Infill Calculator

3D print infill percentage determines the internal density of a printed part — 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 good pattern choice

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.