3D Filament Length to Weight Calculator
Enter the filament length your slicer reports and select your material and diameter. The calculator returns the weight in grams so you can check whether your spool has enough left before you start a print. Works for PLA, PETG, ABS, TPU, ASA, Nylon and carbon fibre blends.
Last updated: May 2026
How the calculation works
The calculator uses the cross-sectional area of the filament strand, the length, and the material density to compute the weight. The formula is: weight (g) = length (m) x 1000 x pi x (diameter/2)2 x density (g/cm3) / 1000. For example, 10 m of 1.75 mm PLA (density 1.24 g/cm3) weighs approximately 29.7 g. A full 1 kg spool of 1.75 mm PLA contains roughly 336 m of filament.
Material densities reference
| Material | Density (g/cm3) | Typical use |
|---|---|---|
| PLA / PLA+ | 1.24 | General purpose, easy printing |
| PETG | 1.27 | Functional parts, food-safe |
| ABS | 1.04 | Heat-resistant, automotive |
| TPU | 1.21 | Flexible parts, gaskets |
| ASA | 1.07 | UV-resistant outdoor parts |
| Nylon PA12 | 1.01 | Strong, wear-resistant |
| PLA / PETG Carbon Fibre | 1.30 | Stiff, lightweight |
Typical spool lengths
| Spool weight | PLA 1.75 mm | PETG 1.75 mm | ABS 1.75 mm |
|---|---|---|---|
| 250 g | ~84 m | ~82 m | ~100 m |
| 500 g | ~168 m | ~164 m | ~200 m |
| 1 kg | ~336 m | ~328 m | ~400 m |
Frequently Asked Questions
Why convert filament length to weight?
Slicers estimate filament use in grams, but you need to know if the length on your spool is sufficient. Weight is easy to measure with a scale, but doesn't tell you how many meters you have. This converter bridges that gap so you can check before starting a long print.
How accurate is this calculation?
The calculation assumes uniform filament diameter and consistent material density. Real-world accuracy is within 5–10% for standard materials. Variations in spool weight, filament wear, and material batches affect the result. Use it as a planning estimate, not a guarantee.
Does this work differently for different materials?
Yes. Each material has different density: PLA is 1.24 g/cm³, PETG is 1.27 g/cm³, and ABS is lighter at 1.04 g/cm³. The calculator accounts for this automatically when you select the material type. Carbon fibre blends are denser at 1.30 g/cm³.
When should I use this?
Before starting a print job that uses more filament than remains on the spool. Weigh your partial spool, enter the weight here, and know instantly whether you have enough length. Prevents failed prints and wasted time.