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STL to PLY converter

Turn an STL into a binary PLY for MeshLab, CloudCompare or a scanner's software. The triangles share their corners, and the numbers stay as they are.

60 mm40 mm30 mm

Drop an STL file anywhere on this pageChoose an STL file to convert it

Nothing is uploaded. Binary PLY with the corners shared, standing on Z. Several STL files become one PLY.

The STL to PLY converter with a bracket open: an L-shaped part with three holes, a size of 60 × 40 × 30 mm, a check mark at Watertight, and a Download PLY button with links for 3MF, OBJ, GLB and glTF.
The sample bracket, ready to save as a binary PLY whose triangles share their corners.

What the PLY keeps

In the PLY
ShapeEvery triangle, every corner where the STL put it
CornersShared: each written once, as a vertex of the PLY
SizeThe STL's numbers, unchanged
Which way upStanding on Z, as the model stands on screen
Several filesOne mesh: a PLY has no parts
FormatBinary, little-endian: a float for each number, an integer for each corner of a triangle

Nothing of the shape is lost: an STL is triangles and nothing else, and the PLY holds the same triangles.

How to convert an STL to PLY

  1. Drop the STL on this page, or choose it with the button. Binary and ASCII STL both open. It is read in your browser; nothing is uploaded.
  2. Look at the model and its size. Drop more STL files to put them in the same PLY.
  3. Choose Download PLY. The file is named after the STL: bracket.stl becomes bracket.ply.

Shared corners

An STL writes three corners for every triangle, so a corner where six triangles meet is written six times, and a program that reads it has to find out which corners are the same. A PLY lists each corner once and builds the triangles from their numbers. The converter joins the corners that are the same in every digit, which is how an STL writes a corner that triangles share. None is moved, and two that differ, however little, stay two.

The PLY is smaller than the binary STL for that reason: a corner is 12 bytes once instead of 12 bytes for each triangle that meets there.

Orientation

An STL made for printing stands on Z, and the PLY keeps it so. If the model lies on its side in the viewer, choose the other axis in the Views menu: the PLY stands as the model stands on screen.

PLY, OBJ or STL

A PLY is the format of scans and of MeshLab and CloudCompare, and can hold a color for each vertex. An OBJ is read by nearly every 3D program. To go back, PLY to STL writes an STL for a slicer. The 3MF, OBJ, GLB and glTF are saved from the links under the button.

Questions

Is my file uploaded?

No. The STL is read and the PLY is written by your own browser. Nothing is sent to a server.

Is it binary or ASCII?

Binary, little-endian, which every program that reads PLY takes, and smaller than the same written as text.

Is the shape the same?

Yes, triangle for triangle. Every corner keeps the number the STL gives it. The PLY lists each corner once and builds the triangles from them, where an STL writes it again for every triangle that meets there.

What unit is the PLY in?

The STL's own: neither file states a unit, so the numbers are copied as they are. An STL made for printing is in millimeters.

Can I put several STL files into one PLY?

Yes. Drop them together, or drop more on the open model. A PLY has no parts, so they become one mesh, each where its STL put it.