What the STL Volume & Weight Calculator Does
The MeshKit STL Weight Calculator computes the geometric volume (`cm³`) of a 3D mesh from an uploaded `.stl` file (or a manual volume input) and converts that displaced volume into part weight in grams (`g`) and required filament length in meters (`m`) across ten engineering polymers (PLA, PETG, ABS, ASA, TPU, Polycarbonate, Nylon/PA, HIPS, PVA, and carbon-fiber composites).
When quoting a customer part before slicing, knowing the solid mesh volume and effective density lets you estimate polymer mass and compare material choices (for example, how much lighter a part is in ABS at `1.04 g/cm³` versus PETG at `1.27 g/cm³`).
How to Calculate STL Part Weight in 3 Steps
- Upload an `.STL` File or Enter Volume (`cm³`): Drop a binary or ASCII `.stl` file into Section A to extract exact signed tetrahedral volume (`cm³`), or type a known CAD volume into the Mesh Volume field.
- Set Effective Fill Percentage: For solid resin or 100% infill parts, keep Effective Fill at `100%`. For FDM parts with shells and sparse infill, enter the combined effective solid fraction (typically `25%–45%` for 2–3 walls and 15–20% infill).
- Choose Polymer Density & Filament Diameter: Select your material preset or enter a custom density from your manufacturer's technical datasheet, then choose `1.75 mm`, `2.85 mm`, or `3.00 mm` filament.
Worked Example: Cube Volume to Grams & Meters
For a solid `10 × 10 × 10 mm` cube (`1.000 cm³`, Golden Vector C13) or a `38.4 cm³` bracket printed at `100%` effective fill in PLA (`1.24 g/cm³`) with `1.75 mm` filament:
Part Weight = 38.4 cm³ × 1.00 × 1.24 g/cm³ = 47.616 g (47.6 g)
Grams per Meter (1.75 mm PLA) = π × (0.175 cm ÷ 2)² × 100 × 1.24 = 2.9825 g/m
Filament Length = 47.616 g ÷ 2.9825 g/m = 15.96 m (16.0 m)
Technical Limitations
Signed tetrahedral volume integration requires a reasonably closed mesh. If an `.stl` file has large missing faces or unclosed boundary holes, the signed volume integral will under- or over-estimate volume; run STL Repair Online first to seal holes before relying on volume numbers. Furthermore, in FDM printing, perimeters, top/bottom solid layers, and support structures increase total filament usage beyond the raw infill percentage alone—use the G-Code Time Estimator once sliced for exact extruder mass.
Frequently Asked Questions
Why does an ABS part weigh less than the same STL printed in PLA?
ABS has a density of `1.04 g/cm³`, whereas PLA has a density of `1.24 g/cm³` (and PETG is `1.27 g/cm³`). For the exact same STL volume and slicing settings, an ABS print weighs about 16% less in grams than PLA.
Are cm³ and mL identical for SLA resin printing?
Yes. One cubic centimeter (`1 cm³`) is exactly equal to one milliliter (`1 mL`). You can copy the `cm³` volume from this tool directly into the SLA Resin Print Cost Calculator.
How is STL volume calculated mathematically?
Every triangle in the mesh forms a signed tetrahedron with the coordinate origin `(0,0,0)` whose volume is `v0 · (v1 × v2) / 6`. Summing across all triangles cancels interior regions and yields the exact enclosed volume in `mm³` (`1,000 mm³ = 1 cm³`).
What if my STL was exported in inches instead of millimeters?
STL files store unitless numbers that slicers interpret as millimeters. If a CAD model was exported in inches, its dimensions will appear `25.4×` smaller (`25.4³ = 16,387×` smaller in volume). Re-export in millimeters or use our STEP to STL Converter with millimeter units.