Material shrinkage calculator
Plastic shrinks a little as it cools. Type the size you drew and pick the material to get the scale to set in your slicer.
Your part
Typical values for FDM prints. Real shrinkage changes with the brand, the shape, the enclosure and the bed, and long parts often shrink more along their length.
Measure your own
Worked example
An ABS part drawn 100 mm long, at 0.7% shrinkage: scale 100 / (1 - 0.007) = 100.7%. It prints at 100.7 mm and cools to 100 mm. Without the scale it would end at 99.3 mm.
How it works
- Scale % = 100 / (1 - shrinkage).
- It prints at = designed size / (1 - shrinkage).
- Your own shrinkage = (designed - measured) / designed.
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Questions
Should I scale every part?
Only when the size matters, such as parts that fit other parts. PLA shrinks so little that most prints need nothing. ABS, ASA and nylon are worth it for fitted parts.
Why not just add the shrink %?
For small numbers it is nearly the same (100.7% against 100.705%), but dividing by (1 - shrinkage) is exact: the printed size times what is left after shrinking gives back the size you drew.
Holes still come out small. Why?
Holes shrink for other reasons too: the slicer's straight edges cut inside the curve, and lines squash inward. Many slicers have a hole or XY compensation setting for that; scaling the whole part does not fix it.