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Filament Weight to Length Calculator

A filament weight to length calculator divides mass by density to get volume, then divides by the circular cross-section of 1.75 mm or 2.85 mm filament. PLA at 1.24 g/cm³ gives about 335 m in a 1 kg spool of 1.75 mm.

Quick Summary & Direct Answer
Making

How long is 1 kg of PLA filament?

One kilogram of 1.75 mm PLA at 1.24 g/cm³ is about 335 metres. PETG at 1.27 g/cm³ is a little shorter. ABS at 1.04 g/cm³ is longer. Diameter is squared in the area, so 2.85 mm filament is much shorter per kilogram.

Key Takeaways

  • Length in metres = (grams / density) / (π r²) with r in centimetres, then / 100.
  • 1.75 mm and 2.85 mm are the usual diameters; 3.00 mm is treated as 2.85 mm in some shops.
  • Spool remaining uses the same density as the full spool.
  • Foamed or carbon-filled filament can miss these densities.

1,000 g → length

335.3 m

335 m → mass1,000 g
Remaining83.8 m (25%)
Full spool length335.3 m

Results can be wrong. This calculator is unofficial. Figures can be incomplete, rounded, or not updated. Use them at your own risk and check a tape, datasheet, ball band, or official chart before cutting, mixing, buying, or publishing. Densities are published typical values. Foamed, carbon, or wood-fill spools, and ±0.05 mm diameter, change length. Limits of liability are in the terms of service.

Frequently asked questions

About 335 m at 1.75 mm and 1.24 g/cm³. 2.85 mm PLA is about 126 m per kilogram.

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Publisher notes · reviewed 29 October 2026

Filament is a cylinder of known density

Volume is mass / density. Cross-section is π r² with r = diameter/20 centimetres. Length in metres is volume / area / 100. PLA 1.24 g/cm³ at 1.75 mm is about 335 m per kilogram.

Spool cardboard

Weigh filament only. The remaining-grams field is leftover plastic, not the boxed spool mass.

Worked examples

  • 1 kg PLA 1.75 mm

    About 335 m. The same mass at 2.85 mm is about 126 m.

Limits of this page

  • Foamed, wood, and carbon filaments can miss the listed density.
  • Diameter tolerance ±0.05 mm changes length.

Sources