Density is the bridge between geometry and cost. A mesh gives you a volume; density turns it into grams, and grams turn into money and print time.
Typical densities
| Material | Density (g/cm³) |
|---|---|
| PLA | 1.24 |
| PETG | 1.27 |
| ABS | 1.04 |
| ASA | 1.07 |
| HIPS | 1.04 |
| TPU (95A) | 1.21 |
| Nylon (PA6/PA66) | 1.14 |
| Nylon (PA12) | 1.01 |
| Polycarbonate | 1.20 |
| Polypropylene | 0.90 |
| PVA (support) | 1.23 |
| Standard resin | 1.15 |
These are typical values for unfilled materials and are accurate enough for estimating. For anything you are quoting a price on, use the figure from the spool's technical datasheet — brands differ, and additives shift the number.
Composites move it a lot more than most people expect:
- Wood-filled PLA is usually slightly lighter than plain PLA, around 1.15–1.25, and varies by fill percentage.
- Glow-in-the-dark PLA is heavier, roughly 1.25–1.30, because the phosphorescent pigment is a mineral.
- Carbon-fibre filled grades sit close to their base polymer; the fibres add stiffness far more than mass.
- Metal-filled PLA (bronze, copper, steel) commonly lands between 2.0 and 4.0 — two to three times standard PLA. A spool holds proportionally fewer metres.
- Foaming PLA is the opposite case: its effective density depends on print temperature, because the foaming agent expands the extrusion. There is no single correct number.
Volume to weight
weight (g) = volume (cm³) × density (g/cm³)
Mesh volume is usually reported in mm³, so divide by 1000 first. A 20 mm cube is 8000 mm³ = 8 cm³, which is 9.9 g in PLA or 10.2 g in PETG.
That figure assumes a completely solid part. A typical FDM print is a few perimeter walls, some solid top and bottom layers, and 10–20 % sparse infill, so actual consumption is frequently under a third of the solid number. Treat mesh weight as a ceiling and a comparison tool, not a prediction — the maths and its failure modes are covered in volume and print weight.
Spool weight to filament length
Filament is sold by mass but consumed by length. To convert, divide the volume by the filament's cross-sectional area:
length = mass / (density × area)
area(1.75 mm) = π × 1.75² / 4 ≈ 2.405 mm²
area(2.85 mm) = π × 2.85² / 4 ≈ 6.379 mm²
For a 1 kg spool of 1.75 mm filament:
| Material | Approx. length |
|---|---|
| PLA | 335 m |
| PETG | 327 m |
| ABS | 400 m |
| TPU | 344 m |
| Nylon (PA6) | 365 m |
| Polycarbonate | 346 m |
The same 1 kg of PLA in 2.85 mm gives about 126 m, since the thicker filament has 2.65 times the cross-section.
Where these numbers are used
A viewer that reports estimated print weight is doing exactly the first calculation: mesh volume in cm³ multiplied by the selected material's density, at 100 % infill. Mes3D offers PLA, PETG, ABS and resin, which covers the overwhelming majority of prints; for anything else, take the volume figure it reports and multiply by the density from the table above.