before you export.

Drop an STL file hereUp to 50 MB · 500,000 triangles · binary or ASCII

Your file stays in this browser. Start with a sample to see the difference.

No uploadNo accountFree exportOriginal preserved

01 / TWO WAYS TO GET SMALLER

Less text.
Or fewer triangles.

Binary conversion preserves geometry

An ASCII STL repeats coordinates as text. Keep 100% of triangles to export the stored coordinates as a compact binary STL. If your input is already binary, this alone may not reduce the file.

STL simplification reduces detail

Set a lower triangle target to merge small geometric details. This is lossy: sharp edges, small holes and dimensions may change. Switch between the original and result, then check the export in your slicer.

02 / SIZE MATH

How much smaller will it get?

Binary STL is 84 bytes plus 50 bytes per triangle. These are exact format sizes, not a promise that every mesh can reach the target.

Binary STL file size by triangle count
Triangles	File size (decimal MB)	Compared with 100,000
100,000	5.000084 MB	Baseline
50,000	2.500084 MB	About 50% smaller
10,000	0.500084 MB	About 90% smaller

03 / A PRACTICAL WORKFLOW

How to reduce STL file size

Choose a file or try the high-detail sphere.
Start at 50% retention and the balanced error limit.
Simplify, compare both previews and inspect the actual output count.
If detail is lost, keep more triangles or lower the error limit.
Download, slice and check thin walls and dimensions before printing.

KNOW WHAT STL STORES

Geometry, not UVs or materials

STL does not carry standard UV maps, materials or units. This tool exports geometry and recalculates normals. It does not retain nonstandard color extensions. Keep your source project if those details matter.

Mesh simplification is not mesh repair. Existing holes or non-manifold edges may remain. Use the STL fixer for simple repairs first. No guarantee is made for self-intersecting or complex meshes.

Powered locally by meshoptimizer, under the MIT license.

04 / FAQ

Before you export

Is STL compression lossless?+

Reducing triangles is lossy. Keeping 100% converts ASCII STL to binary without simplifying the stored geometry. Binary export still uses STL’s 32-bit coordinate precision.

Why did the result stop above my target?+

The error limit, locked boundary vertices and topology may prevent more simplification. We show the actual result, not a guaranteed target count.

Does it keep units, UVs and materials?+

Coordinates are not rescaled, but dimensions can change slightly during simplification. STL has no standard units, UV maps or materials. Normals are recalculated.

How large can my STL be?+

Up to 50 MB and 500,000 triangles, subject to available device memory. All processing happens in this browser. Larger files need a desktop workflow.