Inspect any STL mesh + quote the print.
Drop a .stl from Bambu / Cura / Fusion. Manifold check, volume / mass / cost estimate, build-plate ghost, AR — all local.
- .stl
- .obj
- .ply
- .3mf
About STL Viewer
Loft STL Viewer opens binary and ASCII STL files in your browser and shows what the print will take: the model's size and volume, the filament it needs, a rough print time and cost, and whether the mesh is watertight. Drop it on a Bambu, Prusa or Ender bed to check the fit. Measure distances, angles and radii, cut a section, and export the model as STL, OBJ or GLB. It also opens OBJ, PLY, 3MF and GLB. The file never leaves your device.
What it does
- Opens binary and ASCII STL, plus OBJ, PLY, 3MF and GLB, up to 200 MB
- Print readiness: size, volume, PLA mass, filament length, and a rough print time and cost
- Watertight check that counts open edges and non-manifold edges
- Build-plate overlay for Bambu A1, A1 mini, P1S and X1C, Prusa MK4 and Ender 3, with drop to plate
- Manufacturability checks for thin walls, draft, undercuts and sharp corners, with a cost estimate for the process and material you pick
- Measure distance, minimum distance, angle, radius, area and wall thickness, and export the results as CSV
- Section view to look inside the part
- Shaded, shaded with edges, wireframe, hidden-line and X-ray views, with one-key front, top and side views
- Exports STL, OBJ, GLB or glTF, a PNG snapshot or a one-page PDF
- View in AR on a supported phone
How to use STL Viewer
Open your STL
Drag a .stl file onto the page, or click Open and pick one. Binary and ASCII files both work. No file to hand? Load the sample cube.
Look around
Drag to orbit, right-drag to pan, scroll to zoom. Press 1 to 6 for front, back, left, right, top and bottom views, and 7 to return home.
Check the print
Open Print readiness for size, volume, filament, print time, cost and the watertight check. Turn on the build plate and pick your printer to see whether the model fits.
Measure
Click Measure, pick a mode such as distance, angle or radius, then click points on the model. Results show in millimetres by default.
Export
Save the model as STL, OBJ, GLB or glTF, or save a PNG snapshot or a PDF sheet of the current view.
Frequently asked questions
How do I open an STL file without installing anything?
Drop it on this page. The viewer opens binary and ASCII STL in your browser, on Windows, Mac, Linux or a tablet, with no slicer, CAD program or account needed. STL files exported from Fusion, SolidWorks, Blender, Tinkercad or a slicer, or downloaded from a 3D model site, all open the same way.
Is my model uploaded?
No. The STL is read and drawn in this browser tab, and the file never leaves your device. You can open a client's part or an unreleased design without sending it anywhere.
What units does it use?
STL files store no unit. Like most slicers, the viewer reads the numbers as millimetres. You can show measurements in centimetres, metres, inches or mils, and the Calibrate tool sets the scale from a length you know.
How does it estimate print time, filament and cost?
From the mesh volume. It assumes PLA at 1.24 g/cm³, 1.75 mm filament, about 30 cm³ printed per hour at 0.2 mm layers, and 22 US dollars per kilogram. Treat the numbers as a first guess; your slicer's estimate, with your infill and supports, is the real one.
Can it tell me whether my STL will print?
It checks whether the mesh is watertight and counts open edges and non-manifold edges, which are the usual causes of slicing errors. The Manufacturability panel also flags thin walls, missing draft, undercuts and sharp internal corners. To repair a broken mesh, use the Mesh Fixer tool.
Will my model fit on my printer?
Turn on the build plate and choose your printer: Bambu A1 mini, A1, P1S or X1C, Prusa MK4 or Ender 3. Drop to plate sets the model on the bed so you can see whether it fits.
Can I convert STL to OBJ or GLB?
Yes. Export saves the loaded model as STL, OBJ, GLB or glTF. The same viewer also opens OBJ, PLY, 3MF and GLB files, so you can convert them to STL too.
What is the largest file it opens?
Up to 200 MB. Very large meshes need more memory, so a desktop browser handles them better than a phone.
Can it open STEP files?
Not this viewer, because STL is a triangle mesh and STEP is exact CAD geometry. Open .step and .stp files in the STEP Viewer, which can also export them as STL.