# STL to PLY Converter

> Hand STL files to MeshLab, CloudCompare or a scanning pipeline as compact binary PLY with shared vertices.

Page: https://printpal.io/convert/stl-to-ply
Updated: 2026-11-12
Use it: open https://printpal.io/convert/stl-to-ply in a browser and drop a file. Free, no account, files are processed locally and never uploaded.

Some mesh-processing and inspection tools work best with PLY. The converter welds the STL's loose corners into shared vertices and writes binary little-endian PLY, typically under half the size of the STL.

Units and orientation pass through unchanged, since neither format fixes them: an STL in millimetres becomes a PLY in millimetres, Z up. Switch the up axis in the options if the next tool expects Y up.

## How to convert STL to PLY

1. **Drop your STL files.** Drop one or more .stl files, binary or ASCII, or a .zip of them.
2. **Check the preview.** The model appears at the size and orientation it will have. Fix the file units, up axis or size under Size, units and orientation if needed.
3. **Choose PLY options.** Binary little-endian PLY with vertex colors when the model has them. Pick the up axis your next tool expects.
4. **Convert and download.** One file downloads straight away. A batch gives a download per file and one .zip of all of them.

## What carries over

| | Result |
|---|---|
| Geometry | Every triangle is kept at full precision. |
| Color | STL has no color to carry. The PLY comes out uncolored. |
| Units | PLY stores no units. The numbers stay in the unit the STL was read in (millimetres); you can change that in the options. |
| Orientation | Kept the way the STL had it. Switch to Y up (Blender, game engines) or Z up (slicers, CAD) in the options. |
| Objects | Merged into one mesh: PLY has no objects. |

## STL at a glance (Stereolithography (Standard Triangle Language))

Created by 3D Systems in 1987 for the first stereolithography printers, STL is still the format every slicer and print service accepts. It describes a surface as a list of independent triangles, with no shared vertices, units, colors or scene structure.

- **Stores:** Loose triangles: three corners and a normal each, binary or ASCII
- **Color:** None in the standard
- **Units:** None written; slicers assume millimetres
- **Up axis:** Z, the slicer convention
- **File size:** 50 bytes per triangle in binary, about 5 times that as ASCII
- **Opens in:** Every slicer, CAD tool and 3D app

## PLY at a glance (Polygon File Format (Stanford Triangle Format))

Greg Turk designed PLY at Stanford in the 1990s for 3D scan data, and it is still what scanners, photogrammetry tools and MeshLab write. It can hold a colored mesh or a bare point cloud, and Gaussian splat captures reuse it for splats.

- **Stores:** Vertices with any properties, optional faces; ASCII or binary
- **Color:** Per-vertex colors
- **Units:** None; scanners usually write metres
- **Up axis:** Varies with the scanner or app
- **File size:** Binary is compact; ASCII is several times larger
- **Opens in:** MeshLab, CloudCompare, Blender, scanning and photogrammetry software

## Tips

- **MeshLab** Welded PLY lets MeshLab's filters (smoothing, decimation, hole filling) work on a connected mesh.
- **Comparing scans** CloudCompare can compare the PLY against a scan to check a print's accuracy.
- **ASCII PLY?** Binary is smaller and read everywhere. MeshLab can re-save as ASCII if a tool needs it.

## FAQ

### Why convert STL to PLY?

For tools that prefer PLY, for a welded mesh, or for a smaller file. PLY can also carry vertex colors that STL can't.

### Is the PLY binary or ASCII?

Binary little-endian, the most compact and widely read form.

### Does it change the size?

No. The numbers pass through unchanged.

### Is the converter free? Are there limits?

Free, with no sign-up, watermark or file count limit. Batches and files of a few hundred MB work on most laptops; the only limit is your device's memory.

### Are my files uploaded?

No. Files are read and written by JavaScript and WebAssembly in your browser and never sent to PrintPal. The STEP and IGES reader is the only extra download, once, from a public CDN.

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