Print Shrinkage Compensation Calculator
Thermoplastic parts shrink as they cool, so a printed dimension comes out slightly smaller than the model. The fix is a scale factor derived from a calibration print: model a known dimension, print it, measure the cooled part, and divide the modeled size by the measured size. This calculator returns that scale factor, the shrinkage percentage, and the slicer scale percentage to enter. Because shrinkage depends on material, geometry, and cooling, it is measured from your own part rather than assumed. You can also enter a target dimension to see the size you should model to hit it.
Shrinkage compensation formula
Scale factor = modeled / measured
Slicer scale (percent) = scale factor * 100
Shrinkage (percent) = (modeled - measured) / modeled * 100
Model size for target = target * scale factor
Multiplying future model dimensions by the scale factor enlarges them just enough that, after shrinking, they land on the modeled size. The factor is derived from your measured calibration part.
Shrinkage context
- Shrinkage is measured from your own part, never assumed from a fixed figure.
- The XY plane and Z height can shrink differently; calibrate per axis where possible.
- Larger calibration dimensions reduce the impact of measurement error.
- A positive shrinkage percentage means the part came out smaller than modeled.
- Apply the scale factor in your slicer or model dimensions larger by that factor.
Shrinkage compensation: frequently asked questions
How do I compensate for print shrinkage?
Print a calibration object of a known modeled size, then measure the cooled part. The scale factor that corrects future prints is the modeled size divided by the measured size. Apply that factor in your slicer's scale field so the printed result matches the model.
Why do prints shrink?
Thermoplastics contract as they cool from the extrusion temperature to room temperature. The amount depends on the material, the geometry, and the cooling, so it is measured, not assumed. This calculator derives the factor from your own calibration measurement.
What is the shrinkage percentage?
Shrinkage percentage is the size lost as a fraction of the modeled size: modeled minus measured, divided by modeled, times one hundred. A positive value means the part came out smaller than modeled; a small negative value means it came out slightly larger.
Should I calibrate separately per axis?
Often yes. The XY plane and the Z height can shrink differently, and some materials are anisotropic. Measure a known dimension on each axis and compute a separate scale factor where your slicer allows per-axis scaling.
How large should the calibration part be?
Larger calibration dimensions reduce the effect of measurement error and surface texture, giving a more reliable factor. A common choice is a 100 mm test bar, but use the largest convenient size your bed allows.
Official sources
- National Institute of Standards and Technology: Office of Weights and Measures (length measurement).
- RepRap project documentation: Calibration guide.
Reviewed by the CalculatorHub team, edited by James Graham, 17 June 2026. See our methodology.