Infill Weight Calculator — Material Weight & Filament Length by Infill

Infill percentage controls the density of the internal structure. At 0% infill, the part is hollow (only shells). At 100%, it is solid throughout. The relationship is approximately linear for the interior volume: doubling infill roughly doubles the infill material used, while the shell weight stays constant. For most functional parts, 15–25% infill provides adequate strength at a significant material saving.

Shell weight is the material used for the outer perimeter walls and top/bottom solid layers — this is always fully solid regardless of infill setting. Infill weight is the material used inside the part at your chosen infill density. For small parts with thin walls, the shell can account for 50–80% of total weight.

Enter the bounding-box length, width and height (X, Y, Z) of the part in millimetres. Every slicer shows these: in PrusaSlicer and Bambu Studio the object size appears in the right-hand object/manipulation panel; in Cura it is in the Scale tool and the object list. You can also read them straight from your CAD software (Fusion 360: Inspect > Measure or the bounding-box dimensions; Blender: the Item panel, N key). Using real dimensions — rather than a single volume figure — is what lets the calculator separate the solid shell from the infilled interior correctly.

The print time estimate is a rough guide based on the volumetric-flow model: time ≈ extruded volume ÷ (print speed × layer height × line width), with a 0.5 duty factor to allow for travel moves, acceleration, retraction and cooling. Slicer software is far more accurate because it simulates every move, per-feature speeds, fan delays and layer transitions, so use your slicer's figure for planning. This calculator is best for quick comparisons between different infill settings on the same part.

General decorative prints: 10–15%. Standard functional parts: 20–30%. High-strength mechanical parts: 40–60%. Parts under significant load or impact: 60–80%. Solid (100%) is rarely needed — a well-designed part at 40% infill with 3–4 perimeters is usually stronger than 100% infill with fewer walls, because perimeter walls contribute more to tensile strength.