How we worked it out
Updated as you change the numbers.
- Cross-section = π × (1.75 mm ÷ 2)² = 2.405 mm² = 0.02405 cm².
- Weight per meter = 1.24 g/cm³ × 0.02405 cm² × 100 cm = 2.983 g.
- Length = 50 g ÷ 2.983 g/m = 16.76 m.
Method and assumptions
Filament is a long cylinder, so its weight per meter is density × cross-section area × length. Densities are typical values from manufacturers’ data sheets; blends, fills (wood, carbon fiber, glow) and brands differ slightly, so use the figure on your spool if it gives one.
Tips
- Slicers estimate filament from the toolpath; real use adds a little for purge lines, skirts and failed starts.
- Spool weight on the label is the filament only; the empty spool weighs 150 to 250 g more.
Questions
How many meters are on a 1 kg spool of PLA?
About 335 m of 1.75 mm PLA, or about 126 m of 2.85 mm.
Sources
Method and figures checked on . Every worked answer on this page is covered by an automated test. Found a mistake? Tell us.