Where the numbers come from
Length is mass divided by density and by the cross-section of the strand: L = m / (ρ × π × r²). With grams, g/cm³ and a radius in centimetres the result comes out in centimetres, which the calculator divides by 100. The densities are the makers' published values for each product.
Two spools of "PLA" can differ by more than 5% in density, so the same weight gives a different length. Polymaker lists 1.17 g/cm³ for PolyLite PLA and 1.23 for PolyLite PLA Pro.
| Filament | Density, g/cm³ | 1 kg at 1.75 mm | 1 kg at 2.85 mm |
|---|---|---|---|
| PolyLite PLA | 1.17 | 355 m | 134 m |
| PolyLite PLA Pro | 1.23 | 338 m | 127 m |
| Polymaker PLA-CF | 1.29 | 322 m | 122 m |
| PolyLite PETG | 1.25 | 333 m | 125 m |
| Fiberon PETG-rCF08 | 1.3 | 320 m | 121 m |
| PolyLite ABS | 1.04 | 400 m | 151 m |
| Polymaker ASA | 1.13 | 368 m | 139 m |
| Prusament ASA | 1.07 | 389 m | 146 m |
| Bambu ASA | 1.05 | 396 m | 149 m |
| PolyFlex TPU95 | 1.22 | 341 m | 128 m |
| PolyLite PC | 1.19 | 349 m | 132 m |
| PolyMide CoPA (nylon) | 1.12 | 371 m | 140 m |
| Fiberon PA6-CF20 | 1.17 | 355 m | 134 m |
| Fiberon PA12-CF10 | 1.06 | 392 m | 148 m |
For the reasoning behind the figures, see the filament types guide.
Questions
How many metres are in 1 kg of 1.75 mm PLA?
About 355 m for Polymaker PolyLite PLA at 1.17 g/cm³, and about 338 m for PolyLite PLA Pro at 1.23 g/cm³. A denser filament gives fewer metres per kilogram.
How much does a metre of 1.75 mm filament weigh?
About 2.8 g for PolyLite PLA and about 2.5 g for PolyLite ABS at 1.04 g/cm³. It is the density times the cross-section of 0.0241 cm² times 100 cm.
Why does 2.85 mm filament give fewer metres per kilogram?
The cross-section grows with the square of the diameter, so a 2.85 mm strand carries about 2.65 times as much plastic per metre as a 1.75 mm one.
