3D Printing Quality Formula
Learn how the commercial 3D printing calculator estimates quality score, material use, print time and direct unit cost.
This calculator provides a comparative production-planning estimate for an FDM-style printed part. It combines infill, support waste, material density, nozzle settings, print speed and operating rates to help compare possible production settings before using a detailed slicer estimate or test print.
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Estimated Direct Unit Cost
Where:
The direct cost per part is the estimated material consumed, plus machine run time at the hourly machine rate, plus setup and finishing labor.
Variables Explained
| Variable | What It Means | Unit |
|---|---|---|
| materialCost - Material cost | Estimated cost of material consumed, including the support and waste allowance. | currency |
| machineCost - Machine cost | Estimated machine run time multiplied by the machine hourly rate. | currency |
| laborCost - Labor cost | Setup and finishing labor multiplied by the labor hourly rate. | currency |
| modelVolume - Model volume | Finished part volume from CAD software or a slicer. | cm³ |
| infillPercent - Infill | Selected internal infill percentage. | percent |
| supportWastePercent - Support and waste allowance | Allowance for supports, brims, purge material and routine waste. | percent |
| nozzleDiameter - Nozzle diameter | Diameter of the fitted nozzle. | mm |
| layerHeight - Layer height | Height of each deposited layer. | mm |
| printSpeed - Print speed | Planned average printing speed, excluding travel speed. | mm/s |
| materialDensity - Material density | Density of the selected printing material. | g/cm³ |
| machineRate - Machine hourly rate | Operating cost assigned to each machine hour. | currency |
| setupMinutes - Setup and finishing time | Preparation, removal, basic cleanup and inspection time. | minutes |
| laborRate - Labor hourly rate | Labor cost assigned to each hour of setup and finishing. | currency |
Step-by-Step Calculation
Estimate the filled portion of the part
The selected infill is increased by 20 percentage points to allow for perimeters and top and bottom layers, with the result capped at a fully solid part.
materialFillRatio = min(1, infillPercent / 100 + 0.2)
Add support and production waste
The effective volume includes the estimated filled part plus supports, brims, purge material and routine waste.
effectiveMaterialVolume = modelVolume * materialFillRatio * (1 + supportWastePercent / 100)
Convert volume to material weight and cost
Effective volume is converted to grams using material density, then multiplied by the price per kilogram.
materialWeight = effectiveMaterialVolume * materialDensity; materialCost = materialWeight / 1000 * materialPrice
Estimate machine print time
The estimate uses a 75% effective-flow factor to allow generally for non-print movement, acceleration and production variation.
volumetricPrintRate = nozzleDiameter * layerHeight * printSpeed * 0.75; printTimeHours = effectiveMaterialVolume * 1000 / volumetricPrintRate / 3600
Calculate machine and labor cost
Machine runtime and setup labor are each priced using their entered hourly rates.
machineCost = printTimeHours * machineRate; laborCost = setupMinutes / 60 * laborRate
Calculate the comparative quality score
Finer layers relative to the nozzle, lower print speed and better expected dimensional accuracy increase this comparative 0–100 score.
qualityScore = max(0, min(100, 100 - 45 * (layerHeight / nozzleDiameter) - 20 * (printSpeed / 100) - 20 * (printerAccuracy / 0.1)))
Example: 100 cm³ PLA production part
Material fill ratio
min(1, 20 / 100 + 0.2)
0.40
Effective material volume
100 * 0.40 * (1 + 10 / 100)
44.0 cm³
Material weight and cost
44.0 * 1.24; 54.56 / 1000 * 25
54.6 g and $1.36
Volumetric rate and print time
0.4 * 0.2 * 50 * 0.75; 44000 / 3 / 3600
3.0 mm³/s and 4.1 hours
Machine and labor cost
4.074 * 8; 20 / 60 * 25
$32.59 and $8.33
Quality score
100 - 45 * (0.2 / 0.4) - 20 * (50 / 100) - 20 * (0.05 / 0.1)
57.5, or about 58/100
Final Result
Estimated direct unit cost: $42.29 per part; estimated print time: 4.1 hours; estimated material use: 54.6 g; estimated quality score: 58/100.
Assumptions
- ✓Model volume represents the finished part volume supplied by CAD software or a slicer.
- ✓A 20% volume allowance reasonably represents shells, perimeters and top and bottom layers for early-stage estimating.
- ✓The 75% effective-flow factor is suitable only as a general planning allowance.
- ✓The entered machine rate represents the operating costs the business chooses to allocate per machine hour.
- ✓The quality score is intended for comparing settings, not specifying a tolerance or surface-finish requirement.
Limitations
- !A slicer can produce a different time estimate because it models toolpaths, travel moves, acceleration, cooling, retractions and geometry.
- !Complex geometry, thin walls, bridges and small features can materially change printing behavior and material use.
- !Supports and waste can vary substantially with orientation, support strategy, material changes and the printer workflow.
- !Direct unit cost excludes profit, packaging, shipping, taxes, detailed inspection and major post-processing.
- !The score does not measure strength, anisotropy, warping, appearance, fit or material-specific surface behavior.
Common Mistakes to Avoid
Entering the outer bounding-box volume instead of the actual finished model volume.
Using travel speed rather than planned average print speed.
Treating infill percentage as the entire material fill ratio and overlooking shell material.
Leaving support and waste at zero for a part that needs supports, a brim or purge material.
Comparing quality scores between printers without updating the dimensional accuracy input.
Using direct cost as a final customer price without adding other business costs and margin.
Related Formulas
Frequently Asked Questions
How is the 3D printing quality score calculated?
It starts at 100 and applies reductions for a larger layer-height-to-nozzle ratio, higher print speed and lower expected dimensional accuracy. The final result is capped between 0 and 100.
Why does a smaller layer height improve the quality score?
Smaller layers generally reduce visible stepping on curved and angled surfaces. They also usually increase the number of layers and machine time.
Does infill change the quality score?
No. In this calculator, infill affects estimated material use and print time, but not the comparative surface-and-accuracy score.
What is the material fill ratio formula?
The formula is min(1, infillPercent / 100 + 0.2). It adds a 20% allowance for shells and caps the estimated filled volume at 100%.
Why can this print-time estimate differ from a slicer?
This formula uses an average volumetric rate. A slicer uses the actual geometry and printer settings, including travel, acceleration, cooling, retractions and feature-specific speeds.
Is the estimated direct unit cost a quote?
No. It is an internal planning estimate for material, machine time and entered setup labor. Validate it against a representative print and add other applicable costs separately.
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