STL Volume Calculator
Volume Before You've Sliced Anything
Slicers report volume once a model is loaded and sliced, but there are plenty of moments — quoting a job, sanity-checking a slicer's number, or estimating material for a model you haven't built yet — where you need a volume figure from basic dimensions alone. This calculator covers the shapes that come up most often in practice: rectangular blocks, cylinders, spheres, and a rough bounding-box estimate for organic or irregular geometry.
The Formulas
Cylinder: Volume = π × (Diameter / 2)² × Height
Sphere: Volume = (4/3) × π × (Diameter / 2)³
Bounding Box Estimate: Volume = Length × Width × Height × Fill Factor%
The bounding-box estimate is a rough approximation for irregular models — it multiplies the volume of the smallest enclosing box by an estimated fill factor representing how much of that box the actual geometry occupies.
Where This Calculation Matters
- Pre-slicing material estimates — getting a ballpark filament or resin requirement before a model is finalized or sliced.
- Quoting jobs from a customer's dimensions — a customer often supplies bounding dimensions rather than a ready STL file.
- Validating slicer output — a basic shape calculation is a quick sanity check against a slicer's reported volume.
- Comparing design variants — swapping a solid cylinder for a shape with a lower fill factor shows the material impact before committing to a design.
Worked Examples
| Shape | Dimensions | Volume |
|---|---|---|
| Box | 40 × 30 × 20 mm | 24.000 cm³ |
| Cylinder | 20mm diameter × 50mm height | 15.708 cm³ |
| Sphere | 30mm diameter | 14.137 cm³ |
| Bounding box estimate | 100 × 80 × 60 mm, 35% fill | 168.000 cm³ (of 480.000 cm³ full box) |
How to Use This Calculator
- Select the shape that best matches your model: Box, Cylinder, Sphere, or Bounding Box Estimate.
- For Box, enter length, width, and height in millimeters.
- For Cylinder, enter diameter and height. For Sphere, enter diameter only.
- For Bounding Box Estimate, enter the bounding dimensions plus an estimated fill percentage for how much of that box the model actually occupies.
- Select Calculate to get the volume in cm³.
Related Calculations
Feed the resulting volume into the Print Time Estimator or the Resin Volume Calculator for a full cost and time picture.