Filament Length Calculator
How many meters of filament is that — or how many grams is this length?
Filament
Advanced optionsDiameter and density — sensible defaults are already applied
Industry-typical value for this material — override if your filament lists its own.
Filament length
33.53 m
- Filament weight
- 100 g
- Density used
- 1.24 g/cm³
How it's calculated
Filament is essentially a long cylinder, so its weight and length are linked through its cross-sectional area, its density, and basic volume geometry:
Volume
Weight ÷ Density
Cross-section area
π × (Diameter ÷ 2)²
Length
Volume ÷ Cross-section area
Length-to-weight mode runs the same relationship in reverse. Diameter is entered in mm and converted internally; the result is shown in meters.
Assumptions
- Industry approximationMaterial density defaults to a typical published value for that plastic — actual density varies slightly by brand and color, and more significantly for TPU. Override it if your filament lists an exact figure.
- Your inputWeight/length input and filament diameter — you enter these directly.
Worked example
You have 250g of 1.75mm PLA (density 1.24 g/cm³) remaining on a spool.
Volume = 250 ÷ 1.24 = 201.6 cm³. Cross-section area = π × (0.0875 cm)² ≈ 0.02405 cm². Length = 201.6 ÷ 0.02405 ≈ 8383 cm ≈ 83.8 m.
Frequently asked questions
Why does material choice affect the length for the same weight?
Filament is sold by weight, but different plastics have different densities, so the same number of grams takes up a different volume — and therefore a different length — depending on the material. Denser materials like PETG pack more mass into the same length than lighter materials.
Which filament diameter should I use, 1.75mm or 2.85mm?
1.75mm is by far the most common size for desktop FDM printers. 2.85mm (sometimes labeled 3mm) is used on some older or industrial machines, notably Ultimaker and some Lulzbot printers. Check your printer's specifications if you're unsure.
Is the density value exact for my specific filament?
The default densities are industry-typical averages for each material and are a good estimate for most brands. Actual density can vary slightly by manufacturer and color (especially for TPU, which varies a lot by hardness). If your filament's product page or datasheet lists a density, enter it directly for a more precise result.
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