Infill Calculator

3D print infill percentage determines the internal density of a printed part, meaning the lattice structure inside the solid outer walls. Infill directly controls print strength, weight, material usage, and print time.

Material volume formula: Internal Volume = Part Volume × (1 − Shell Fraction) × (Infill % ÷ 100)

Total material used: Total Volume = Shell Volume + Internal Volume Filament Length = Total Volume ÷ (π × (Filament Diameter ÷ 2)²)

Where:

• Part Volume: total geometric volume of the model in mm³
• Shell Fraction: proportion occupied by perimeter walls; 3 walls × 0.4mm each = 1.2mm, typically 10–30% of volume depending on part size
• Infill %: percentage of interior space filled; 0% is hollow (shell only), 100% is completely solid
• Filament Diameter: 1.75mm or 2.85mm; the formula converts volume to filament length for cost estimation

Infill patterns and their strength characteristics:

• Grid/Rectilinear (0°/90°): Fast, decent strength in XY, weak in Z
• Gyroid: Excellent isotropic strength in all directions, good for flexible parts
• Honeycomb: Strong, moderate speed, visually appealing
• Lightning: Fastest, minimal material, supports top surfaces only, not structural
• Cubic/3D Honeycomb: Strong in all 3 axes; recommended for structural parts

Reference: infill percentage guidelines:

• 0–5%: Decorative only (vases, figurines, no load)
• 10–20%: Light-duty parts, enclosures, prototypes
• 20–40%: General purpose, most everyday prints
• 40–60%: Mechanical parts with moderate stress
• 60–80%: High-stress functional parts
• 80–100%: Maximum strength, rarely needed above 60% with a good pattern choice

Those bands describe infill on its own. The strength rating in the result panel deliberately counts walls too, scoring each wall as worth about 10 points of infill, because perimeters carry far more load than the lattice inside them does. So a 30% part with three walls rates higher there than the 20–40% row here suggests, and that is the honest answer: adding a fourth wall does more for strength than pushing infill from 30% to 50%, and costs less material.

Worked example: Part volume: 45,000 mm³. Gyroid infill at 30%. 3 perimeters at 0.4mm = shell ~24% of volume (the calculator uses 8% per wall).

• Shell volume = 45,000 × 0.24 = 10,800 mm³
• Internal volume available = 45,000 − 10,800 = 34,200 mm³
• Infill material = 34,200 × 0.30 = 10,260 mm³
• Total material = 10,800 + 10,260 = 21,060 mm³

Increasing infill from 30% to 60% adds only 10,260 mm³ more material (≈ 13g more PLA at 1.24 g/cm³) but roughly doubles the part’s compression strength.