How to Compensate for 3D Print Shrinkage

A 3D printed part can measure smaller or larger than the dimension in CAD. The difference is often called shrinkage, although the final result can also be affected by extrusion, cooling, orientation and calibration.

The reliable way to compensate is not to copy one universal PLA, PETG or ABS percentage. Print a small test with the same printer, material and profile as the intended part, measure it, and calculate the adjustment from that result.

The 3D Print Shrinkage Calculator keeps the calculation separate for X, Y and Z and gives a compensated model dimension for a target final size.

Print and measure a simple calibration test

Use a part with clearly measurable straight features in all three axes. A 20 mm cube is a simple starting point, though a test that resembles the final part’s size and orientation is more representative. Measure with suitable calipers after the part has cooled and any intended post-processing is done.

1. record the designed test dimension for X, Y and Z;
2. record the printed measurement for each axis;
3. keep the printer, filament, orientation and slicer profile with the measurement;
4. repeat the test if the part is important or the result is surprising.

Calculate the scale factor

The compensation is based on the ratio between the original design and the printed measurement:

Scale factor = designed test dimension ÷ measured print dimension

If a 20.00 mm feature measures 19.80 mm, the scale factor is 20 ÷ 19.8 = 1.0101, or 101.01%. To aim for a 50 mm final feature under the same conditions, model or scale it to about 50.505 mm.

A positive shrinkage percentage means the printed test was smaller than its CAD dimension. A negative percentage means it printed larger. Neither result is automatically a defect: first confirm the measurement and whether it is representative of the final part.

Keep X, Y and Z separate when needed

A single uniform scale is convenient, but it can hide an axis-specific result. Bed adhesion, cooling, layer stacking and part orientation can affect the result differently across the axes. If X and Y agree but Z does not, use the axis-specific values as a starting point and verify with another test before applying them to a critical model.

Shrinkage is not clearance

Whole-model compensation does not make every hole, pin or snap fit correct. Those features also depend on extrusion width, bridging, orientation and the clearance you actually need between mating parts. Use the Tolerance and Clearance Calculator for those dimensions, then validate the final exported model with the STL Dimensions Checker.

Use measured values as a starting point, not a guarantee

A calibration factor belongs to a particular printer, filament, profile and geometry. Changing nozzle settings, material batch, temperature, cooling or orientation can change the outcome. Test important fits and large dimensions again, especially after changing a slicer profile.