PETG has a tensile strength of 40 to 50 MPa, placing it between PLA and ABS in raw pulling force but ahead of both in overall durability. It resists impacts without shattering, bends before it breaks, and holds up at higher temperatures than PLA. For most functional 3D-printed parts, PETG offers the best balance of strength and toughness among the three most common filaments.
Tensile Strength Compared to PLA and ABS
Tensile strength measures how much pulling force a material can handle before it snaps. PETG lands at 40 to 50 MPa, which is lower than PLA’s 50 to 60 MPa but noticeably higher than ABS at 34 to 36 MPa. On paper, PLA looks like the stronger material. In practice, that number only tells part of the story.
PLA is rigid and brittle. It resists being pulled apart but shatters under sudden force. PETG absorbs significantly more energy from impacts without cracking, which is why parts that get dropped, bumped, or loaded unpredictably tend to survive longer when printed in PETG. ABS also handles impacts well, but its lower tensile strength and tendency to warp during printing make PETG the more practical choice for most users.
Flexural Strength and Stiffness
Flexural strength describes how well a material resists bending before it permanently deforms or breaks. Optimized PETG prints reach a flexural strength around 39.5 MPa and a flexural modulus (a measure of stiffness) near 1,345 MPa. That modulus is lower than PLA’s, which means PETG parts flex more under load instead of snapping. For structural brackets, clips, or enclosures that need to absorb some give without failing, this is an advantage.
The layer height you choose has the biggest influence on stiffness, accounting for roughly 80% of the variation in flexural modulus. Thinner layers generally produce stiffer parts. Nozzle temperature, meanwhile, is the dominant factor for flexural strength itself, contributing about 57% of the outcome.
How Printing Temperature Affects Strength
PETG’s real-world strength depends heavily on how well its layers fuse together. A flat-printed PETG sample can reach about 55 MPa in tensile strength, but when the same part is printed standing upright so that loads pull layers apart, the story changes dramatically.
At 200°C, layer bond strength drops to just 18 MPa, roughly a third of the material’s full potential. Bumping the nozzle to 230°C brings that up to 30 MPa (about 55% of reference strength), and printing at 245°C pushes it to 32 MPa (60%). Going too far in the other direction hurts: samples printed at 260°C dropped back down to 24 MPa, because excessive heat degrades the material during extrusion.
The practical takeaway is to print at the upper end of your filament’s recommended range, around 245 to 255°C for most PETG brands. Increase in 5°C increments and watch for stringing. Running too cool is the more common mistake and costs you the most strength. Parts printed at the low end of the temperature window can be less than half as strong between layers as those printed at the ideal temperature.
Heat Resistance
PETG’s glass transition temperature sits between 80 and 85°C. Below that threshold, the material behaves like a rigid solid. Above it, PETG softens, becomes flexible, and loses structural integrity. That’s a meaningful upgrade over PLA, which starts deforming around 55°C and can warp in a hot car on a summer day.
ABS outperforms both, holding its shape up to roughly 98°C. But for most indoor and moderate-outdoor applications, PETG’s 80°C threshold is sufficient. Parts near heat sources like electronics enclosures or engine-adjacent mounts may need ABS or a higher-performance material.
UV and Outdoor Durability
PETG is sometimes recommended for outdoor use, but UV exposure degrades it significantly. In accelerated aging tests simulating several months of sun exposure, PETG parts lost 36% of their tensile strength and 38% of their compressive strength. The material’s stiffness stayed roughly the same (dropping from 1,648 MPa to 1,629 MPa), so parts don’t feel softer, but they break under much less force.
Functional parts like clamps or fasteners showed measurable weakening within a single week. Clamping force dropped by 11.5% after one week and continued declining to 21.3% below the original value. PLA, surprisingly, held up better in the same UV tests, losing only about 5 to 6% of its strength. If your PETG parts will live outdoors, a coat of UV-resistant paint or a pigmented filament (which blocks more UV than translucent colors) helps slow this degradation.
Chemical Resistance
PETG handles mild bases and weak alkalis reasonably well but is vulnerable to a wide range of organic chemicals. Strong acids, alcohols, ketones, esters, and aromatic hydrocarbons all attack PETG and can cause cracking, clouding, or structural failure. The one category where PETG performs well is aliphatic hydrocarbons (simple petroleum-derived solvents like hexane), where it actually outperforms standard PET.
For parts that contact oils, greases, or common workshop solvents, PETG offers only moderate resistance. If your application involves regular chemical contact, check compatibility for the specific substance rather than assuming PETG can handle it.
Maximizing PETG Part Strength
Print settings have a larger effect on final strength than most people expect. A poorly printed PETG part can perform at one-third of its potential, while an optimized one approaches the material’s full capability. The most impactful variables, in order of importance:
- Nozzle temperature: Print at the upper end of the recommended range (typically 240 to 255°C). This is the single biggest lever for layer adhesion, which is usually the weakest link in any printed part.
- Layer height: Thinner layers (around 0.15 to 0.20 mm) increase stiffness and flexural modulus. For maximum strength rather than speed, keep layers on the thinner side.
- Part orientation: Orient parts so that expected loads run along the print lines rather than pulling layers apart. A part loaded across its layers can be half as strong as the same part loaded along them.
- Cooling: PETG benefits from less part cooling than PLA. Reducing fan speed helps layers stay warm enough to bond properly, improving interlayer fusion.
- Wall count and infill: More perimeter walls add strength more efficiently than increasing infill percentage. Three to four walls with 20 to 40% infill covers most functional applications.
PETG won’t match polycarbonate or nylon for extreme loads, but for the vast majority of functional prints, it delivers a combination of toughness, heat tolerance, and printability that neither PLA nor ABS can match across the board.