What is the Filament Usage Calculator?
This tool estimates how much 3D printing filament a job consumes — by weight, volume, and cost — from the filament length reported by your slicer. Slicers like Cura and PrusaSlicer report length in meters but you often want grams (to track spool usage) or cost (to price a print). This calculator converts length into mass using the filament cross-section and material density.
How to use it
Enter the filament length used (in meters), pick your filament diameter (\(1.75\,\text{mm}\) is most common), choose the material so the right density is applied, and optionally enter your spool price per kilogram and the spool net weight. The result shows mass in grams, extruded volume in cm³, estimated cost, and what fraction of a full spool the print uses.
The formula
Filament is a solid cylinder, so its volume is the circle area times the length. Mass is volume times density:
$$m = \pi \left(\frac{d}{2}\right)^2 L \times \rho$$where \(d\) = filament diameter, \(L\) = length used, and \(\rho\) = material density. Diameter (mm) and length (m) are both converted to centimeters so the volume comes out in cm³ and mass in grams. Cost is then:
$$C = \frac{m}{1000} \times P$$with \(P\) = spool price per kg.
Worked example
Suppose a print uses \(L = 10\,\text{m}\) of \(1.75\,\text{mm}\) PLA (\(\rho = 1.24\,\text{g/cm}^3\)). The radius is \(0.0875\,\text{cm}\) and length is \(1000\,\text{cm}\):
$$V = \pi (0.0875)^2 \times 1000 = 24.05\,\text{cm}^3$$ $$m = 24.05 \times 1.24 = 29.82\,\text{g}$$At \(P = 20\) per kg, the cost is \(\frac{29.82}{1000}\times 20 = 0.60\).
FAQ
Where do I find the length used? Your slicer shows it in the print summary, usually labeled "filament used" in meters and grams.
Does this account for infill and supports? Yes — as long as you enter the total length your slicer reports, everything is included.
Which density should I pick? Use the value on your spool if listed; otherwise the presets (PLA ~1.24, ABS/PETG ~1.27, TPU ~1.08 g/cm³) are good defaults.
