PLA and PETG are the two filaments most desktop printers are set up for first, and both print on an open-frame machine. The practical question is what the finished part has to survive. A display model on a shelf asks very little of its material; a bracket in a sunny window, a box that gets wet, or a clip that must bend before it breaks asks a lot more.
This comparison uses one supplier's grades of both materials so the numbers line up: Polymaker PolyLite PLA and PolyLite PETG, which were printed and tested with the same ISO methods. Prusa's material guides add printing settings and handling notes. Other brands, blends and colors will differ, so treat these as a starting point and check the data sheet for the spool you actually buy.
PLA and PETG side by side
| Property | PLA | PETG |
|---|---|---|
| Nozzle temperature | 190–230 °C (PolyLite PLA); Prusa: 215 °C first layer, 210 °C after | 230–260 °C (PolyLite PETG); Prusa: 230 °C first layer, 240 °C after |
| Bed temperature | 25–60 °C (PolyLite PLA); Prusa: 60 °C | 70–80 °C (PolyLite PETG); Prusa: 85 °C first layer, 90 °C after |
| Enclosure and part cooling | Enclosure not needed; cooling fan on (Polymaker) | Enclosure not needed; cooling fan off to 20% (Polymaker) |
| Heat deflection, ISO 75 (1.8 / 0.45 MPa) | 58 °C / 60 °C | 75 °C / 78 °C |
| Vicat softening, ISO 306 | 63 °C | 84 °C |
| Tensile strength, ISO 527 (X-Y / Z) | 52.3 / 40.5 MPa | 50.8 / 42.8 MPa |
| Tensile modulus, ISO 527 (X-Y) | 3426.9 MPa | 2116.8 MPa |
| Elongation at break (X-Y / Z) | 6.3% / 1.8% | 8.4% / 3.3% |
| Notched Charpy impact, ISO 179 (X-Y) | 3.3 kJ/m² | 2.6 kJ/m² |
| UV and outdoor use | Prusa: degrades under UV light; not suitable for outdoor use | Prusa: suitable for most exterior use below 80 °C; UV resistance not stated |
| Drying | 55 °C for 6 h (Polymaker); Prusa lists 45 °C for 6 h for Prusament PLA | 65 °C for 6 h (Polymaker); Prusa lists 55 °C for 6 h for Prusament PETG |
| Build surface | PC or textured PEI (Polymaker); Prusa: satin or smooth PEI | PC or textured PEI (Polymaker); Prusa warns smooth PEI may be damaged |
Property values come from Polymaker's PolyLite PLA and PolyLite PETG technical data sheets (same test methods, 100% infill specimens), with printing guidance from Prusa's PLA, PETG, drying and enclosure articles.
Heat resistance
Heat is where the two materials separate most clearly. Polymaker lists a heat deflection temperature of 58 °C for PolyLite PLA and 75 °C for PolyLite PETG under the 1.8 MPa ISO 75 load, and Vicat softening points of 63 °C and 84 °C. Prusa's guidance points the same way: its PLA article says the material softens and deforms above roughly 60 °C, while its PETG article describes parts as suitable for most exterior use below 80 °C.
These are test-bar values under a defined load, not a promise about a specific part. A thin wall under a clamp load can creep below the listed temperature. If the part will sit in a car, near a motor or in direct sun, compare the expected temperature with the exact grade's data and leave a margin.
Strength, stiffness and toughness
In the PolyLite data, the two materials have similar in-plane tensile strength (52.3 MPa for PLA, 50.8 MPa for PETG), but PETG holds up slightly better across layers in the Z direction (42.8 MPa against 40.5 MPa) and stretches further before breaking. PLA is much stiffer, with a tensile modulus of about 3,427 MPa against about 2,117 MPa for PETG, so a PLA part deflects less under the same load.
Polymaker's notched Charpy values are low for both and slightly lower for PETG. Prusa describes PLA as brittle, breaking along layers or into shards on impact, and credits PETG with good layer adhesion. Polymaker notes its values are for reference and comparison, not design specification, so a useful check is to print the real part in its intended orientation and load it the way it will be used.
Printing differences
PETG runs hotter at both the nozzle and the bed. Polymaker suggests a cooling fan for PLA but little or no fan for PETG. Prusa's enclosure guide classes both as low-temperature filaments whose shrinkage is too small to notice during printing, so neither needs an enclosure.
The build plate deserves attention with PETG. Prusa recommends a textured or satin sheet and warns that PETG printed on smooth PEI can damage the sheet; it suggests a glue stick as a separation layer if smooth PEI is the only option.
Outdoor use and moisture
Prusa states that PLA degrades under UV light and is not suited to outdoor use. Its PETG article lists water and humidity resistance among PETG's strengths and mentions waterproof parts as a use, though it does not give a UV rating.
Both filaments benefit from dry storage. Polymaker recommends drying PolyLite PLA at 55 °C for 6 hours and PolyLite PETG at 65 °C for 6 hours, while Prusa's drying table gives lower temperatures for its own Prusament grades. Use the figures for the brand you are drying.
Which should you choose?
Choose PLA if…
- The part is a concept model, figure or display piece where surface detail matters more than toughness.
- The part stays indoors and well below the roughly 60 °C range where Prusa says PLA softens.
- Stiffness matters: PolyLite PLA's tensile modulus is about 60% higher than PolyLite PETG's.
- You want a low bed temperature and active part cooling for crisp overhangs.
Choose PETG if…
- The part will see warmth up to the mid-70s °C range listed for PolyLite PETG's heat deflection temperature.
- The part is used outdoors or around water, where Prusa rules PLA out and describes PETG as suitable.
- You need holders, clamps, boxes or other functional parts that should bend a little before failing.
- Layer-to-layer strength matters, since PETG's Z-direction tensile strength is higher in the PolyLite data.
Common questions
Is PETG stronger than PLA?
It depends on the measure. In Polymaker's PolyLite data, in-plane tensile strength is similar (52.3 MPa for PLA, 50.8 MPa for PETG), PETG is stronger across layers, and PLA is considerably stiffer. Prusa describes PLA as the more brittle of the two.
Can PLA parts go outside?
Prusa says PLA degrades under UV light and is not suitable for outdoor use. Prusa's PETG guide, by contrast, describes PETG parts as suitable for most exterior uses below 80 °C.
Does PETG need an enclosure?
No. Polymaker lists the enclosure as not needed for PolyLite PETG, and Prusa's enclosure guide groups PETG with PLA as low-temperature filaments that print without one.
Sources
- PolyLite PLA technical data sheet Polymaker · Checked 2026-11-02
- PolyLite PETG technical data sheet Polymaker · Checked 2026-11-02
- PLA Prusa Research · Checked 2026-10-15
- PETG Prusa Research · Checked 2026-10-15
- Drying filament Prusa Research · Checked 2026-10-15
- Enclosure guidepost Prusa Research · Checked 2026-10-16
This comparison summarizes the cited documentation; it is not a lab test. Properties vary by brand, grade, print settings and orientation, so check the data sheet for the exact product you buy.