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How much filament is on a spool?
Short answer: a 1 kg spool of 1.75 mm PLA holds about 335 metres. The same weight of 2.85 mm PLA is about 126 metres. Other materials differ because of density.
Metres per spool by material
| Material | Density g/cm³ | 1 kg, 1.75 mm | 1 kg, 2.85 mm | 250 g, 1.75 mm |
|---|---|---|---|---|
| PLA | 1.24 | 335 m | 126 m | 84 m |
| PETG | 1.27 | 327 m | 123 m | 82 m |
| ABS | 1.04 | 399 m | 150 m | 100 m |
| ASA | 1.07 | 388 m | 147 m | 97 m |
| TPU | 1.21 | 343 m | 129 m | 86 m |
| Nylon | 1.14 | 364 m | 137 m | 91 m |
The maths
Filament is a cylinder. A 1.75 mm strand has a cross-section of π × 0.875² = 2.405 mm², so one metre is 2,405 mm³ = 2.405 cm³. Multiply by density for grams per metre (PLA: 2.98 g/m), then divide the spool weight by that.
metres = grams ÷ (density × π × (d/2)² ÷ 1000)
How much is left on my spool?
Weigh the spool and subtract the empty spool weight. Empty spools vary widely — roughly 120–150 g for cardboard and 180–260 g for plastic — so weigh an empty one from the same brand once and note it. Convert the remaining grams to metres with the converter below and compare with your slicer's filament estimate before a long print.
How many prints is that?
A typical small print (phone stand, figurine) uses 20–60 g, so a 1 kg spool gives roughly 15–50 prints. Drop your STL into the weight calculator for an exact number.
Recommended gear
- Digital kitchen scale (0.1 g) — Weigh spools to see what is left; 0.1 g resolution is plenty.
- PLA filament, 1 kg (1.75 mm) — The default for most prints; buy a known brand with tight diameter tolerance.
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