Model Scale Calculator
Resize a model and see what it does to the material.
Scale
Effect
About the Model Scale Calculator converter
Scaling a model is the one bit of printing arithmetic that reliably catches people out, because the material does not follow the scale — it follows the cube of it.
Enter a percentage, or the size you have and the size you want, and see what happens to the dimensions, the surface area and the filament.
Why 200% costs eight times as much
Doubling every dimension doubles the width, the depth and the height. The volume is all three multiplied together, so it goes up by two cubed — a factor of eight.
That is the difference between a print finishing and a spool running out overnight. It works the other way too: dropping to 50% needs only an eighth of the plastic, which is why test prints are so cheap.
Shrinkage is a division, not a subtraction
ABS shrinks as it cools and resin shrinks as it cures, so a part printed at nominal size comes out slightly small. Compensating means printing it proportionally larger.
The instinct is to add the percentage back, and that is wrong. To finish at size after 2% shrinkage you print at 102.04%, not 102% — because you are dividing by 0.98, not adding 0.02. On a part that has to fit something, the difference shows.
Print time is not so simple
Time roughly follows volume, so it is shown scaled that way, but the relationship is not exact. The outer walls scale with area rather than volume, and travel moves barely change at all.
For a rough plan the cube is close enough. For anything that has to be ready by a deadline, re-slice it.
Frequently asked questions
How do I scale to a specific height?
Enter the measurement you have and the one you want, as "50 to 75". That gives the percentage to type into your slicer.
Does this change my STL file?
No, it works out the number for you. Scaling is a single field in every slicer, and doing it there keeps the original file intact.
How much shrinkage should I allow?
It varies by material and by how the part cools, so measure rather than guess: print a known cube, measure it with callipers, and use the difference. ABS is often around 0.5–2%, and resin varies widely between brands.