Filabase 3D Printing Filament Database Articles

Filament Impact Resistance Comparison: PLA vs PETG vs PC vs Nylon

Short answer: For impact resistance and drop survival, Nylon (PA) and PC lead the pack, but in different ways. PC delivers the highest median impact strength at 34.8 kJ/m², and tough nylon grades reach up to 142 kJ/m². PETG is genuinely tougher than PLA despite lower averages — its ductility absorbs shock better. Standard PLA is the most brittle of the four, with a median of only 13 kJ/m², though engineered tough-PLA variants can match or exceed PETG. The material family matters less than the specific grade.
Based on 397 materials with impact data — 223 PLA, 76 PETG, 27 PC, and 44 PA (nylon) filaments — in the Filabase database. Impact strength data reported as kJ/m² (Charpy unnotched or Izod equivalent unless otherwise noted). Last updated: 2026-03-20.

What Impact Resistance Actually Measures

Impact resistance quantifies how much energy a material absorbs before fracturing under sudden load. The two standard tests are the Charpy impact test (a pendulum strikes a supported beam) and the Izod impact test (the pendulum strikes a cantilevered specimen). Both produce results in kJ/m² or J/m, though filament datasheets use kJ/m² more commonly.

For 3D printing, these numbers translate directly to real-world behavior: will your printed part crack when dropped, shatter under vibration, or survive a tool strike? High impact resistance means the material deforms and absorbs energy. Low impact resistance means it fractures suddenly — the part shatters rather than bends.

There's an important distinction between notched and unnotched Charpy values. Unnotched specimens (no pre-cut groove) give higher numbers — they test the material's bulk toughness. Notched specimens simulate stress concentrators like corners, holes, or layer lines — they're closer to real-world FDM part behavior. When comparing materials, always check which test was used.

PLA: Brittle by Default, Tough by Design

Standard PLA has a reputation for brittleness, and the data confirms it. Across 223 PLA filaments in the Filabase database with impact data, the median impact strength is 13 kJ/m² — the lowest of the four materials in this comparison. Standard and silk variants cluster at the low end:

What those averages hide is the dramatic variance within the PLA family. Engineered tough-PLA and PLA+ grades reach values that rival PETG and sometimes surpass standard nylon:

The MatterHackers PRO Series Tough PLA at 160 kJ/m² outperforms most standard nylon and all standard PC grades in raw impact strength. This is not standard PLA — these are reformulated blends with rubber or impact modifiers. But they print at similar temperatures and don't require enclosures.

Key takeaway for PLA: If you need impact resistance, don't buy standard PLA. The difference between a 3.6 kJ/m² silk PLA and an 80+ kJ/m² tough PLA is enormous. Choose a designated tough-PLA or PLA+ grade specifically engineered for ductility.

PETG: More Ductile Than Its Numbers Suggest

PETG's median impact strength across 76 filaments is 8.9 kJ/m² — lower than PLA's median of 13 kJ/m². That seems counterintuitive given PETG's reputation as the tougher material. The explanation lies in the data distribution: PETG's average is actually 41 kJ/m², pulled up by several high-performing grades, while a cluster of standard commodity PETG grades post low numbers similar to basic PLA.

Budget PETG grades from smaller brands often report in the 1–9 kJ/m² range:

Premium and performance PETG grades tell a very different story:

The other factor is PETG's elongation at break — typically 15–50% for standard grades. Even a PETG with moderate impact strength numbers bends rather than shatters, which makes printed parts safer in applications where catastrophic fracture (sharp shards) is a concern. This ductility advantage doesn't show up in raw Charpy numbers but matters for real-world drop resistance.

Key takeaway for PETG: PETG's impact resistance varies enormously by brand and grade. A premium PETG like Elegoo Rapid PETG (87.6 kJ/m²) outperforms most standard nylons. A budget PETG like Eryone Hyper Speed (1.25 kJ/m²) performs worse than basic PLA. Brand selection matters more than material family here.

Polycarbonate: High Impact, High Expectations

PC has the highest median impact strength of the four materials at 34.8 kJ/m², with a mean across 27 filaments of 68.8 kJ/m². In its injection-molded form, PC is one of the toughest engineering polymers — used for bulletproof glass, safety helmets, and phone screens. In FDM printing, layer lines introduce stress concentrators that reduce that toughness, but PC still delivers solid impact performance.

Key PC grades from the database:

There's a notable caveat: PC's impact performance in FDM depends heavily on print quality. PC requires high nozzle temperatures (260–300°C), heated enclosures, and careful moisture management. Poorly printed PC — with weak layer bonds from insufficient temperature or moisture contamination — will perform far worse than these datasheet values suggest. The FlashForge PC at just 4 kJ/m² shows what happens with grades that sacrifice printability: the impact numbers collapse.

PC's Charpy notched values (which better simulate FDM layer-line behavior) are more modest. The Spectrum PC/PTFE posts 12 kJ/m² notched — still respectable, but well below the unnotched numbers that dominate PC marketing materials.

Key takeaway for PC: PC delivers genuine high impact resistance when printed correctly. It requires the most demanding print conditions of the four materials, but when those conditions are met, it offers consistent 55–76 kJ/m² performance from premium grades — enough for functional enclosures, tool handles, and structural brackets.

Nylon (PA): The Widest Range, the Toughest Grades

Nylon presents the most complex picture. Across 44 PA filaments with impact data, the median is 13.5 kJ/m² — comparable to standard PLA. But the maximum values dwarf all other materials: MatterHackers PRO Series Nylon reaches 142 kJ/m², and unfilled PA grades from brands like eSUN hit 75 kJ/m².

The variance comes from nylon's molecular family breadth. PA12 grades (softer, lower HDT) differ substantially from PA6 grades (stiffer, higher HDT), which differ again from high-temperature PAHT or specialty blends. Carbon fiber and glass fiber reinforcement trades some toughness for stiffness.

Standard unfilled PA grades:

Reinforced PA grades using Charpy notched values (from Fiberon testing):

The Fiberon data illustrates the notched/unnotched gap clearly: adding carbon fiber reduces impact resistance in the notched test (because fibers create internal stress concentrators) while the unnotched result stays high. For parts without sharp corners or stress risers, PA-CF performs well. For parts with features that concentrate stress, unfilled nylon may actually outperform CF variants on impact.

Nylon's other impact-relevant advantage is elongation at break. PA grades regularly post 50–200% elongation — far above any PLA, PETG, or PC. This means nylon parts deform visibly before fracturing, absorbing energy through plastic deformation. In drop resistance, this ductility is often more valuable than raw Charpy numbers.

Key takeaway for nylon: The toughest nylon grades — unfilled PA6 and PA66 — are the most impact-resistant material in this comparison. But PA12 and filled grades perform more modestly. If impact resistance is the primary criterion, choose an unfilled PA6 or PA66 grade, not a carbon-filled PA12.

Charpy vs Izod: Which Test Are You Reading?

Most filament datasheets report impact strength as a single number without specifying the exact test. Before comparing values across brands, identify the test method. Charpy unnotched numbers are the highest; Charpy notched values are lower; Izod notched values are different again and not directly comparable to Charpy.

Spectrum provides both notched and unnotched values for several filaments, illustrating the difference:

When a brand reports 70+ kJ/m² for PC and another brand reports 12 kJ/m², they may be measuring the same base material — one unnotched, one notched. For practical part design, the notched value is more predictive because real parts have corners, holes, and layer interfaces that act as notches.

The FDM Penalty: Layer Lines Are Notches

Every 3D-printed part has layer lines, and layer lines act as stress concentrators — effectively creating a notched specimen regardless of part geometry. This means published impact resistance values from injection-molded reference specimens always overstate what you'll get from FDM parts.

The FDM penalty varies by material:

Print orientation matters significantly for all four materials. A part printed with layers parallel to the impact direction (load applied along Z-axis) will always outperform a part where the impact force tries to separate layer interfaces. For maximum impact resistance in FDM, orient parts so impact loads run through the XY plane, not across layer lines.

Material Selection by Use Case

The right choice depends on what you're building and how it fails:

Phone cases, protective enclosures, camera mounts

These parts need to survive drops from 1–2 meters and absorb impact without shattering into sharp fragments. PETG's ductility (bending instead of shattering) makes it safer for this role than even high-impact-strength materials that fracture cleanly. A quality PETG like Elegoo Rapid PETG (87.6 kJ/m²) or Bambu Lab PETG Translucent (37.4 kJ/m²) handles this well. Tough PLA variants are an alternative if you need easier printing.

Tool handles, jigs, and mechanical fixtures

These see repeated shock loads, sometimes lateral force, sometimes impact at varying angles. Nylon excels here — its combination of toughness and ductility lets it absorb repeated impacts without fatigue cracking. MatterHackers PRO Series Nylon (142 kJ/m²) or an unfilled PA6 grade is ideal. PC is an alternative for parts that also need high stiffness and temperature resistance.

Robotics components, drone frames, structural brackets

For structural parts that need both stiffness and impact resistance, PC is the most consistent choice in the 30–76 kJ/m² range. Elegoo PC (76.5 kJ/m²) and FormFutura Kratos PC (70 kJ/m²) offer predictable high-impact performance. For weight-sensitive applications, PA-CF variants offer a better stiffness-to-weight ratio with 40+ kJ/m² impact strength.

Functional prototypes and decorative parts

Standard PLA is adequate when impact resistance is not a requirement. For prototypes that need to survive light handling, any mid-range PLA or PETG in the 15–30 kJ/m² range is sufficient. The Bambu Lab PLA Basic (26.6 kJ/m²) and Prusament PLA (13 kJ/m²) represent the typical range for standard PLA.

Head-to-Head Summary Table

Property PLA PETG PC Nylon (PA)
Median impact strength 13 kJ/m² 8.9 kJ/m² 34.8 kJ/m² 13.5 kJ/m²
Average impact strength 19.8 kJ/m² 41 kJ/m² 68.8 kJ/m² 26.2 kJ/m²
Best-in-class grade 160 kJ/m² (Tough PLA) 87.6 kJ/m² (Rapid PETG) 76.5 kJ/m² (Elegoo PC) 142 kJ/m² (PRO Nylon)
Typical commodity range 3–16 kJ/m² 2–10 kJ/m² 22–55 kJ/m² 5–30 kJ/m²
Failure mode Brittle fracture Ductile bending Stiff fracture Ductile deformation
Elongation at break 2–15% (standard) 15–50% 2–14% 5–200%
Print difficulty Easy Easy–Moderate Hard (enclosure needed) Moderate (dry filament required)
Drop/shock resistance Poor (standard) / Good (tough grade) Good (quality grade) Very good (when well-printed) Excellent (unfilled PA6/PA66)
Materials with impact data 223 76 27 44

Practical Decision Guide

Rather than choosing a material family, choose a specific performance tier:

What the Numbers Don't Tell You

Impact strength datasheets have real limitations for FDM applications. The test uses injection-molded specimens — isotropic, void-free, with consistent material properties throughout. Printed parts have anisotropic layer structures, variable void content depending on infill, and layer-line stress concentrators that can reduce real-world impact resistance by 30–60% compared to datasheet values.

The practical differences between a well-printed 40 kJ/m² PETG part and a 40 kJ/m² nylon part may matter less than the difference between 40% infill and 80% infill in the same material. Print parameters — particularly layer height, infill density, print temperature, and wall count — often have more influence on drop survival than material selection within the same impact class.

For drop resistance specifically: thicker walls (4+ perimeters), higher infill (40%+), and print orientation with impact loads traveling through XY layers rather than across Z layer lines will all significantly improve real-world performance regardless of which material you choose.

Explore the full interactive database →

Data sourced from manufacturer technical data sheets.