How much does PLA shrink? Rate, Z and the value to enter

PLA (polylactic acid) shrinks about 0.5% in X and Y and 0.8% in Z as a printed part cools, so a 100 mm PLA part comes out roughly 99.5 mm long. Molded PLA resin shrinks 0.4%, according to NatureWorks.

How much does PLA shrink?

Printed PLA shrinks roughly 0.35 to 0.8%. In a Binghamton University study, PLA parts lost 0.63% in X, 0.35% in Y and 0.80% in Z. That averages about 0.5% across X and Y. NatureWorks lists 0.4% molding shrinkage for its Ingeo 3052D resin. Your own printer and settings will move these numbers.

Source	Shrinkage	Lost on 100 mm	Lost on 25 mm
Printed PLA, X	0.63%	0.63 mm	0.16 mm
Printed PLA, Y	0.35%	0.35 mm	0.09 mm
Printed PLA, Z	0.80%	0.80 mm	0.20 mm
Molded PLA resin (no axis given)	0.4% ± 0.1%	0.40 mm	0.10 mm

The printed figures come from Weiser et al. (2021). They printed three part designs three times each in PLA on a QIDI X-One2 and measured them with digital calipers. That is nine PLA parts on one printer, so treat the figures as a starting point, not a constant. X and Y differed by almost half in that study, which is why a single XY number is a compromise.

The molded figure comes from NatureWorks’ sheet for Ingeo 3052D: 0.004 in/in, plus or minus 0.001. It describes melt packed into a steel mold under pressure. That says how the polymer behaves, but it gives no Z value and does not predict a printed part.

Does PLA shrink when it cools?

Yes. Bambu Lab’s wiki describes print shrinkage as thermal contraction: the plastic leaves the nozzle hot and contracts on its way down to room temperature, mostly in X and Y. Its test procedure says to measure only once the part has cooled to room temperature.

Whether 0.5% matters depends on the size. On a 20 mm part it is 0.1 mm. On a 200 mm part it is 1 mm, enough to stop a lid or a joint from fitting.

What shrinkage compensation should you use for PLA?

Start with 0.49% in X and Y and 0.80% in Z, the averages from the Binghamton study. That means 99.51% and 99.20% in OrcaSlicer, 99.51% in Bambu Studio, 0.49% and 0.80% in PrusaSlicer, or a model scale of 100.49% and 100.81%. Then measure your own test part and replace them.

Where	Field	X and Y	Z
OrcaSlicer	Filament: Shrinkage (XY), Shrinkage (Z)	99.51%	99.20%
Bambu Studio	Filament settings, Basic information: Shrinkage	99.51%	no field; scale the object’s Z to 100.81%
PrusaSlicer	Filament: Shrinkage compensation XY, Z	0.49%	0.80%
Any slicer’s scale tool	Object scale	100.49%	100.81%

The fields expect different numbers:

• OrcaSlicer and Bambu Studio want the cooled size as a percentage of the design. Their tooltip example is “94% if you measure 94mm instead of 100mm”. Both default to 100%, which means no compensation, and Bambu Studio’s field scales X and Y only.
• PrusaSlicer wants the shrinkage itself: “if you measured 99mm instead of 100mm, enter 1%”. It defaults to 0%, accepts -10% to 10%, and shows the fields in Advanced and Expert mode.
• Model scale wants the scale factor, 1 / (1 - shrinkage). For 0.49% that is 1 / 0.9951 = 1.0049, or 100.49%.

Use one method, not two. A shrinkage value in the filament profile plus a scaled model compensates the part twice.

How to account for PLA shrinkage on your own printer

1. Calibrate flow first. Thin or fat walls shift every outside dimension by the same fixed distance, which is not shrinkage. The guide to dimensional accuracy calibration covers the order.
2. Print a test part in the PLA you use, at least 100 mm long in X and Y and tall enough to measure Z. On 100 mm, 0.5% is 0.5 mm, easy to read with calipers.
3. Let it reach room temperature, then measure each axis.
4. Compute shrinkage as (designed - measured) / designed. A 100 mm side that measures 99.45 mm has shrunk 0.55%: enter 99.45% in OrcaSlicer or Bambu Studio, 0.55% in PrusaSlicer, or scale the model to 100.55%.

The shrinkage compensation calculator does that arithmetic for each axis and shows the value for each slicer field.

Does PLA+ shrink differently from regular PLA?

None of the PLA+ makers checked for this page publishes a figure showing it shrinks differently. Sunlu lists the same 0.1 to 0.3% for its PLA, PLA+ and PLA+ 2.0 and names no test method. The data sheets for eSUN PLA+, Overture PLA+ and PLA Pro, and Polymaker PolyLite PLA Pro give no shrinkage figure at all.

Filament	Published shrinkage
Sunlu PLA, PLA+, PLA+ 2.0	0.1 to 0.3%, method not stated
eSUN PLA+ (data sheet V4.0, 2021)	None
Overture PLA+ (V5.2) and PLA Pro (V5.1)	None
Polymaker PolyLite PLA Pro	None
Elegoo PLA+	None; the product page says only that it “minimizes warpage and shrinkage”

Sunlu’s range sits below both the printed-part figures (0.35 to 0.80%) and the molded resin figure (0.4%). Since Sunlu does not say how it was measured, do not enter it as a calibration value.

PLA+ and PLA Pro are not one material. Each maker modifies PLA its own way (eSUN describes its PLA+ as “modified based on PLA material”), so one brand’s result says nothing about another’s. Start PLA+ at the PLA values, then measure each brand with the steps above and save the result in that filament’s profile.

What PLA shrinkage compensation does not fix

• Holes. Undersized holes come from polygon facets and extrusion width, not material shrinkage. Use the slicer’s X-Y hole compensation instead of scaling.
• Annealing. Heat-treating PLA shrinks it far more than printing does. CNC Kitchen reported about 10% shrinkage in X and Y, with growth in Z. The calculator can stack an annealing step on top of print shrinkage.
• Other filaments. In the same Binghamton study, PETG (polyethylene terephthalate glycol) shrank 0.54 to 0.76% in X and Y. ABS (acrylonitrile butadiene styrene) grew 0.92% in Z. A PLA value does not carry over to either.