Filament
Filament cost calculator
How many grams is that length of filament — and how many metres are left on that part-spool? Convert length, weight and volume in either direction, per material.
The formula
A filament strand is a cylinder. Its volume is the cross-section times the length:
volume (cm³) = π × (diameter ÷ 2)² × length (mm) ÷ 1000
weight (g) = volume (cm³) × density (g/cm³)
For 1.75 mm PLA at 1.24 g/cm³, one metre weighs π × 0.875² × 1000 ÷ 1000 × 1.24 = 2.98 g. A 1 kg spool is therefore about 335 m of filament, not the 330 m the label rounds to.
Diameter is squared, so it matters more than people expect. Moving from 1.75 mm to 2.85 mm multiplies the cross-section by 2.65 — the same 1 kg spool holds 126 m instead of 335 m.
Where the density comes from
Densities are taken from manufacturer technical data sheets (ISO 1183), not from a list someone copied off a forum. Each value on this site links the sheet it came from, because pigments and additives do move the number by a few percent. Open “Sources used on this page” above to see them, or compare every material at once on the material density chart.