Print Shrinkage Compensation Calculator
Dial in dimensional accuracy when a print comes out slightly under- or over-size. Enter the size you modelled and the size you actually measured, and this calculator gives the scale factor to apply in your slicer or CAD, the percentage shrinkage or expansion, and — if you want a specific final size — the exact dimension to model the feature at.
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How to use this calculator
- Print a calibration part, then measure a known feature with callipers.
- Enter the intended (modelled) dimension and the measured printed dimension, both in millimetres.
- Optionally enter a target final dimension to get the size you should model it at to hit that number after shrinkage.
How it works
The scale factor is the intended dimension divided by the measured dimension, expressed as a percentage — apply it uniformly in the slicer or scale the model in CAD to bring parts back to nominal. Shrinkage is the difference between intended and measured as a percentage of the intended size, where a positive number means the part came out small (shrank) and a negative number means it came out large (expanded). To land a specific final size, multiply your target by the intended-over-measured ratio to get the compensated modelling dimension.
Worked example
Worked example. A feature modelled at 100 mm measures 99.5 mm after printing. The scale factor is 100 ÷ 99.5 × 100 = 100.5025%, and the shrinkage is (100 − 99.5) ÷ 100 × 100 = 0.5%. To end up with a 50 mm feature at that same shrinkage, model it at 50 × (100 ÷ 99.5) = 50.2513 mm.
Common mistakes
- Calibrating on a tiny feature — measurement error is a bigger share of a small dimension, so use the largest test length you can and re-measure to confirm.
- Applying one scale factor to every material and colour — shrinkage differs between filaments and resins, and even between colours, so recalibrate when you change material.
- Confusing scale factor with shrinkage percentage — a 0.5% shrinkage needs roughly a 100.5% scale factor, not a 99.5% one, because you are dividing by the smaller measured size.
Frequently asked questions
Should I apply the scale factor to all three axes?
Not necessarily. Shrinkage is often different in X/Y versus Z, and Z is usually governed by layer height and steps rather than material shrink. Calibrate and apply compensation per axis where your slicer allows it, rather than assuming a single uniform factor is correct for every direction.
Why compensate the model instead of just scaling the whole print?
Scaling the whole print works when the error is a constant percentage, but real parts often have a fixed offset (from nozzle width, elephant's foot or hole-tolerance effects) as well as percentage shrinkage. For critical fits, combine this percentage compensation with a separate tolerance/offset test so holes and mating features end up the right size.
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