🖨️ 3D printing
Filament Converter
Convert filament between grams, kilograms, ounces, metres, feet and cubic centimetres. Set your filament diameter and material, enter a value and press Convert.
About the filament converter
A spool is sold by weight but a print is sliced by length, so every maker ends up converting between the two. The missing link is the filament's cross-section: a 1.75 mm strand has an area of 2.405 mm², and one metre of it occupies 2.405 cm³. Multiply by the material density and you have grams per metre.
That is why PLA gives about 335 m on a 1 kg spool while ABS gives around 400 m — ABS is lighter, so the same weight buys more length.
Filament weight and length by material
| Material | Density | g per m at 1.75 mm | g per m at 2.85 mm | Metres per 1 kg at 1.75 mm |
|---|---|---|---|---|
| PLA | 1.24 | 2.98 | 7.91 | 335 |
| PETG | 1.27 | 3.05 | 8.10 | 328 |
| ABS | 1.04 | 2.50 | 6.64 | 400 |
| ASA | 1.05 | 2.53 | 6.70 | 396 |
| TPU flexible | 1.21 | 2.91 | 7.72 | 344 |
| Nylon (PA) | 1.14 | 2.74 | 7.27 | 365 |
| Polycarbonate | 1.20 | 2.89 | 7.66 | 347 |
| Wood-fill | 1.28 | 3.08 | 8.17 | 325 |
| Carbon-fibre blend | 1.30 | 3.13 | 8.29 | 320 |
The maths
- Cross-section: A = π × d² ÷ 4. For 1.75 mm that is 2.4053 mm².
- Millimetres of filament: L = volume (mm³) ÷ A.
- Grams: mass = volume (cm³) × density.
- Grams per metre: A × density ÷ 1,000 — because 1,000 mm of filament is 1,000 × A mm³, or A cm³.
Worked examples
- 1 metre of 1.75 mm PLA weighs 2.98 g, so a 100 m print uses about 298 g.
- A slicer reporting 84 g of 1.75 mm PETG is 84 ÷ 3.05 = 27.5 m of filament.
- A 2.85 mm spool of ABS holds about 151 m per kilogram, less than half the length of the 1.75 mm equivalent.
- A part with a volume of 250 cm³ printed solid in PLA needs 250 × 1.24 = 310 g — before infill and supports are considered.
Frequently asked questions
About 335 m of 1.75 mm filament at 1.24 g/cm³. Makers sometimes include the spool's own weight, so a "1 kg spool" can hold slightly less.
Yes. Mass depends on the square of the diameter, so a strand averaging 1.80 mm instead of 1.75 mm weighs about 6% more per metre and can over-extrude if the slicer does not know.
To turn the model volume into grams of material, which is what flow calibration, cost estimates and filament run-out warnings are built on.
The mass and volume conversions work for any material, but the length figures assume a round strand, so they do not apply to pellets or resin vats.
Common mistakes to avoid
- Using a spool's gross weight. Filament tracking software works from net weight.
- Assuming 1 m of filament is roughly 1 g. It is closer to 3 g of PLA.
- Ignoring infill and supports when estimating a print. Slicer estimates already account for them — hand calculations do not.
- Mixing 2.85 mm and 3 mm. They are close but the area differs by 11%.