3D Printing Quality Formula for Small-Scale Prints
Learn how the small-scale 3D printing quality score, layer-height target, layer count, and feature-to-line ratio are calculated.
This calculator estimates whether selected FDM or FFF settings are suitable for fine details on a small model. It combines vertical detail from layer height with horizontal detail from the smallest feature relative to the extrusion line width.
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Small-Scale Print Quality Score
Where:
The score gives more weight to layer height because it has a strong effect on visible stepping and vertical surface detail. Feature width contributes the remaining portion of the score.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| printQualityScore - Small-scale print quality score | A rounded setting-based score from 0 to 100 for small-model detail suitability. | percent |
| verticalDetailScore - Vertical detail score | A score based on how the selected layer height compares with the fine-detail layer-height target. | percent |
| horizontalDetailScore - Horizontal detail score | A score based on whether the smallest intended feature is at least one selected line width wide. | percent |
| layerHeight - Layer height | The height of each printed layer selected in the slicer. | mm |
| recommendedLayerHeight - Recommended detail layer height | A fine-detail starting target calculated as one-quarter of the nozzle diameter. | mm |
| nozzleDiameter - Nozzle diameter | The diameter of the installed round nozzle opening. | mm |
| smallestFeature - Smallest intended feature | The narrowest wall, raised detail, gap, or other feature the model needs to retain. | mm |
| lineWidth - Line width | The planned extrusion width for walls and small features. | mm |
| modelHeight - Model height | The finished height of the printed model. | mm |
| estimatedLayerCount - Estimated layer count | The model height divided by layer height and rounded up to a full layer. | layers |
Step-by-Step Calculation
Calculate the fine-detail layer-height target
The calculator uses 25% of the nozzle diameter as a fine-detail starting point. A smaller nozzle therefore produces a lower target layer height.
recommendedLayerHeight = nozzleDiameter * 0.25
Estimate the number of layers
Divide the model height by the selected layer height, then round up because a print cannot use a fraction of a layer.
estimatedLayerCount = ceil(modelHeight / layerHeight)
Find the feature-to-line ratio
This shows how many extrusion-line widths fit across the smallest intended feature. A ratio of 1 means the feature is one line wide.
featureToLineRatio = smallestFeature / lineWidth
Score vertical detail
Layer heights at or below the fine-detail target receive 100. As layer height rises above the target, the score falls.
verticalDetailScore = min(100, max(0, 100 - max(0, (layerHeight / recommendedLayerHeight - 1) * 100)))
Score horizontal detail
A smallest feature equal to or wider than one line width receives 100. Narrower features receive a proportionally lower score.
horizontalDetailScore = min(100, smallestFeature / lineWidth * 100)
Combine the two detail scores
The final score uses a 60% weight for vertical layer detail and a 40% weight for horizontal feature-width suitability.
printQualityScore = round(verticalDetailScore * 0.6 + horizontalDetailScore * 0.4)
Worked example: 30 mm miniature with a 0.4 mm nozzle
Fine-detail layer-height target
0.40 × 0.25
0.10 mm
Estimated layer count
ceil(30 / 0.12)
250 layers
Feature-to-line ratio
0.50 / 0.40
1.25×
Vertical detail score
100 - ((0.12 / 0.10 - 1) × 100)
80%
Horizontal detail score
min(100, 0.50 / 0.40 × 100)
100%
Final quality score
round(80 × 0.60 + 100 × 0.40)
88%
Final Result
Estimated small-scale quality score: 88%, with a 0.10 mm fine-detail layer-height target, 250 estimated layers, and a 1.25× feature-to-line ratio.
Assumptions
- ✓The calculation is intended for FDM or FFF printing with a round nozzle.
- ✓The fine-detail layer-height target is set at 25% of the nozzle diameter.
- ✓Layer height and smallest-feature width are treated as the main setting-based indicators of detail.
- ✓A feature at least one selected line width wide is treated as fully supported by the horizontal score.
- ✓The model is assumed to be printed at the entered height without adaptive layer-height changes.
Limitations
- !The score does not predict actual surface finish, dimensional accuracy, or successful adhesion of tiny features.
- !It does not account for filament type, temperature, cooling, pressure advance, retraction, speed, or extrusion calibration.
- !Slicer behavior for thin walls, gaps, and variable line widths can differ between profiles and software.
- !Model orientation, overhangs, unsupported geometry, ringing, and nozzle condition can reduce detail beyond this estimate.
- !A score of 100 does not guarantee that every fine feature will print successfully.
Common Mistakes to Avoid
Using nozzle diameter instead of the slicer's actual line width when assessing a feature.
Assuming a lower layer height will make a feature narrower than one extrusion line print reliably.
Entering a feature size from the overall model rather than measuring the narrowest important wall, gap, or raised element.
Forgetting that model orientation changes which details are limited by layers, overhangs, or support contact.
Treating the quality score as a completed-print quality guarantee instead of a setup comparison.
Comparing layer heights without accounting for the installed nozzle diameter.
Related Formulas
Frequently Asked Questions
How is the recommended layer height calculated?
The calculator multiplies nozzle diameter by 0.25. For example, a 0.4 mm nozzle gives a 0.10 mm fine-detail starting target.
What does a 100% vertical detail score mean?
It means the chosen layer height is at or below the calculator's fine-detail target for the entered nozzle. It does not mean the print will be free from visible layer lines or defects.
How is the feature-to-line ratio calculated?
It is the smallest intended feature divided by the selected line width. A 0.5 mm feature with a 0.4 mm line width has a ratio of 1.25.
Why is vertical detail weighted more heavily than horizontal detail?
The calculator assigns 60% of the score to layer-height suitability and 40% to feature width. This is a simple planning weight, not a physical measurement of print quality.
Can the quality score be below 100 when my feature is wider than the line width?
Yes. The horizontal score can be 100 while a layer height above the fine-detail target lowers the vertical score and therefore the combined result.
Does reducing layer height increase the estimated layer count?
Yes. For a fixed model height, smaller layers require more layers, which generally increases print time.
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