How to use it
- Drag an
.stlonto the drop zone above (3MF, OBJ, STEP and other formats work too), or click Choose 3D file. - The analysis panel opens with the model's volume and its estimated weight. Switch the material between PLA, PETG, ABS and resin to compare.
- Check the watertightness line: the weight is only reliable for a closed mesh.
The figure is for a solid part at 100 % infill. For other materials, or to estimate a real FDM print, use the table and formula below with the volume and surface area the panel shows.
Density of common filaments and resin
| Material | Density (g/cm³) | 1 cm³ weighs |
|---|---|---|
| PLA | 1.24 | 1.24 g |
| PETG | 1.27 | 1.27 g |
| ABS | 1.04 | 1.04 g |
| ASA | 1.07 | 1.07 g |
| TPU (95A) | 1.21 | 1.21 g |
| Nylon (PA6/PA66) | 1.14 | 1.14 g |
| Polycarbonate | 1.20 | 1.20 g |
| Standard resin | 1.15 | 1.15 g |
These are typical values for unfilled materials. Filled filaments differ a lot — metal-filled PLA can be two to three times heavier — so for anything you are quoting, use the figure on the spool's datasheet. The density reference lists more materials and converts spool weight to metres.
From solid weight to a realistic FDM estimate
A slicer does not fill the model solid. It prints a shell — a few perimeter walls plus solid top and bottom layers — and fills the inside with sparse infill. A useful approximation:
shell volume (cm³) ≈ surface area (cm²) × shell thickness (cm)
interior volume (cm³) = volume − shell volume
printed volume (cm³) ≈ shell volume + interior volume × infill
weight (g) ≈ printed volume × density
With two walls from a 0.4 mm nozzle, a shell thickness of about 0.08–0.09 cm (0.8–0.9 mm) is a fair assumption. The analysis panel shows both the volume in cm³ and the surface area in cm².
Worked example — a 20 mm cube in PLA at 15 % infill:
- volume = 8.00 cm³, surface area = 24.00 cm²
- shell ≈ 24 × 0.08 = 1.92 cm³
- interior = 8.00 − 1.92 = 6.08 cm³, × 0.15 = 0.91 cm³
- printed ≈ 1.92 + 0.91 = 2.83 cm³ → ≈ 3.5 g of PLA
The solid figure would be 9.9 g. For thin-walled or small parts the shell dominates, and the estimate gets close to the solid weight; for big, chunky parts infill dominates and the gap widens. Supports and brims come on top.
Resin prints
Resin parts are usually printed solid or hollowed, not with sparse infill, so the solid weight is a good estimate for a solid print. Resin is sold by volume as well as by weight: 1 cm³ of model is about 1 ml of resin. Add supports and the film left on the vat and build plate.
Estimating cost
cost = grams × spool price ÷ spool weight in grams
A 35 g part from a 1 kg spool that cost 20 (in any currency) uses about 0.70 of material. Electricity, wear and failed prints are extra.
Common reasons the number looks wrong
- Wrong units. If a part reads tiny, the STL was probably exported in inches or metres; see STL units.
- Open mesh. Holes make volume — and weight — unreliable.
- Overlapping bodies. Intersecting shells are counted twice.
- Hollow by design. A model that is already a thin shell (a vase-mode print, for example) weighs what its walls weigh.
On your phone
The calculator works in a phone browser too. The Mes3D app for iPhone, iPad and Android adds a wall-thickness view and problem-area highlighting, so you can see why a part is heavier or weaker than expected, plus cross-sections and resizing to exact dimensions.