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3DAI
Free · runs in your browser · files stay on your device

STL Center of Mass Calculator

Drop a model to see whether it will stand up once printed. The tool finds the centre of mass, drops a plumb line to the table and checks it lands inside the base, with the margin in millimetres and the angle it can lean before it tips. If it falls, it lists the sides it can rest on and the base size that would hold it. Nothing is uploaded.

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How to check if your print will stand

  1. 1

    Drop your model

    Drag an STL, OBJ, 3MF or GLB onto the tool, or press Choose file. It is read in your browser and never uploaded.

  2. 2

    Set your infill

    Enter the infill and wall thickness you will print with. A part printed at 15% infill balances differently from a solid one, and the tool moves the centre of mass to match.

  3. 3

    Read the verdict

    Green stands firmly, amber stands but tips easily, red falls over. The plumb line shows where the weight lands, and the white edge is the one it would tip over.

  4. 4

    Fix it if it falls

    Turn it to another side from the list, or add a base of the size shown. Then check again before you slice.

What the numbers mean

Worked out from the mesh in your browser for the pose you pick. They assume one material of even density on a level table; infill, supports left on and paint move the real balance point a little.

Centre of massThe balance point of the model, from the whole closed volume (as if printed solid) and from the outer skin alone (as if printed hollow). Your print sits between the two; the tool places it from your infill and wall settings.
BaseEvery point within a fraction of a millimetre of the lowest point, wrapped in an outline: the area the print rests on, coloured under the model. Separate feet count as one base, as on a table.
MarginHow far, in millimetres, the plumb line from the centre of mass lands inside the nearest edge of the base. Negative means it lands outside, so the print falls over.
Tip angleHow far the print can lean before it falls: the angle whose tangent is the margin over the height of the centre of mass. 10 degrees or more is marked as standing firmly.
Can rest onThe flat sides of the model's outer shell (as if shrink-wrapped) it can lie on without rolling off, the most stable first. Click one to see it.

How to make a print stand

Make the bottom heavier

Print the base with more walls or a higher infill than the top. In most slicers a modifier or a height-range setting does this, and it pulls the real centre of mass down.

Add a wider base

A disc or plinth under the feet moves the edges out past the plumb line. The tool shows the diameter that would hold your model.

Hollow the top

Heavy heads, arms and props that reach forward are what pull figures over. Less infill or a hollow up there helps as much as weight below.

Mind the feet

Small or rounded feet touch the table in a few points only. Flatten the soles, or glue the print to a base, for display pieces that must not move.

Falls over? Fix it or make a sturdier one

Add a base under the feet to widen what it stands on. Or, for a figure made from a photo, generate a new one with AI in a pose with the weight over the feet, then check it here again. The AI generators use credits; this checker and the base tool do not.

Add a base to the STL →Photo to 3D figurineImage to 3D model

More free 3D printing tools

STL volume and weight calculatorPrint orientation optimizerAdd a base to an STLWall thickness checkerSTL repairSTL viewer

Center of mass FAQ

It stands when its centre of mass is directly above its base. Drop the model into the tool: it finds the centre of mass, drops a plumb line to the table and checks it lands inside the outline of the feet or base. It also shows the margin to the nearest edge, so you know whether a small knock would tip it.
From the closed mesh, using the standard divergence-theorem sums: every triangle and a fixed point form a small tetrahedron, and the volume-weighted centres of all of them give the centre of the solid. It is exact for a watertight model of even density. The hollow (skin only) centre is the area-weighted centre of the triangles.
Yes. A print is solid walls around sparse infill, so it weighs more near its surface than a solid part would. The tool mixes the solid centre and the skin centre by your infill and wall thickness. It is a good first estimate; patterns, top and bottom layers and supports left on the part shift it a little more.
Any positive margin means it stands on a level table. 10 degrees of tip angle or more is marked as firm: it survives a small knock or a sloping shelf. Below that it is marked as tippy, and a wider or heavier base is worth adding for a display piece.
Add a base: the tool gives a diameter that would hold it, and the add base tool can make one. Or print the bottom with more walls and infill, hollow the top, or turn it to one of the sides it can rest on. For a figure made with AI, generating a pose with both feet under the body also works.
The solid centre of mass is exact only for a closed mesh. Holes or loose faces make it an estimate, which is usually close for small holes. Fix the mesh with the STL repair tool and check again if the margin is small.
No. A print orientation tool picks how to place the part on the print bed to need fewer supports while printing. This page checks whether the finished part stands up by itself on a table or shelf, which is about the balance point and the base.
Nothing is uploaded: the file is read and checked in your browser, in a background thread. The tool is free with no account, and the results are yours to use for personal and commercial work, no attribution needed.

Free for personal and commercial use, no attribution. Results are estimates for a uniform material; check important display pieces with a test print.