PLY to STL

Convert a PLY 3D scan to an STL you can slice and print. Free, in your browser, and the scan is never uploaded.

PLY to STL: from 3D scan to printable file

PLY is what 3D scanners and photogrammetry software produce. Desktop scanners, phone scanning apps, Meshroom, RealityCapture, MeshLab and CloudCompare all write it, because PLY can store a color for every vertex alongside the shape. Slicers don't read PLY. To print a scan, you convert PLY to STL.

The converter reads ASCII or binary PLY in your browser, shows the scan in 3D, and writes a binary STL. The scan isn't uploaded, which matters when it's a person's face or a client's part.

How to convert PLY to STL

1. Drop the .ply onto the converter.

2. Check the preview: a solid surface, not points. Look at the bounding-box size in the info panel to see what units the scan is in.

3. Convert and download the binary .stl.

4. Open it in your slicer. If it's lying on its side or at an angle, rotate it there; scans rarely come in square to the axes.

Mesh or point cloud? Check first

A PLY file can hold a triangle mesh or just a cloud of points. Only a mesh can become an STL, because STL is nothing but triangles.

Drop the file in and look at the preview. A mesh shows a solid surface. A point cloud shows thousands of dots with gaps between them, and the info panel reports zero triangles. The converter will tell you it can't make an STL from it.

To turn a point cloud into a mesh you need surface reconstruction, which this tool doesn't do. In MeshLab or CloudCompare, compute normals, then run Poisson surface reconstruction. Most scanning apps can also export a meshed PLY directly; look for a 'mesh' or 'watertight' export option instead of 'points'.

What survives the conversion

STL is a much simpler format than PLY. The shape comes through intact; the extra data a scan carries does not.

Need the colors kept? Use the PLY Viewer to download it as GLB instead.

Triangles: Kept, with their exact coordinates.
Vertex colors: Lost. STL has no color field for this. The scan's color is what makes it look realistic on screen; the STL will be plain gray. If you need color, keep the PLY or convert to a format like GLB.
Quads and polygons: Split into triangles. STL only stores triangles.
Scale: Unchanged. Scanners usually work in millimeters, so the size carries over. Photogrammetry has no real-world scale unless you used a scale bar or markers, so the numbers can be anything.
Orientation: Unchanged. PLY and STL are both treated as Z-up, so no axis fix is applied.

Scans usually need repair before printing

A valid STL is not the same as a printable one. Raw scans have problems the conversion doesn't fix.

Holes: Wherever the scanner couldn't see (under the chin, the bottom of an object) the mesh is open. Fill holes in MeshLab, Meshmixer or your slicer's repair before printing.
Floating debris: Bits of the turntable, background or stray points meshed into small islands. Delete small disconnected components.
Too many triangles: Scans can have millions of triangles. Binary STL takes 50 bytes per triangle, so a 5-million-triangle scan is about 250 MB. Decimate in MeshLab or Blender first; a few hundred thousand triangles is plenty for most prints.
Paper-thin shell: A scan of a face or a single side is a surface, not a solid. Close it or give it thickness before slicing.
Lying at an odd angle: Scans are oriented however the scanner was. Rotate and place a flat face on the bed in the slicer.

Frequently asked questions

How do I convert PLY to STL?

Drop the PLY file onto the converter, check that the preview shows a surface rather than points, then convert and download the STL. Everything runs in your browser.

Why can't my PLY be converted to STL?

It's probably a point cloud with no faces. STL needs triangles. Mesh the points first with Poisson reconstruction in MeshLab or CloudCompare, or export a mesh from your scanning app.

Does PLY to STL keep vertex colors?

No. STL has no place to store them, so the STL is single-color. Keep the original PLY for color, or download a GLB or PLY from the viewer instead.

Will my scan be uploaded?

No. The file is read and converted on your device and never sent to a server.

My scan is huge. Will it convert?

There's no size cap; the limit is your device's memory. A desktop handles a few hundred megabytes. For printing, though, decimating a heavy scan first makes the STL smaller and the slicer faster.

Why is the STL the wrong size?

The coordinates are copied unchanged, and slicers read STL as millimeters. Scanner output is usually in millimeters, but photogrammetry scans have arbitrary scale. Measure something known on the real object and scale to match in the slicer.