3D Printing Calculators
Filament Length to Weight Converter
https://www.3dsizing.com/calculators/filament-length-weight/
Estimate only — not firmware, a slicer profile or a shop quote. Confirm on a test print.
Filament Length to Weight Converter
Spools are sold by mass. Slicers and remaining-filament displays often talk in metres. This converter uses the cylinder volume of the filament and a typical density for the polymer.
Inputs
Results
- Mass
- 29.83g
- Grams per metre
- 2.983g/m
- Metres per kilogram
- 335.3m/kg
How far a 1 kg spool theoretically goes at this diameter.
Recommended gear
PLA 1.75 mm 1 kg
A kilogram of 1.75 mm PLA is typically a little over 300 m, not a kilometre.
Typical range: $15–$30
PETG 1.75 mm 1 kg
PETG is denser than PLA, so the same remaining metres weigh more.
Typical range: $18–$35
Digital caliper
Confirm the filament is actually 1.75 mm before you trust a length-to-mass conversion.
Typical range: $15–$40
Calculation method
Treat filament as a cylinder. Volume in mm³ is π r² L with r = diameter/2 in millimetres and L in millimetres (metres × 1000). Divide by 1000 for cm³, then multiply by density in g/cm³. Default densities: PLA 1.24, PETG 1.27, ABS 1.04, TPU 1.21, nylon 1.14, ASA 1.07. Length input is metres (canonical); the unit toggle shows feet.
Exact formula
Volume cm³ = π × (d_mm/2)² × (L_m × 1000) / 1000. Mass g = volume × density g/cm³. Grams per metre = mass / length. Metres per kg = 1000 / grams per metre. Limits: Densities are neat-polymer averages; foam, silk, wood-fill and wet nylon will not match.
Why slicers disagree
Slicers use a filament density setting. If yours is still 1.24 on a foaming LW-PLA, mass will be wrong even when length is right.
2.85 mm shops
Larger diameter means more mass per metre (ratio of diameters squared: (2.85/1.75)² ≈ 2.65×). Do not mix diameters in one e-step calibration.
Frequently asked questions
How much 1.75 mm PLA is in a 1 kg spool?
About 330 m at 1.24 g/cm³. The converter’s metres-per-kilogram output is the same idea for any polymer and diameter.
Is 2.85 mm the same as 3 mm?
Marketing says 3 mm; the actual diameter is usually 2.85 mm. Use 2.85 here. A true 3.00 mm strand is heavier for the same length.
Why does ABS weigh less than PLA for the same length?
ABS is less dense (~1.04 vs 1.24 g/cm³), so the same cylinder of plastic has less mass.
Can I convert grams back to metres?
Divide 1000 g by grams per metre, or invert metres per kilogram. Same density assumption.
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