STLPadBinary and ASCII STL supported.
Files from your device are processed locally and never uploaded.
Try a current version of Chrome, Edge, Firefox, or Safari on this browser or device.
ABOUT THIS VIEWER
Drop an STL file into the viewer or choose one from your device. Binary and ASCII STL files are supported, and the model is rendered and analyzed directly in your browser. Local files are not uploaded to our server, no account is required, and geometry analysis runs client-side.
With From URL, a narrowly scoped STLPad relay fetches the remote file temporarily so your browser can process it. Remote models are not stored.
Your device reads, parses and analyzes local STL files in the browser.
Orbit, zoom, fit, measure and review the model before opening a slicer.
Need focused mesh diagnostics? Check your STL, then review supported repair options.
GUIDE
Review X, Y and Z size in the selected display unit.
Inspect volume, surface area and triangle count.
Review watertight, boundary-edge and non-manifold diagnostics.
Use STL Checker for a focused mesh-health report.
Remove supported degenerate and duplicate faces, orient components and safely fill eligible planar holes, with before/after diagnostics.
Use the two-point Measure tool for critical distances.
Compare solid-volume weight estimates for materials.
Check bounding-box fit against supported printers.
Adjust model and background appearance for inspection.
Save a snapshot of the current viewer view.
PRACTICAL WORKFLOW
IMPORTANT DISTINCTION
This viewer can report geometry measurements, topology indicators, visual shape, distance measurements, material estimates and simple printer-bed fit. It does not replace a slicer.
Supports, brim, purge structures, infill, shell thickness, layer height, adhesion and final orientation must still be configured and validated in your slicer.
STL BASICS
STL geometry usually contains coordinates but not reliable physical unit metadata. Many 3D-printing workflows interpret those coordinates as millimeters, but an export or import assumption can create a scale problem.
An inch-to-millimeter mismatch can be approximately 25.4×. A meter-to-millimeter mismatch can be approximately 1000×. STLPad treats raw STL units as millimeters and the unit selector converts displayed values; it cannot recover metadata that the STL does not contain.
MEASUREMENTS
Volume describes the enclosed solid geometry, while surface area describes the triangle surfaces. The viewer uses solid volume and the selected material density to estimate weight.
This is not a slicer filament-use result. Infill, shells, supports and print settings can change actual material usage significantly.
MESH HEALTH
A watertight mesh has a closed surface. Boundary edges indicate open parts of a mesh, while non-manifold edges indicate topology shared in an invalid or ambiguous way. These conditions can cause slicing or printing problems.
The Checker reports common mesh diagnostics. Repair can merge duplicate vertices, remove degenerate and duplicate faces, orient faces consistently, and fill only small, simple planar holes when safe. Ambiguous boundaries and self-intersections may remain unresolved.
PRINTER CHECK
The printer-fit feature compares the model dimensions with supported build volumes and orientation logic. It does not account for every slicer-specific constraint or guarantee printability.
Supports, brim, purge structures and other setup choices may require additional space.
PRIVACY
Files selected from your device stay in the browser and are not uploaded to our server. Parsing, rendering, checking and repair happen client-side, with no registration required. Repair runs in a Web Worker.
Remote URL files pass through a temporary STLPad relay for viewing and are not stored.
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LIMITATIONS
STL units may be missing, and volume is most meaningful for valid closed meshes. Repair is conservative: it fills only small, simple planar boundary loops when triangulation is safe, and does not resolve self-intersections. Repair supports up to 600,000 triangles per model; viewing may handle larger files depending on available browser memory.
Weight is a solid-geometry estimate, and printer-fit results do not replace slicer validation. Final orientation, supports, infill, shell thickness and print settings belong in the slicer.
FAQ
Yes. The viewer is available without an account.
Local files are processed in your browser and are not uploaded to our server.
Yes, both common STL formats are supported.
The current limit is 150 MB for viewing; browser-based repair supports models up to 600,000 triangles.
STL files may not include units. Check the selected unit and the original export settings.
Repair can fill only small, simple planar boundary loops when triangulation is safe. Complex or ambiguous boundaries may remain open, and self-intersections are not resolved. See supported repair options.
Use STL Checker to review boundary edges, non-manifold edges and degenerate triangles.
Yes. Measure two points on the mesh to get their 3D distance.
Yes, the viewer checks bounding-box fit against supported printer volumes.
Yes, it provides a solid-volume estimate based on material density.
No. Use a slicer for supports, infill, shells and final print validation.