How strong are 3D printed parts compared to injection-moulded?

FDM printed parts typically achieve 50-80% of the strength of injection-moulded equivalents in XY, but only 20-50% in the Z direction (between layers). Higher infill, more walls, and optimal orientation can close this gap significantly.

Does infill percentage affect strength linearly?

No. Going from 10% to 20% infill roughly doubles internal strength, but the walls contribute most of the structural strength. Beyond 40% infill, strength gains diminish. More walls are often more effective than more infill.

Why is Z-axis strength so much lower?

The Z-axis (layer direction) relies on layer adhesion rather than continuous filament strands. Layer adhesion is typically 20-60% of the filament tensile strength. Increasing print temperature and reducing cooling can improve inter-layer bonding.

Which material is strongest for 3D printing?

Nylon Carbon Fibre (PA-CF) offers the highest strength-to-weight ratio among common FDM materials (~85 MPa tensile). Polycarbonate (PC) is also very strong. For easy-to-print strength, PLA has surprisingly high tensile strength at 50 MPa.

3DPrintCalcs

Material Strength Calculator — Tensile & Compressive Strength

Estimate tensile and compressive strength based on material and print orientation.

Material

Load Orientation

Infill

Wall Count

Section Width

Section Height

Line Width

How We Calculate This

Strength Estimation

Effective area = Wall area + (Infill area x Infill%)
Effective density = Effective area / Total cross-section area
Tensile strength = Material tensile x Effective density x Orientation factor
Break force = Tensile strength x Total area

The calculation accounts for the hollow interior of printed parts by computing the effective solid material fraction. The orientation factor reduces strength when loads act across layer lines.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Always verify settings with test prints before committing to final prints.