How filament weight and length are related
Filament is a long cylinder, so its weight depends on three things: the diameter, the length and the density of the plastic. The calculator uses the volume of the cylinder and the material’s density.
For 1.75 mm PLA the cross-section is 2.405 mm². One metre is 2,405 mm³, or 2.405 cm³. At 1.24 g/cm³ that weighs 2.98 g, so a 1 kg spool holds about 335 metres.
Metres per kilogram by material
Lighter plastics give you more length for the same weight. A kilogram of ABS is about 65 metres longer than a kilogram of PETG.
| Material | Density g/cm³ | m per kg (1.75) | m per kg (2.85) | g per m (1.75) |
|---|---|---|---|---|
| PLA | 1.24 | 335.3 | 126.4 | 2.98 |
| PETG | 1.27 | 327.4 | 123.4 | 3.05 |
| ABS | 1.04 | 399.8 | 150.7 | 2.50 |
| ASA | 1.07 | 388.6 | 146.5 | 2.57 |
| TPU (flexible) | 1.21 | 343.6 | 129.5 | 2.91 |
| Nylon (PA) | 1.14 | 364.7 | 137.5 | 2.74 |
| Polycarbonate (PC) | 1.20 | 346.5 | 130.6 | 2.89 |
| HIPS | 1.04 | 399.8 | 150.7 | 2.50 |
| PVA | 1.23 | 338.0 | 127.4 | 2.96 |
Densities are typical values for unfilled filament. Blends with wood, metal, glass or carbon fibre differ; check the manufacturer’s data sheet and use “Custom density”.
How to check how much filament is left
- Weigh the spool on a kitchen scale.
- Subtract the weight of the empty spool. Many brands print it on the label or their website; plastic spools typically weigh 150–250 g and cardboard spools less.
- Enter the remaining grams above to see the length left.
- Compare it with the length your slicer reports for the next print, and keep a few metres spare.
Frequently asked questions
How many metres of filament are on a 1 kg spool?
About 335 m for 1.75 mm PLA, 327 m for PETG and 400 m for ABS. For 2.85 mm filament the figures are much lower: about 126 m for PLA.
How much does 1 metre of filament weigh?
About 3 g for 1.75 mm PLA and 2.5 g for 1.75 mm ABS. For 2.85 mm PLA it is about 7.9 g per metre.
Is 2.85 mm the same as 3 mm filament?
They are sold for the same printers, but most “3 mm” filament is actually 2.85 mm. Measure with calipers if you are unsure; a small difference in diameter changes the weight per metre noticeably.
Why does my slicer show a different weight?
Slicers use the density set in the filament profile. If the profile uses the wrong material or a default density, its weight estimate will differ. Set the correct density in your slicer profile.
Does colour change the density?
Slightly. Pigments and additives change density a little, and silk or matte blends can differ more. For exact figures, weigh a measured length of your own filament.
Last reviewed October 2026. See how we calculate.