PLA is stronger than PETG in tension and more rigid; PETG is tougher and handles heat better. In Prusa’s matched datasheets, printed PLA yields at 51 to 59 MPa against PETG’s 47 to 50 MPa, and PLA’s tensile modulus is 2.3 to 2.4 GPa against 1.5 to 1.6 GPa.
Most petg vs pla strength comparison articles repeat the same two lines: PETG is “tougher,” PLA is “more rigid,” and neither claim gets a number attached. Prusa Polymers publishes matched technical datasheets for Prusament PETG and Prusament PLA, both tested on the same printer (Original Prusa i3 MK3), the same slicer, and the same ISO methods (ISO 527-1 for tensile, ISO 178 for flexural, ISO 179-1 for Charpy impact). That’s about as close to apples-to-apples as filament data gets, and the numbers don’t fully back up the marketing shorthand.
PETG vs PLA strength at a glance
All figures are from printed specimens. The PolyLite columns come from Polymaker’s PolyLite PLA and PolyLite PETG datasheets, tested to the same ISO methods. “n/a” marks a property that datasheet reports with a different test, or one not reproduced here.
| Property | Prusament PLA | Prusament PETG | PolyLite PLA | PolyLite PETG |
|---|---|---|---|---|
| Tensile strength, flat (XY) | 51 ± 3 MPa (yield) | 47 ± 2 MPa (yield) | 52.3 ± 0.3 MPa | 50.8 ± 0.9 MPa |
| Tensile strength, on edge (XZ) | 59 ± 2 MPa | 50 ± 1 MPa | n/a | n/a |
| Tensile strength, across layers (Z) | n/a | n/a | 40.5 ± 0.5 MPa | 42.8 ± 2.8 MPa |
| Tensile (Young’s) modulus, XY | 2.3–2.4 GPa | 1.5–1.6 GPa | 3,426.9 MPa | 2,116.8 MPa |
| Bending modulus, XY | 3.1 GPa | 1.7 GPa | 3,230.9 MPa | 1,898.5 MPa |
| Bending strength, XY | 83 MPa | 66 MPa | 86.9 MPa | 69.6 MPa |
| Elongation | 2.9–3.2% at yield | 5.1% at yield | 6.3% at break | 8.4% at break |
| Charpy impact | 13–14 kJ/m² unnotched | No break unnotched; 3–6 kJ/m² notched | 3.3 kJ/m² notched | 2.6 kJ/m² notched |
| Interlayer adhesion | 17 ± 3 MPa | 18 ± 4 MPa | n/a | n/a |
| Heat deflection temperature | 55 °C | 68 °C | 60 °C (0.45 MPa) | 78 °C (0.45 MPa) |
Both vendors agree on the shape of the answer. PLA leads on flat tensile strength (by 4 MPa at Prusa, 1.5 MPa at Polymaker) and on stiffness everywhere. PETG leads on heat deflection by 13 to 18 °C and, in Polymaker’s vertical bars, across the layers: 42.8 against 40.5 MPa, keeping 84 percent of its flat strength where PLA keeps 77 percent. Polymaker’s bars were printed at 100 percent infill, so treat them as best-case parts.
Tensile strength: closer than the reputation suggests
On raw filament (unprinted, pulled per ISO 527), PLA comes in at 57 ± 1 MPa tensile yield strength versus PETG’s 46 ± 1 MPa. That gap looks decisive until you print actual test bars. On printed specimens, PETG lands at 47 ± 2 MPa printed flat and 50 ± 1 MPa printed on edge (vertical XZ); PLA prints at 51 ± 3 MPa flat and 59 ± 2 MPa on edge. PLA still wins on pure tensile yield, but the margin in printed parts (4 MPa flat, 9 MPa on edge) is a lot narrower than the “PLA is way stronger” framing implies.
Where the two actually diverge is stiffness, not strength. PLA’s tensile modulus is 2.3-2.4 GPa against PETG’s 1.5-1.6 GPa, and PLA’s elongation at yield is only 2.9-3.2% compared to PETG’s 5.1%. PLA is the stiffer material that resists deformation up to a point, then yields with less warning. PETG stretches further before it gets there. If your part needs to hold a precise dimension under light load, PLA’s higher modulus is the relevant number, not tensile strength.
How strong is PETG filament?
Printed PETG reaches about 47 to 51 MPa tensile strength along the layers on vendor datasheets: 47 to 50 MPa for Prusament PETG and 50.8 MPa for PolyLite PETG, dropping to 42.8 MPa when pulled across the layers. Molded Eastman Eastar 6763 PETG resin yields at 48.0 MPa, so a well-fused solid print gets close to the bulk material.
Independent labs report a wider spread. Guessasma and colleagues printed PETG on a MakerBot Replicator 2 with a ±45° raster at 240 and 250 °C and measured 32.3 to 34.0 MPa, roughly 60 percent of the 54.3 MPa reported for the as-received material. Demir and colleagues (2024), printing PETG at 260 °C through a 0.2 mm nozzle, measured 54.9 MPa against 59.9 MPa for PLA from the same supplier. A fair working range for printed PETG in tension is 30 to 55 MPa, depending on printer, raster direction and temperature.
PETG yield strength vs tensile strength
PETG’s yield strength is about 46 to 50 MPa for solid material. Prusa lists 46 ± 1 MPa for unprinted filament and 47 to 50 MPa for printed bars, and molded Eastar 6763 yields at 48.0 MPa at 4.2 percent strain. Yield is the stress at which the plastic stops springing back; for PETG it arrives well before the part breaks.
The gap between yield and break is what separates the two. Eastar 6763 stretches 50 percent or more before breaking, while PLA yields at 2.9 to 3.2 percent strain in Prusa’s data and PolyLite PLA breaks at 6.3 percent. Past its yield point, a PETG clip is more likely to stay bent than to snap.
Partial infill pulls yield far below the solid-bar number. Kumaresan and Kanny (2025) printed PolyLite PETG at 240 °C and 50 percent infill and measured 0.2 percent offset yield strengths of 5.43 to 21.01 MPa across 46 combinations of infill pattern and raster angle, with ultimate tensile strength peaking at 43.09 MPa. Treat any datasheet yield value as an upper bound for parts below 100 percent infill.
Is PETG more rigid than PLA?
No. PLA is roughly 1.4 to 1.8 times as stiff as PETG in every matched dataset. Polymaker lists a bending modulus of 3,230.9 MPa for PolyLite PLA against 1,898.5 MPa for PolyLite PETG, Prusa gives tensile modulus of 2.3 to 2.4 GPa against 1.5 to 1.6 GPa and bending modulus of 3.1 against 1.7 GPa, and the Demir study measured flexural modulus of 3,033.9 against 1,760.1 MPa.
Rigidity is a modulus property, and it shows up as deflection long before anything breaks. With the same geometry and the same light load, deflection scales inversely with modulus, so a PETG shelf bracket sags about 1.7 times as far as an identical PLA one. PLA also carries more in bending before it gives: 86.9 MPa bending strength against 69.6 MPa in Polymaker’s data, and 96.9 against 69.8 MPa in the Demir study.
To get PLA-like stiffness from PETG, add material where the part bends: bending stiffness of a rectangular section scales with the cube of its thickness, so a PETG beam about 19 percent thicker offsets a 1.7-times modulus gap. Wider inner-wall lines help too, as the nozzle size and layer height guide explains.
Impact strength: this is where PETG earns its reputation
Charpy impact testing is where the two materials split hardest. On the unnotched Charpy test, PETG specimens didn’t break at all, in either print orientation. PLA specimens did break, registering 13 ± 1 kJ/m² (flat) and 14 ± 1 kJ/m² (on edge). Notch a PETG specimen first and it breaks too, at 6 ± 1 kJ/m² flat and 3 ± 1 kJ/m² on edge; Prusa doesn’t list a notched value for PLA at all.
That pattern matches what’s documented more broadly in FDM literature: PLA tends to fail abruptly through brittle fracture, while PETG deforms before it finally lets go. The PMC study on PET-G and PLA processing parameters reinforces this indirectly through its process sensitivity data (below), but the Prusament unnotched-vs-notched contrast is the cleanest single data point: PETG’s toughness advantage is real and it’s specifically an impact/toughness property, not a tensile-strength property.
Polymaker’s notched-only figures add a caveat: PolyLite PLA scores 3.3 kJ/m² against 2.6 kJ/m² for PolyLite PETG. PETG’s toughness is a blunt-impact property that a sharp notch largely cancels, so give PETG clips and snap-fits rounded internal corners.
The number that actually predicts layer failures
Interlayer adhesion is the property that decides whether a functional part delaminates under load, and it’s the one most comparison posts skip. Prusa’s own testing puts PETG interlayer adhesion at 18 ± 4 MPa and PLA at 17 ± 3 MPa. That’s within each other’s error bars. If you’ve read that PETG bonds layers dramatically better than PLA, this vendor’s own numbers don’t support “dramatically” — they support “roughly the same, printed correctly.” Print quality (nozzle temperature, cooling, and part cooling fan speed) will move interlayer adhesion further than switching material will.
Shear loads find the same weak plane. Neither the PolyLite PETG sheet nor the Eastar 6763 resin data lists a shear strength; the handbook figure on MakeItFrom’s PETG page is 62 MPa, for solid material with no test method stated, which says little about printed layers. For a pin through a printed lug or a bolted tab, orient the part so the shear plane cuts across the layers rather than along a layer line.
Orientation, infill, and temperature move the numbers more than the material choice
A 2022 study on FDM PET-G and PLA processing parameters tested how print settings affect specific tensile strength (strength normalized for part weight) across both materials and found the process variables matter as much as the resin choice. Raising nozzle temperature increased specific tensile strength for both materials, but the effect was more than double for PLA (a 27.53% increase) compared to PETG (12.69%). Infill density pushed absolute tensile strength up for both — 37.27% for PLA and 24.42% for PETG at maximum infill — while cutting the strength-to-weight ratio in both cases, since added plastic mass outpaces the strength gain. Print orientation had the largest swing of any variable: parts printed flat (XY) consistently outperformed parts printed on edge (XZ), and PLA showed a bigger orientation penalty (58.21% variation) than PETG (29.29%).
The practical read: a petg vs pla strength comparison done at default slicer settings and one done at a tuned, temperature-optimized, high-infill profile can produce noticeably different rankings. PLA gains more from a good profile than PETG does, and loses more from a bad one. Nozzle temperature is the easiest of those variables to change, so run a temperature tower on each spool before judging either material by a broken part.
Print settings behind these numbers
Prusa’s datasheets list the exact recommended settings used to generate the results above:
- PETG: nozzle 250 ± 10°C, bed 80 ± 10°C, cooling fan 50%, up to 200 mm/s
- PLA: nozzle 210 ± 10°C, bed 40-60°C, cooling fan 100%, up to 200 mm/s
PETG also has a materially higher heat deflection temperature (68°C at both 0.45 and 1.8 MPa load) versus PLA (55°C), which matters more than either tensile number if the part sits somewhere warm — a car dashboard mount, a lampshade near an incandescent bulb, or an enclosure over anything that generates heat.
Picking one for a given part
For anything that takes a drop, a snap-fit, or repeated flex — brackets, hinge clips, phone mounts, outdoor fixtures — PETG’s impact behavior and higher heat deflection temperature are the deciding factors, not tensile strength. For dimensionally precise, stiff parts printed indoors at room temperature — jigs, enclosures, most Etsy-shop decorative and functional prints — PLA’s higher modulus, easier bed adhesion, and lower nozzle/bed temps make it the more practical default. Neither material is “stronger” in every sense that matters; they trade tensile yield for toughness and stiffness for ductility, and the print settings you actually use move those numbers more than the datasheet implies.
Two settings dominate that gap. Spool condition can affect print quality; use 3D Filament Guide’s drying chart for conditioning and the dry-box and chamber workflow to keep calibration conditions consistent, and both materials change behaviour with ambient temperature, listed per material in the chamber temperature reference. Larger PETG parts also lift at the corners more readily than PLA, and the ranked fixes for that are in why prints warp at corners.
Cost, and the Decision Above This One
The two materials are close enough in spool price that cost rarely decides between them on its own, but the part cost can differ more than the spool cost suggests, because PETG’s higher printing temperatures and typically slower speeds change the electricity and machine-time side of the total. The print time and filament cost estimator prices the same model in either material with its density and speed ceiling already applied, which is a better basis for the comparison than the price per kilogram.
There is also a decision sitting above this one. If the part’s requirement is fine surface detail rather than mechanical strength, neither filament is really the answer and the question becomes a process choice rather than a material choice — that trade is worked through in the FDM vs resin decision framework.
Whichever material you settle on, the strength figures above only hold if the printer is actually extruding what the slicer asked for. Layer bonding in particular is sensitive to under-extrusion and to melt temperature, so run the sequence in the 3D printer calibration order before drawing conclusions from a part that broke.
FAQ
Is PETG stronger than PLA?
No, not in tension. Prusa’s matched datasheets put printed PLA at 51 to 59 MPa and PETG at 47 to 50 MPa, and PLA is roughly 1.4 to 1.8 times stiffer. PETG wins on toughness: unnotched PETG Charpy bars did not break at all, while PLA broke at 13 to 14 kJ/m². PETG also resists heat better.
What is the shear strength of PETG?
Handbook data puts solid PETG at 62 MPa in shear, but filament datasheets such as Polymaker’s PolyLite PETG and the Eastar 6763 resin data don’t list shear strength at all. In a printed part the weak shear plane runs between layers, where Prusa’s testing puts PETG interlayer adhesion at 18 ± 4 MPa.
Does PETG have better layer adhesion than PLA?
Barely, and not enough to matter. Prusa’s testing puts PETG interlayer adhesion at 18 ± 4 MPa and PLA at 17 ± 3 MPa, figures that sit inside each other’s error bars. The claim that PETG bonds layers dramatically better is not supported by that data. Nozzle temperature, cooling, and part-cooling fan speed move interlayer adhesion further than switching material.
Does PETG handle heat better than PLA?
Yes, by a margin that often decides the material choice. PETG’s heat deflection temperature is 68°C at both 0.45 and 1.8 MPa, against 55°C for PLA. For a part that sits somewhere warm, such as a car dashboard mount, a lampshade near an incandescent bulb, or an enclosure over electronics, that 13-degree gap matters more than either tensile figure.
Which filament should be used for functional parts?
PETG for parts that take impact or heat, PLA for stiff, precise indoor parts. Brackets, hinge clips, phone mounts and anything outdoors favour PETG for its impact behaviour and heat resistance. Jigs, fixtures and enclosures that must hold a dimension favour PLA for its higher modulus, easier bed adhesion and lower print temperatures.
