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3DPrintMates

Free online STL viewer

Open an STL, 3MF, OBJ or GLB file to rotate it in 3D and check its real-world size, volume and triangle count before you slice or send it to a print shop.

View.stl.obj.3mf.glbRuns locally

Preview appears here

Drag to orbit · scroll to zoom · right-drag to pan · grid = 10 mm

Drop a file here or

.stl, .obj, .3mf, .glb · processed on your device, never uploaded

How to use the STL Viewer

  1. 1Drop a file onto the viewer, or click browse.
  2. 2Drag to orbit, scroll to zoom, right-drag to pan. The grid squares are 10 mm.
  3. 3Check the size panel. If it looks 25× too small, the file is probably in inches - change "File units".
  4. 4Toggle wireframe to spot dense or broken areas of the mesh.

What to check before printing an STL

  • Size: does the largest dimension fit your printer's build volume? Many common desktop printers have a bed between about 180 and 256 mm.
  • Units: a phone stand that measures 3.5 × 2.8 × 4.7 "mm" was exported in inches.
  • Orientation: the flattest large face usually goes on the bed to reduce supports.
  • Triangle count: millions of triangles slow slicers down without improving a typical FDM print.

STL, 3MF, OBJ and GLB in one viewer

STL is the most common format for printable models, while 3MF is used by Bambu Studio, PrusaSlicer and Cura project files. OBJ and GLB usually come from 3D modeling and scanning apps. If you need to change formats, use the 3MF to STL, OBJ to STL or GLB to STL converters. To learn the difference, read STL vs 3MF.

Frequently asked questions

Is this STL viewer free?

Yes. It is free with no account, no watermark and no file limit beyond what your device can handle. The model is read by your browser and never uploaded.

Which file types can I open?

STL (binary and ASCII), 3MF, OBJ and GLB. Self-contained glTF files also work; glTF files that reference external .bin or texture files do not.

Why is my model the wrong size?

STL files store numbers without units. Most are in millimeters, but some CAD and 3D-scanning apps export in inches, centimeters or meters. Change "File units" until the dimensions match the real object.

How is volume calculated?

Volume is computed from the closed surface of the mesh. It is accurate for watertight models. If the mesh has holes, the number is unreliable - repair it first.

Can I view STL files on a phone?

Yes. Any modern mobile browser with WebGL can open files; very large models (several million triangles) may be slow on older phones.