3DPrintCalcs
Filament Diameter Calculator — Cross-Section & Volume
Calculate cross-sectional area and volume per metre for any filament diameter.
Material density is used to calculate weight per metre and spool length.
How We Calculate This
Formulae
- Cross-sectional area = π × (diameter / 2)²
- Volume per metre = area (cm²) × 100 cm
- Weight per metre = volume × material density
- Length per spool = spool weight / weight per metre
Material Density
Different materials have different densities. PLA is ~1.24 g/cm³, ABS is lighter at ~1.04 g/cm³. This affects how many metres you get per spool.
Frequently Asked Questions
1.75mm is by far the most common diameter today. 2.85mm (sometimes called 3mm) is used by some Ultimaker and Lulzbot printers. 1.75mm offers more precise extrusion control.
Smaller diameter filament gives finer flow control because the extruder gear moves less volume per millimetre fed. A 1% diameter variation in 1.75mm filament causes about a 2% flow change, because volume scales with the square of diameter (area = pi x (d/2)^2). That is also why slicers apply a flow correction of (measured diameter / nominal diameter)^2.
Use digital callipers to measure in at least 5 spots along a 1m length and take the average. Good filament should be within +/- 0.02mm of nominal.
Related Calculators
Filament Length Calculator
Calculate the total length of filament on a spool from its weight and diameter.
Filament Weight Calculator
Estimate how much filament a print will use by weight from model volume.
Filament Density Calculator
Look up or calculate filament density for common 3D printing materials.
Colour Mixing Calculator
Calculate filament ratios for multi-colour or gradient prints.
Filament Storage Calculator
Calculate desiccant requirements and storage container sizes for your filament collection.
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Last updated: February 2026
All calculations are estimates. Always verify settings with test prints before committing to final prints.