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Open toolSTL Volume Calculator
Compute the exact 3D interior volume (`mm³`, `cm³`, `in³`), total surface area, bounding box dimensions, watertight half-edge manifold status, and estimated part mass (`g` / `kg`) directly from ASCII STL triangle facets.
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Enter your details
Enter the inputs, then select Calculate STL Volume & Weight.
Your result
Enter your details
Result will appear here
How Signed Tetrahedral STL Volume & Manifold Checking Work
The calculator parses every triangle (`v1, v2, v3`) from your ASCII STL text, evaluates the scalar triple product, and verifies half-edge topology.
V = |sum_{i=1..N} ((v1_i x v2_i) . v3_i) / 6|; Watertight check: every directed edge (A -> B) is paired with exactly one opposite directed edge (B -> A).
Uses the exact divergence theorem (signed tetrahedral volume from the origin) and checks directed half-edge pairing so open/non-manifold meshes trigger an explicit watertightness warning.
Common 3D Printing & Engineering Material Densities Reference Table
Standard material densities (`g/cm³`) used to convert STL mesh volume (`cm³`) into part mass (`grams`).
| Material | Category | Density (g/cm³) | Mass per 1,000 mm³ (1 cm³) Solid |
|---|---|---|---|
| PLA (Polylactic Acid) | FDM Filament | `1.24 g/cm³` | `1.24 g` |
| PETG | FDM Filament | `1.27 g/cm³` | `1.27 g` |
| ABS | FDM / Injection | `1.04 g/cm³` | `1.04 g` |
| Standard SLA / MSLA Resin | Photopolymer | `1.12 – 1.18 g/cm³` | `~1.15 g` |
| Aluminum 6061 | CNC / Die Cast | `2.70 g/cm³` | `2.70 g` |
| Stainless Steel 316L | DMLS / CNC | `7.99 g/cm³` | `7.99 g` |
How to use STL Volume Calculator step by step
Enter the values for your scenario, verify the units, and run the calculation.
Enter the inputs
Start by entering the required fields in the STL Volume Calculator form above.
Verify units and assumptions
Match each value to the unit or format shown next to the input box before running the calculation.
Run and export your result
Select Calculate STL Volume & Weight, inspect the primary metric and breakdown cards, then use Copy result or Download result.txt.
Worked examples for STL Volume Calculator
Compare baseline and alternative runs for STL Volume Calculator before exporting the result.
Baseline example
Compute signed tetrahedral volume, surface area, bounding box dimensions, watertight edge warnings, and estimated 3D printing part weight from ASCII STL mesh geometry.
Comparison scenario
V = |sum_{i=1..N} ((v1_i x v2_i) . v3_i) / 6|; Watertight check: every directed edge (A -> B) is paired with exactly one opposite directed edge (B -> A).
Boundary check before exporting
Uses the exact divergence theorem (signed tetrahedral volume from the origin) and checks directed half-edge pairing so open/non-manifold meshes trigger an explicit watertightness warning.
How to interpret the STL Volume Calculator output
Review the calculated output alongside your entered parameters and unit conventions.
Uses the exact divergence theorem (signed tetrahedral volume from the origin) and checks directed half-edge pairing so open/non-manifold meshes trigger an explicit watertightness warning.
Pre-Quoting STL Geometry Checklist
Confirm these three details before ordering material or quoting a client.
V = |sum_{i=1..N} ((v1_i x v2_i) . v3_i) / 6|; Watertight check: every directed edge (A -> B) is paired with exactly one opposite directed edge (B -> A). Uses the exact divergence theorem (signed tetrahedral volume from the origin) and checks directed half-edge pairing so open/non-manifold meshes trigger an explicit watertightness warning.
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Open toolSTL Volume Calculator: common questions
Answers about using STL Volume Calculator and understanding its results.
How is the volume of an STL triangle mesh calculated mathematically?
Using the divergence theorem, each triangle facet with vertices (v1, v2, v3) forms a signed tetrahedron with the coordinate origin (0,0,0) whose signed volume is (v1 × v2) · v3 / 6. Summing the signed volumes across all triangles of a closed, outward-oriented watertight mesh cancels out all exterior regions and yields the exact interior volume of the 3D solid, regardless of where the origin lies.
Why does a non-watertight (open) STL mesh produce an inaccurate volume?
Because the signed tetrahedral sum relies on the mesh forming a closed 2-manifold boundary. If a mesh has missing triangles (boundary holes) or flipped face normals, tetrahedra from the origin to the missing hole are not closed off, making the computed volume depend on the model's position relative to (0,0,0).
Why did my STL volume change by 1,000x or 16,387x?
STL files do not store measurement units in their header—a vertex at (10, 10, 10) could mean 10 mm or 10 inches. Converting 1 in³ to mm³ multiplies volume by 25.4³ = 16,387.064, and converting cm³ to mm³ multiplies volume by 10³ = 1,000.
How do I estimate 3D print weight from STL volume?
Multiply the mesh volume in cubic centimeters (cm³) by the filament or resin density in g/cm³ (for example, 1.24 g/cm³ for PLA, 1.04 g/cm³ for ABS, 1.27 g/cm³ for PETG) and the effective solid fraction (100% for SLA resin or solid parts; typically 25%–45% for FDM parts accounting for solid perimeters + infill).
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