How the conversion works
Filament is a long cylinder, so its weight is just volume × density:
grams per meter = density (g/cm³) × π × (diameter in cm ÷ 2)² × 100
For 1.75 mm PLA (density about 1.24 g/cm³) that is roughly 2.98 g per meter, or about 335 meters in a 1 kg spool.
Typical densities
Densities vary between brands and additives (carbon fiber, glitter, wood fill), so treat these as typical values. For the most accurate result, use the density printed on your spool or data sheet with the "Custom density" option.
- PLA ≈ 1.24 g/cm³
- PETG ≈ 1.27 g/cm³
- ABS ≈ 1.04 g/cm³ and ASA ≈ 1.07 g/cm³ (lighter, so more meters per kg)
- TPU ≈ 1.21 g/cm³
- Nylon ≈ 1.14 g/cm³, polycarbonate ≈ 1.20 g/cm³
Why it matters
Slicers report filament use in meters or grams depending on settings, and some only give one. Converting lets you check whether a long print will fit on what's left on a spool, compare spool prices across materials, and set the right density in your slicer so its weight and cost estimates are accurate.
Frequently asked questions
How many meters are in a 1 kg spool of PLA?
About 335 meters for 1.75 mm PLA, and about 125 meters for 2.85 mm PLA.
Why does ABS give more meters per kg than PLA?
ABS is less dense (about 1.04 vs 1.24 g/cm³), so the same weight takes up more volume and therefore more length.
Is 3 mm filament the same as 2.85 mm?
Almost all "3 mm" filament sold today is actually 2.85 mm. Use 3.00 only if your filament really measures 3 mm.