How to compensate for shrinkage
- Print a large, simple test part in the filament you want to calibrate, e.g. a 100 × 100 mm hollow square frame or a long bar. Larger parts make small percentage errors easier to measure.
- Let it cool fully to room temperature; most materials keep shrinking as they cool.
- Measure each axis with calipers and enter designed and measured sizes above.
- Apply the scale percentage per axis to models in your slicer, or set it in the filament profile if your slicer supports shrinkage compensation (PrusaSlicer and OrcaSlicer both do).
The formula
scale % = designed ÷ measured × 100
shrinkage % = (designed − measured) ÷ designed × 100
Shrinkage vs. other accuracy problems
- Small holes too small, outer walls too big by a constant amount: that's not shrinkage. Use the slicer's XY hole/contour compensation instead of scaling.
- The same percentage error with every material: likely a mechanical issue such as belt tension, not material shrinkage. Don't "fix" it by changing steps/mm on belt-driven axes unless you have changed pulleys or belts.
- ABS, ASA and nylon generally shrink noticeably more than PLA, so calibrate each material separately.
Frequently asked questions
How much does PLA shrink?
PLA shrinks relatively little, typically a few tenths of a percent, while ABS, ASA and nylon shrink noticeably more. Measure your own filament for an exact value.
Should I scale Z as well?
Usually Z needs little or no correction because layers are stacked at a fixed height, but measure it. If Z is consistently off, check your first-layer squish and Z offset first.