STL Scaling Percentage Calculator

Resizing a model to an exact dimension

Downloaded STL models rarely arrive at the exact size you need for a particular fit, enclosure, or replacement part. Rather than guessing at a scale factor in your slicer, work out the exact percentage needed from the model's current dimension and your target dimension.

Worked example

A model's current width (as shown in your slicer) is 100mm, but you need the finished part to be 150mm wide:

Scale % = 150 / 100 x 100 = 150%

Enter 150% into your slicer's uniform scale tool (locking all three axes together) to resize the entire model proportionally.

Frequently asked questions

Should I scale all axes by the same percentage? Yes, for almost all models - uniform scaling preserves the model's proportions and any threads, snap-fits, or mating features designed into it. Non-uniform scaling (stretching only one axis) will distort curved surfaces and can break tight-tolerance features.

Should I account for shrinkage separately? Yes - if your material also shrinks noticeably on cooling, combine this scaling percentage with a separate shrinkage compensation factor rather than trying to estimate both at once.