Filament Length Calculator — Metres per Spool
Calculate the total length of filament on a spool from its weight, diameter and material density.
Net filament weight (not including spool)
Select filament diameter or choose Custom
Select the material type
How We Calculate This
Formula
The calculator uses the relationship between mass, density, and volume:
- Volume = Weight / Density
- Cross-sectional area = pi x (diameter/2)^2
- Length = Volume / Cross-sectional area
The weight is divided by the material density to get total volume in cm3, then divided by the filament cross-sectional area to get length in centimetres, which is converted to metres.
Frequently Asked Questions
Related Calculators
Filament Weight Calculator
Estimate how much filament a print will use by weight from model volume.
Filament Cost Calculator
Work out the material cost of a print based on filament weight and spool price.
Spool Life Calculator
Estimate how many prints you can get from one spool of filament.
Filament Diameter Calculator
Calculate cross-sectional area and volume per metre for any filament diameter.
Filament Density Calculator
Look up or calculate filament density for common 3D printing materials.
Last updated: February 2026
All calculations are estimates. Always verify settings with test prints before committing to final prints.