Filament Length Calculator
Convert 3D printer filament weight to length from diameter and material density. PLA, PETG, ABS, TPU — free and instant.
2 lb of 1.24 filament at 1.75 is about 304.2 m (731.6 cm³ of plastic).
How it works
Convert filament weight to length. Enter how much filament you have (or need), pick the diameter and material, and we compute the volume from the material's density, then divide by the cross-section area of the filament strand to get its length.
- Volume (cm³) = weight ÷ density
- Cross-section area = π/4 × diameter²
- Typical: 1 kg of 1.75 mm PLA ≈ 335 m
Enter a filament weight, diameter and material for plastic volume and length. It works in both directions in practice: convert a spool weight to length to see what you have, or convert a slicer's reported length back to grams to see what a job will consume. Note that spool weights are nominal — a 1 kg spool commonly holds a little more or less, and cheaper filament varies more in diameter, which affects both length and print quality. If a job is close to the limit, assume you have slightly less than the arithmetic suggests and keep a fresh spool ready rather than discovering the shortfall at 90 percent.
Frequently asked questions
How many metres in a 1 kg spool?
About 335 m for 1.75 mm PLA. The conversion runs through volume: 1 kg of PLA at 1.24 g/cm³ is 806 cm³, divided by the strand's cross-section of 0.024 cm². A half spool of PETG gives about 164 m, and 750 g of 2.85 mm ABS only about 113 m — thicker filament is much shorter for the same weight.
Why does material change the length?
Because density differs. ABS at 1.04 g/cm³ is lighter than PETG at 1.27, so a kilogram of ABS occupies more volume and therefore runs longer. The spread across common materials is roughly 20 percent, which matters when you are checking whether the remnant on a spool will finish a job.
How do I tell how much is left on a partial spool?
Weigh it and subtract the empty spool weight, which is usually printed on the spool or listed by the manufacturer — typically 150 to 250 g. Convert the remaining filament weight here, then compare against the length your slicer reports for the job. Weighing is far more reliable than judging by the visible diameter of the remaining coil.
Examples & notes
- Full 2.2 lb PLA spool
- Half spool of PETG
- 2.85 mm ABS
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