Cut STL online for free

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Cut plane

Axis

Plane position0.00 mm

Needs a closed mesh. Each part comes out with the cut capped, without connectors.

What this tool does

Cut with a plane perpendicular to X, Y or Z, moved along the axis with a slider that shows its position in millimetres, and get back both halves.

Every cut face is capped: the contour is rebuilt, triangulated and closed on both parts with opposite normals, so each half is watertight and slicer-ready.

Hollow models are handled correctly — nested contours are detected and the cap is built as a ring instead of a disc, so vase and tube walls keep their thickness.

Accepts STL, OBJ, PLY, GLB and 3MF and exports STL; the file is read locally in the browser, with no upload, no account and no cost.

How it works

Load the model

Drop an STL, OBJ, PLY, GLB or 3MF file onto the page, or open the sample vase included with the tool. The file is read locally in your browser and never sent anywhere. The mesh has to be closed: open and non-manifold meshes are refused, with the check running at the moment you split.

Place the cut plane

Pick the axis the plane should be perpendicular to — X, Y or Z — and drag the slider to move it along that axis. The plane is drawn over the model and its position is shown in millimetres, so you can line the split up against a build-plate limit or a feature of the part.

Split and download

Press split. The cut runs in a Web Worker, so the page stays responsive on large meshes. Preview both parts separated or one at a time, then download each side as an STL with the cut face closed. The separation you see is preview-only; each part is exported where it sits.

Frequently asked questions

How do I split an STL file in half online?

Open the Cut model tool on ilove3d, drop in your file, and pick the axis the plane should be perpendicular to: X, Y or Z. A slider moves the plane along that axis and shows its position in millimetres, so you can see where the split will land instead of guessing at the midpoint. Press split and the engine returns both halves, each one capped: the contour where the plane crossed the mesh is rebuilt, triangulated and closed on both sides with opposite normals, so neither part comes out as an open shell. You can preview each side on its own and download them as STL files, one at a time. Accepted inputs are STL, OBJ, PLY, GLB and 3MF; output is always STL, which every slicer reads. A sample vase is included if you want to test the workflow before loading a model of your own. No sign-up or install is required.

How can I print an object larger than my build plate?

Split it into pieces that each fit inside the printable volume, then glue or bolt the printed parts together. In practice: measure your printer's bed and height, open Cut model on ilove3d, load the STL and choose the axis that crosses the longest dimension. Move the plane until each side is under the machine's limit; the position is shown in millimetres, so you can work it out against the model's own dimensions. Both halves come back closed, which matters because a slicer will refuse or misinterpret a half that is still an open shell. Cut model does not rotate anything, so lay the new flat face down in your slicer; that orientation usually needs less support than the original overhang did. For a part that is long in two directions, download a half, load it back in and cut again on the other axis. No pins or registration keys are added, so plan the alignment yourself.

Why is my model open after cutting it, and how do I get a closed flat face?

Keeping the triangles on one side of a plane is the easy part, and it is all that a simple trim operation does: the result is a shell with a hole where the plane passed, and slicers reject it or fill it unpredictably. Cut model on ilove3d rebuilds the missing surface instead. It collects every point where the plane crosses a face, chains those segments into closed loops, triangulates the loop and emits the same cap twice with opposite winding, so one half is sealed looking up and the other looking down. Hollow parts produce two nested loops rather than one, so the cap becomes an annulus rather than a disc; nesting is worked out from loop area and a point-in-polygon test. Collinear points that triangulation would skip are removed first and put back edge by edge, which prevents the hairline T-junction crack where the cap meets the original wall.

Is my file uploaded to a server when I cut a 3D model online?

No. Your file never leaves your machine. Cut model runs in the browser on ilove3d: the file you drop in is read locally through a blob URL, the geometry is computed on your own computer and drawn with WebGL, and the resulting STL is written by the same page you are looking at. There is no upload, no queue and no copy of your model left sitting in someone else's storage. The heavy work happens inside a Web Worker, which is a background thread in your browser rather than a remote machine; that is why the interface stays responsive on large meshes instead of locking up. Two practical consequences: speed depends on your own hardware, and you can cut confidential or client-owned geometry without needing a transfer agreement. There is no account, no sign-up and no charge, and closing the tab discards everything, so save the parts you want.

Why do I get an error saying my mesh has open edges?

Cut model checks that the mesh is closed and refuses to cut it otherwise. The test is simple: in a watertight solid every edge belongs to exactly two faces. An edge used once means there is a hole; an edge used three or more times means the surface is non-manifold, with faces overlapping or joined along a seam. In either case there is no way to tell inside from outside, and therefore no way to know what the cap should cover, so ilove3d stops rather than returning a broken result. The check runs when you press split, not when the file loads. Send the file through the repair tool on the site first, then cut it. A different message says the cut could not be closed, which points at a contour the engine could not resolve; moving the plane slightly and retrying usually clears that one. Meshes above roughly one million triangles are also refused.

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