How to check that an STL file is printable before you print
Open the STL in your slicer and confirm four things: the surface is closed (no open edges), no edge is shared by more than two faces, walls are thick enough for your nozzle, and the part fits the bed with clearance. Our print-check page tests the first two and the fit in your browser without uploading the file.
Closed and manifold
Open edges and non-manifold edges confuse slicers about inside and outside. They are the most common failure in AI-generated and scanned meshes.
Wall thickness
Features thinner than your nozzle width can drop out of the slice. As a floor, keep delicate features at 0.8 mm or more and structural walls at 1.2 mm or more.
Fit and orientation
Allow a few millimetres of bed clearance and try the six axis orientations to find one that needs fewer supports.
Questions
Does the checker upload my file?
No. The print check runs in your browser.
Does a pass guarantee a good print?
No. It checks geometry. Printer, material and settings still decide the result.
Updated November 13, 2026. Prices and competitor terms change; check their sites.