How is the scale factor calculated?

A part designed at dimension D cools to D times (1 minus shrinkage). To finish at the target, the model must be scaled by 1 divided by (1 minus shrinkage). For 1.8 percent ABS shrinkage that is 1 over 0.982, or about 101.83 percent.

What are typical shrinkage rates?

PLA and PETG shrink very little, around 0.3-0.4 percent. ABS is roughly 1.8 percent, ASA 1.5 percent, polycarbonate 0.7 percent, and Nylon up to 2 percent. Glass and carbon-fiber fillers reduce shrinkage compared with the unfilled base resin.

Should I apply this scale in the slicer or in CAD?

Either works for uniform parts. Slicer scaling is fast for a one-off. For parts with mixed internal and external tolerances, compensate in CAD so you can offset holes and pegs independently, since shrinkage affects external dimensions and internal cavities differently.

Why do my ABS parts come out undersized even after compensating?

Shrinkage varies with print temperature, bed temperature, part geometry, and cooling rate. The values here are starting points. Print a calibration block, measure it, and feed your measured shrinkage into the Custom field for a printer-specific result.

Does shrinkage affect holes and pegs the same way?

No. As the part shrinks, external dimensions get smaller but internal holes also get smaller (tighter). For a press fit this can help or hurt depending on which part shrinks. Compensate holes and external features separately when fit is critical.

3D Print Shrinkage & Tolerance Calculator

Tight-tolerance prints in ABS, ASA, or Nylon almost always come out undersized because the material contracts as it cools. This calculator gives you the scale factor to apply so the finished, cooled part lands on your target dimension.

How it works

If a part is modelled at dimension D, after printing and cooling it measures:

printed size = D × (1 − shrinkage)

To make the cooled part equal your target, you must print it larger. Solving for the model dimension:

scale factor = 1 ÷ (1 − shrinkage)

model dimension = target × scale factor

For ABS at 1.8% shrinkage, the scale factor is 1 ÷ (1 − 0.018) = 1 ÷ 0.982 ≈ 1.0183, or 101.83%. A part that must finish at 100mm should be modelled or scaled to 101.83mm.

Typical shrinkage rates

Material	Linear shrinkage
PLA	~0.3%
PETG	~0.4%
PC	~0.7%
ASA	~1.5%
ABS	~1.8%
Nylon (PA)	~2.0%

Glass- and carbon-filled grades shrink noticeably less than their unfilled base resin, which is one reason filled nylons are favoured for dimensionally critical parts.

Tips

Apply the scale uniformly across X, Y, and Z in the slicer for simple parts.
For press fits, compensate holes and pegs separately — shrinkage tightens internal cavities.
The published rates are starting points. Print a 100mm calibration block, measure it with calipers, compute your real shrinkage as (100 − measured) ÷ 100, and enter that in the Custom field for a printer- and filament-specific result. Everything runs locally in your browser.