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Filament Length Calculator
Convert 3D printer filament between weight in grams and length in metres. Choose the diameter and material density on your spool for a useful planning estimate.
Convert your filament
Density basis: Family preset (approximate, editable).
Estimated result
335.3 m
This is the approximate filament length for the entered weight.
What this estimate includes
The calculation treats filament as a solid cylinder. It is useful for comparing spool labels, planning stock and translating slicer estimates. Actual spool length can vary with diameter tolerance, density, additives and manufacturer specification. Use the value printed on your spool when it differs.
Reproduce an illustrative conversion
Choose 1,000 g and an illustrative density of 1.24 g/cm³. This is an editable example input, not a universal PLA value or a measured spool.
Area = π × (diameter / 2)² mm². Volume = mass / density cm³. Converting cm³ to mm³ and mm to metres cancels the factor of 1,000, so length (m) = mass / (density × area).
For 1.75 mm filament: 1,000 / (1.24 × π × 0.875²) = 335.3 m. For 2.85 mm at the same mass/density: 126.4 m. In reverse, 335.3 m at 1.75 mm is about 1,000.1 g after rounding.
The result describes solid filament. For complete job consumption, include support and purge and use the partial-spool planner.
You have a result to review. Check complete-job sufficiency
Conversion is different from partial-spool sufficiency
A known filament mass converts to approximate length using circular cross-section and density. For a remaining spool, first subtract the measured empty reel: 350 g gross - 200 g tare = 150 g. Subtracting a 20 g reserve leaves 130 g usable, enough for two 45 g copies.
Interpret the result and choose the next step
Use the exact product density when available; filled formulations and diameter variation change length. This conversion page does not know supports, purge or the whole job estimate. The partial-spool tool owns the decision about what can actually be completed from usable stock.
Check complete-job sufficiency