3D Print Shrinkage Calculator

In short Prints come out slightly smaller than designed, and the fix is to scale the model by the intended size divided by the measured size. The important detail is that the scale factor is not the shrinkage percentage turned around. A part that came out 2% small needs scaling to 102.04%, not 102%, because the two are reciprocal rather than complementary — 100 divided by 98 is 1.0204. The difference sounds trivial and is not: over a 200 mm part it is 0.08 millimetres, and it compounds if you correct twice. Measure across the largest dimension you can. Percentage error shows up most clearly over a long span, and calipers have a roughly fixed absolute error, so trying to detect a 0.5% error on a 20 mm feature asks them for 0.1 mm, which is at the limit of what a cheap pair will tell you honestly. Materials differ a lot — ABS shrinks noticeably, PLA far less — and so do axes, because parts shrink more in the plane of the bed than in Z, and a part clamped to the bed by its own adhesion shrinks differently again. If X and Y are out by different amounts, scale them separately rather than applying one number to everything. Before reaching for shrinkage compensation at all, check the machine. A part that is consistently wrong in one axis is far more likely to be a steps-per-millimetre error than material shrinkage, and compensation applied on top of a miscalibrated axis fixes the part you measured and breaks every other size you print.