Print Shrinkage Compensation Calculator

How the scale factor is worked out

Shrinkage is the difference between the size you designed and the size that came off the plate, written as a percentage of the designed size. The scale factor is the same measurement turned into the number a slicer wants: multiply the model by it, and the printed part lands on size.

shrinkage % = (nominal − measured) ÷ nominal × 100

scale factor = nominal ÷ measured

Worked example: a 20.00 mm nominal feature measures19.82 mm on the printed part.(20.00 − 19.82) ÷ 20.00 × 100 = 0.90%shrinkage, and 20.00 ÷ 19.82 = 1.009082, so the scale to apply is 100.91%.

This is the same target-over-measured ratio OrcaSlicer guides use to correct flow from a measured wall, applied to dimensions instead of extrusion. When you measure more than one axis, the uniform factor the page suggests divides the nominal size by theaverage of your measurements, because the factor is a ratio of two lengths and averaging the lengths keeps that basis reproducible by hand.

Printing something worth measuring

1. Print a part whose designed size you know exactly — a plain calibration cube or a simple block from your own model — in the filament and with the profile you intend to use.
2. Let it cool to room temperature. Dimensional readings taken warm are larger, and a part pulled off the plate early can spring back.
3. Measure outside faces with calipers, at two or three places along the same feature, and average the readings. For Z, measure the height and keep any first-layer flare out of the jaws.
4. Enter the nominal size of the feature you measured and the measured dimensions here. Leave an axis blank if you did not measure it.
5. Apply the factor, print the part again and measure it. If the second part still lands off size, the cause is usually a different one from shrinkage.

What scaling can and cannot fix

• It corrects proportional error, not warping. A scale factor stretches the whole object evenly. Warping is local — lifted corners, bowed walls, oval holes — and no single factor removes it. Enclosure, bed temperature and part cooling are the tools for that.
• It scales holes and clearances too. When you scale a part up, every hole, slot and press fit grows with it, and holes already print undersize for reasons of their own. Check a fit-critical feature after compensating instead of assuming it followed.
• It uses one measurement of one feature. Shrinkage is a property of material, geometry and cooling, not a constant. A 20 mm coupon and a 200 mm bracket do not shrink by the same percentage.
• It does not diagnose mechanical error. Belt tension, loose pulley grub screws, steps-per-mm settings, a worn nozzle and an over-extruding flow ratio all show up as the wrong dimension. If X and Y disagree, fix the mechanics rather than scaling the axes apart.
• It is arithmetic on your own numbers. A misread caliper or a nominal size taken from the wrong model gives a confidently wrong factor. Re-measure before you commit a preset to production parts.

Applying the factor in OrcaSlicer

Scaling in OrcaSlicer happens per object: select the part on the plate and open the scale tool, where you can keep the scale uniform or set each axis separately. Enter the percentage this page gives you — the uniform value when the axes agree, or the per-axis values when they do not. Nothing is written into the filament profile by scaling, so record which filament and profile the measurement belongs to and repeat the measurement when you change material or printer.

Compensating with the model is also the more portable option for a part you model yourself: apply the factor in CAD, or edit the model parameters, and the correction travels with the file instead of sitting in one project. Whatever route you take, keep the printed measurement with the preset — the next spool of the same material will not necessarily shrink by the same amount.

Frequently asked questions