Scale and rotate STL online — exact dimensions in mm

No file handy?

Dimensions

xmmymmzmm

Rotate 90°

Mirror

Position

How it works

Load the part

The viewer shows it on a print bed with the Z-up convention.

Transform with exact numbers

Type the final width in mm, rotate in 90° steps, or mirror for the left/right version.

Export baked

Operations are applied to the vertices themselves — the STL comes out ready, no metadata tricks.

Frequently asked questions

I downloaded an STL and it's 25× too small — what happened?

Almost certainly it was modelled in inches and your slicer is reading it in millimetres. It is the most common scale problem with downloaded files, and the explanation is simple: mesh formats like STL store no units, only numbers, so whichever program opens the file decides what they mean. The 3D printing convention is that one unit equals one millimetre, but a lot of American CAD software exports thinking in inches, and one inch is 25.4 millimetres: hence the exact factor you are seeing. The inches-to-millimetres button in the ilove3d transform tool multiplies every coordinate by 25.4 and leaves the part at the correct scale. The reverse case exists too: if your model shows up 25 times too large, somebody already converted it and you are converting it a second time. Checking the reported dimensions before sending anything to print is the habit that catches this in seconds rather than after a failed job.

What does 'baking' the transforms mean?

That they are applied directly to the coordinates of every vertex rather than stored as separate data travelling alongside the file. The difference matters. Many formats let you attach a transformation matrix to an object — a rotation, a scale — and leave the geometry untouched, but that relies on whichever program opens the file reading and honouring that matrix. With simple formats like STL the possibility does not exist at all. By baking the transformation, the ilove3d transform tool guarantees that any program opening the file afterwards sees the part already scaled, rotated and seated, without depending on metadata support. It is the only way for the result to be the same in a slicer, in a web viewer and in a CAD package. It is the difference between a file that looks right on your computer and one that looks right on the machine of whoever receives it, which is what matters when sharing.

Does mirroring break the mesh?

No. Mirroring a model also reverses the order in which each triangle's vertices are traversed — the winding, in the jargon — and that is what keeps the normals pointing outward. Without that correction, the mirrored part would have every face turned inside out: it would look identical in a viewer, which draws triangles without asking which way they face, but the slicer would read the interior as exterior and the sliced result would be nonsense. The ilove3d transform tool performs that reversal automatically, so a mirrored model prints exactly as well as the original. It is a detail many mirroring tools skip, and one that surfaces as an inexplicable failure only once you reach the slicer. The same operation is useful for symmetric parts: mirroring one finished half saves modelling the other and guarantees the two match exactly.

What is 'rest on bed' for?

It moves the part so its lowest point sits exactly at Z equal to zero, which is where a slicer expects to find the print bed. Without that, a model can show up floating in mid-air or sunk below the plane on import, depending on where the exporting program had placed the origin. Some slicers correct it themselves on load, others do not, and others correct it in a way that ruins the relative positioning when you are laying out a plate with several parts together. Settling it in the file removes the ambiguity entirely. The ilove3d transform tool bakes that translation along with everything else, so the file arrives ready for any destination without depending on the receiving program having automatic correction enabled. It is worth applying before exporting, because once the part is in the slicer, fixing its height usually means starting the whole placement over again.

Question of the month

Which printer do you use?