How to Choose a 3D Printing Material: What the Specs Mean and Why One Beats Another

There Is No Best Material, Only the Best Fit

Every material in our catalog is the best choice for some part and the wrong choice for another. PLA beats nylon for a crisp display model; nylon beats PLA for a hinge. The fastest way to choose is to ask one question first: what would make this part fail? Too hot, too much load, too much flexing, sunlight, chemicals, humidity, or simply looking wrong. Pick the material that is strongest in that failure mode, then check the rest of its properties are good enough.

What the Numbers on a Material Card Mean

The specs on our materials page, and on any datasheet, answer different questions:

• Tensile strength (MPa): how much pulling stress the material takes before it breaks. Useful for comparing, but a high number alone does not make a part durable; a strong-but-brittle material can still snap on impact.
• Stiffness / modulus: how much the part deflects under load. Carbon and glass fiber raise stiffness sharply. If your part must not bend, stiffness matters more than strength.
• Elongation at break / toughness: how far the material stretches before it fails. High-elongation materials (nylon, TPU, PC) bend and recover; low-elongation ones (PLA, fiber composites) crack. Toughness is what survives drops and snap-fits.
• Heat resistance: roughly where the material begins to soften under load (heat deflection temperature). PLA softens around 55-60 °C, which a car dashboard in summer easily exceeds; ABS and ASA reach about 100 °C, PC about 140 °C, and PPA-CF about 200 °C.
• Moisture uptake: how much water the material absorbs from the air. It matters for dimensional stability. Nylon PA6 absorbs a lot, PA12 and PET-CF very little.
• Chemical and UV resistance: whether oils, fuels, cleaners or sunlight degrade the part over time. ASA is the UV specialist; PA12, PP and PPS are the chemical specialists.
• Density: lower density means a lighter part for the same volume. It also drives material cost per part.

Why the Printed Part Differs From the Datasheet

Datasheet values are measured on test bars printed under ideal conditions. An FDM part is made of layers, and the bond between layers is weaker than the material itself, so strength in the vertical (Z) direction can be well below the XY figure. Wall count, infill and orientation all matter. That's why we orient parts so the main load runs along the layers, and why design choices like fillets and ribs often do more for a part than switching to a stronger material. See our guide to print orientation and strength for the details.

The Material Families, and What Each Is For

Why One Material Beats Another: Common Match-Ups

The comparisons we're asked about most, and the deciding factor in each:

• PLA vs PETG: PLA prints sharper and costs less; PETG survives heat, impact and chemicals. Indoor model: PLA. Functional part: PETG.
• PETG vs PCTG: same easy printing, but PCTG is several times tougher in impact. If the part will be dropped or struck, PCTG.
• ABS vs ASA: nearly identical mechanically, but ASA does not yellow or embrittle in sunlight. Outdoors, always ASA.
• ABS vs PC-ABS vs PC: each step adds strength and heat resistance. PC-ABS is the sweet spot for electronics housings; pure PC when you need the highest heat or strength.
• Nylon vs PC: both strong. Nylon wins on toughness, fatigue and wear (gears, hinges); PC wins on stiffness, heat and dimensional stability (housings, brackets).
• PA6 vs PA12: PA6 is tougher; PA12 holds its dimensions in humidity and resists fuels and oils. See our nylon grade guide for the full comparison.
• Carbon fiber vs glass fiber: CF is stiffer and lighter; GF is tougher, cheaper, insulating and radio-transparent.
• TPU 85A vs 95A vs 64D: softer grips and seals better, harder holds shape and prints finer detail. 95A is the all-rounder.
• FDM vs SLA: FDM thermoplastics are tougher and better for load-bearing parts; SLA resins win on fine detail and surface finish.

A Quick Decision Guide

Cost: Where the Money Goes

Material price per kilogram is only part of a part's cost. Difficult materials take longer to print, need dried filament, heated chambers or hardened nozzles, and fail more often, and the price reflects that. That's why a nylon or carbon-fiber part costs more than the filament difference alone suggests. The cheapest good part usually comes from picking the least demanding material that meets every requirement, not the strongest one available.

Still Unsure? Ask Before You Print

Upload your file and pick the closest material; the quote is instant and you can switch materials on the quote page to compare prices. Add a note on load, temperature and environment, and our engineers will flag a better choice before printing. Browse every material with its specs on our materials page.