What this calculator does
Many printing materials contract slightly as they cool from their printing temperature down to room temperature, or as they cure, and that shrinkage is not always accounted for automatically. ABS is a well-known example among filaments, and it is even more pronounced with many photopolymer resins, where parts can come out visibly smaller than designed unless the model is deliberately scaled up in advance.
The fix is straightforward: scale the model up by exactly enough that after shrinkage, it lands back at the intended dimension. This calculator converts an expected shrinkage percentage into the scale factor to enter in the slicer, and shows what a specific design dimension becomes once scaled.
The formula
Divide 100 by (100 minus the expected shrinkage percentage) to get the scale factor. Multiply any original dimension by that factor to get the value to model or scale to before printing.
| Term | Meaning |
|---|---|
| Expected shrinkage | The percentage a material is expected to contract from its as-printed size to its final cooled or cured size. |
| Scale factor | The multiplier applied to every dimension in the slicer or CAD model to compensate for that shrinkage. |
| Scaled dimension | What an original design dimension becomes once the scale factor is applied. |
The inputs explained
| Field | What to enter |
|---|---|
| Expected shrinkage (%) | The expected shrinkage percentage for the material, typically found from the manufacturer’s data sheet or your own test prints. |
| Original design dimension (mm) | A specific dimension from the original design that you want scaled to compensate for shrinkage. |
When to use it
Printing a precise-fit ABS part
ABS parts that need to mate with another component, such as a bracket or enclosure, often need this compensation to land within tolerance after cooling.
Scaling a resin model before printing
Resin shrinkage during curing is often larger than filament shrinkage, so this compensation matters more for SLA/DLP prints, particularly on larger, flatter parts.
Calibrating shrinkage from a test print
Printing a known dimension, measuring the actual result, and working out the shrinkage percentage from the difference gives a material-specific figure more accurate than a generic published value.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How the scale factor changes with expected shrinkage
A fixed 100 mm design dimension, across a range of expected shrinkage percentages.
| Expected shrinkage | Scale factor to apply in slicer | Scaled dimension to enter |
|---|---|---|
| 0.5% | 1.005× (0.50% up-size) | 100.50 mm |
| 1% | 1.010× (1.01% up-size) | 101.01 mm |
| 2% | 1.020× (2.04% up-size) | 102.04 mm |
| 3% | 1.031× (3.09% up-size) | 103.09 mm |
| 5% | 1.053× (5.26% up-size) | 105.26 mm |
| 8% | 1.087× (8.70% up-size) | 108.70 mm |
Questions
Why is the scale factor not simply 1 plus the shrinkage percentage?
Because shrinkage is defined as a percentage of the final (post-shrink) size being lost from the original printed size, so the correct compensation is 100 divided by (100 minus the shrinkage), not simply adding the percentage back on. The difference is small at low shrinkage but grows at higher percentages.
Where do I find the expected shrinkage percentage for my material?
Manufacturer data sheets sometimes list it, particularly for engineering filaments and resins. Otherwise, printing a known dimension, measuring the result and calculating the percentage difference gives a value specific to your own printer and settings.
Does PLA need this kind of compensation?
Usually much less than ABS or resin, since PLA shrinks comparatively little. It is not entirely immune, particularly over large flat dimensions, but the correction is often small enough to be within normal dimensional tolerance.
Should I scale the whole model uniformly or just one dimension?
Most materials shrink roughly uniformly in all directions, so scaling the whole model by the same factor is the usual approach. Some materials shrink slightly more in one direction (often along the layer direction), which would need a per-axis scale rather than a single uniform one.
Once the scaled model is ready, use the print time estimate calculator to see how the larger size affects print time, or the filament weight and cost calculator to see the effect on cost.