How do I open an STL file on iPhone or Android?

Open this page in Safari or Chrome, tap Choose file, and pick the STL from Files, Drive, or your downloads. It renders on the phone, and nothing is uploaded.

Why does my STL look tiny or huge?

STL stores no units. A file exported in metres or inches comes out the wrong size in a slicer too. Here, set the file units to see its real size; to fix the file, scale it by 1000 or 25.4 with the STL scaler before you print.

Should I use an STL viewer or a slicer?

A viewer is for a quick look, with nothing to install or set up. A slicer such as Bambu Studio, PrusaSlicer, Cura, or OrcaSlicer lays the part on the bed and writes the G-code. Open the STL there when you are ready to print.

Can I edit an STL here?

Not the triangles: STL is a mesh, and meshes are hard to edit anywhere. To change a part, describe it to Voloom. It builds a parametric model you can resize, then exports a new STL.

Can I measure an STL file?

Yes. Ruler measures between any two points, snapping to corners and edges, and splits the distance into X, Y and Z. Face reads a flat face's width and length, or a hole's diameter. Readouts are in millimeters: STL stores no units, so set the file units if it was saved in inches or meters.

How do I check if an STL is watertight?

Open it here. The panel counts open edges (the rims of holes), edges shared by more than two triangles, and separate parts. A watertight mesh has none of the first two. If it fails, the STL repair tool fixes most files.

Can I show a model on my site or in a GitHub README?

Yes, when the file is online somewhere that lets other pages read it, such as GitHub. Paste its address under "Show a model on your site or repo" for a README badge, an embed for your site, or a plain link. Printables and Thingiverse do not allow it, so download the file and drop it in here.

Do I need to install anything to open STL?

No. It runs in any modern browser, on desktop or phone.

No. The file is read and converted in your browser. It never reaches our servers.

Is the STL viewer free?

Yes, with no limit and no account.

stl viewer

STL viewer online

Open STL files in your browser. Measure distances and holes, cut a section, check it is watertight, and see the print weight. No install, nothing uploaded.

Drop STL here, or choose a file

Stays in your browser. Nothing is uploaded.

Choose file

Good to know

STL has no units, so the size shown is the file's own numbers, and slicers read them as millimetres. A part that measures 0.06 across was saved in metres, and one that measures 2.4 was probably saved in inches: check before you print, and fix it with the STL scaler. The triangle count tells you how fine the mesh is: a few thousand for a bracket, millions for a 3D scan.

How it works

1Drop an STL file in the box above. It opens in your browser; nothing is uploaded.
2Drag to orbit, scroll to zoom, right-drag to pan. Front, Top and Side square the camera up.
3Ruler gives the distance between two points. Face reads the size of a flat face or the diameter of a hole.
4Section cuts across the height, width or depth to show walls and hollows. Size draws the bounding box.
5The panel gives the size in millimeters, whether the mesh is watertight, and what it weighs in PLA.

Show a model on your site or repo

Paste the address of an STL file that is online, such as one in a GitHub repo, and copy what you need. The file stays where it is: each visitor's browser reads it from there.

File address

The badge, as it shows in a README

README badge (Markdown)

For a GitHub or GitLab README.

[![View in 3D](https://www.voloomcad.com/badges/view-in-3d.svg)](https://www.voloomcad.com/tools/stl-viewer?url=https%3A%2F%2Fexample.com%2Fpart.stl)

Embed on a site (HTML)

The viewer with measuring and section, inside your page.

<iframe src="https://www.voloomcad.com/embed/viewer?url=https%3A%2F%2Fexample.com%2Fpart.stl" width="100%" height="420" style="border:0" allow="fullscreen" loading="lazy" title="3D model"></iframe>
<p><a href="https://www.voloomcad.com/tools/stl-viewer">STL viewer</a> by Voloom</p>

Link

https://www.voloomcad.com/tools/stl-viewer?url=https%3A%2F%2Fexample.com%2Fpart.stl

It works when the host lets other sites read the file: GitHub, GitLab and most direct download links do. Printables and Thingiverse do not.

About STL

STL (Stereolithography). The default 3D printing format since 1987: a bare list of triangles. Every slicer reads it, but it has no units, no color, and no parts.

Units: None in the file. Slicers read the numbers as millimeters. Up axis: Z. Opens in Bambu Studio, PrusaSlicer, Cura, OrcaSlicer, and Blender.

Questions

How do I open an STL file on iPhone or Android?: Open this page in Safari or Chrome, tap Choose file, and pick the STL from Files, Drive, or your downloads. It renders on the phone, and nothing is uploaded.
Why does my STL look tiny or huge?: STL stores no units. A file exported in metres or inches comes out the wrong size in a slicer too. Here, set the file units to see its real size; to fix the file, scale it by 1000 or 25.4 with the STL scaler before you print.
Should I use an STL viewer or a slicer?: A viewer is for a quick look, with nothing to install or set up. A slicer such as Bambu Studio, PrusaSlicer, Cura, or OrcaSlicer lays the part on the bed and writes the G-code. Open the STL there when you are ready to print.
Can I edit an STL here?: Not the triangles: STL is a mesh, and meshes are hard to edit anywhere. To change a part, describe it to Voloom. It builds a parametric model you can resize, then exports a new STL.
Can I measure an STL file?: Yes. Ruler measures between any two points, snapping to corners and edges, and splits the distance into X, Y and Z. Face reads a flat face's width and length, or a hole's diameter. Readouts are in millimeters: STL stores no units, so set the file units if it was saved in inches or meters.
How do I check if an STL is watertight?: Open it here. The panel counts open edges (the rims of holes), edges shared by more than two triangles, and separate parts. A watertight mesh has none of the first two. If it fails, the STL repair tool fixes most files.
Can I show a model on my site or in a GitHub README?: Yes, when the file is online somewhere that lets other pages read it, such as GitHub. Paste its address under "Show a model on your site or repo" for a README badge, an embed for your site, or a plain link. Printables and Thingiverse do not allow it, so download the file and drop it in here.
Do I need to install anything to open STL?: No. It runs in any modern browser, on desktop or phone.
Is my file uploaded?: No. The file is read and converted in your browser. It never reaches our servers.
Is the STL viewer free?: Yes, with no limit and no account.
What else opens STL files?: Bambu Studio, PrusaSlicer, Cura, OrcaSlicer, and Blender.

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