PLA and PETG are the two most common desktop FDM filaments: PLA is a stiff, easy-to-print plastic that softens at about 60 °C, while PETG is a glycol-modified polyester that holds its shape to roughly 70–80 °C and flexes more before it breaks. Pick PLA for models, prototypes and parts that stay cool and indoors. Pick PETG for parts that get warm, wet, flexed or knocked around.
Raw strength is not the deciding factor. Polymaker’s data sheets give 52.3 MPa tensile strength for PolyLite PLA and 50.8 MPa for PolyLite PETG in the XY direction, which is close to a tie. What separates the two is heat resistance, how a part fails, and how fussy each one is to print. The numbers below come from Polymaker data sheets and the Prusa Knowledge Base, linked at the end; where a value is our own suggestion rather than a published figure, we say so.
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PLA or PETG in 30 seconds
- Choose PLA for display models, prototypes, jigs and templates, and anything that needs to be stiff and print cleanly on the first try.
- Choose PETG for enclosures near heat, clips and snap-fits that flex, parts exposed to water or humidity, and functional parts that may be dropped.
- Choose neither if the part sits above roughly 70–80 °C or in direct sun for years. Look at ASA, ABS or PC instead (see our high-strength filament guide).
PLA vs PETG data sheet comparison
The table uses one manufacturer, Polymaker, for both materials so the test method is the same. Printed specimens were 100% infill with two shells; PLA was printed at 230 °C with the fan on, PETG at 240 °C with the fan off. XY means the layers lie along the pull direction, Z means the pull runs across the layer lines.
| Property | PolyLite PLA | PolyLite PETG |
|---|---|---|
| Density | 1.17 g/cm³ | 1.25 g/cm³ |
| Glass transition (DSC) | 61 °C | 81 °C |
| Vicat softening | 63 °C | 84 °C |
| Heat deflection, 0.45 MPa / 1.8 MPa | 60 °C / 58 °C | 78 °C / 75 °C |
| Tensile strength XY / Z | 52.3 / 40.5 MPa | 50.8 / 42.8 MPa |
| Elongation at break XY / Z | 6.3 / 1.8 % | 8.4 / 3.3 % |
| Young’s modulus XY (stiffness) | 3,427 MPa | 2,117 MPa |
| Notched Charpy impact XY | 3.3 kJ/m² | 2.6 kJ/m² |
| Recommended nozzle / bed | 190–230 °C / 25–60 °C | 230–260 °C / 70–80 °C |
| Recommended part cooling fan | On | Off to 20% |
| Drying | 55 °C for 6 h | 65 °C for 6 h |
Polymaker states that these are typical values for reference and comparison, not for design or quality control, and other brands will differ. Read the table as a pattern, not as a guarantee for your spool.
Heat resistance: the clearest difference
Prusa says PLA “gets soft and deforms at temperatures over 60 °C”, which matches the 61 °C glass transition above. PETG gives you more room, but vendors disagree on how much: Prusa’s PETG article says it suits most indoor and exterior uses provided temperatures stay below 80 °C, Prusament PETG is listed at 68 °C temperature resistance, and Polymaker measures a heat deflection temperature of 75–78 °C.
When three sources give three numbers, design for the lowest one. As our own rule of thumb rather than a published limit: keep a loaded PETG part well under 68 °C, and treat 60 °C as the ceiling for PLA. A part that can pass those temperatures, for example near a heater, a power supply or in a closed car in summer sun, should not be PLA.
Strength, stiffness and how each one breaks
PLA is the stiffer material: Polymaker lists a Young’s modulus of about 3,427 MPa against 2,117 MPa for PETG. That is why a PLA jig or template feels rigid, and why a PLA clip snaps instead of bending. Prusa describes PLA as breaking “along layers or into shards upon impact” with weaker layer adhesion than other materials, and PETG as tenacious and flexible, often only bending temporarily.
The data sheet shows the same thing in elongation: PETG stretches 8.4% (XY) and 3.3% (Z) before breaking against 6.3% and 1.8% for PLA. One caution: in Polymaker’s notched Charpy test PETG scores lower (2.6 against 3.3 kJ/m²), so “PETG is tougher” is true for flexing and bending, not for every impact test. In both materials the Z values are the weak spot, which is why print orientation matters more than the choice between them (see print orientation for strength).
To make a PETG part stronger Prusa recommends adding perimeters rather than infill, and printing with the part cooling fan off for maximum layer bonding. If PLA parts snap or split along layers, brittle PLA covers moisture and settings.
Printing differences you will notice
| PLA | PETG | |
|---|---|---|
| Nozzle (Prusa) | 215 °C first layer, 210 °C after | 230 °C first layer, 240 °C after |
| Bed (Prusa) | 60 °C; a heated bed is optional | 85 °C first layer, 90 °C after; heated bed required |
| Part cooling | On (Polymaker) | Off for the first layers, then about half power; off for maximum strength (Prusa) |
| Bed surface | Satin or smooth PEI; glass and a glue stick also work | Textured or satin sheet. Smooth PEI can grip so hard that removal damages the sheet; use a glue stick there |
| Stringing | Sometimes | More prone; Prusa suggests more retraction and a lower nozzle temperature |
| Bridges and overhangs | Better | Weaker than PLA (Prusa) |
| Warping | Low | Low; Prusament lists “almost no warping” |
The spool label and your printer’s profile win over any table. Start from the label and adjust in 5 °C steps with a temperature tower. For PETG-specific tuning (retraction, fan, stringing) use our PETG print settings guide; for the plate side, see PEI vs glass plates.
One widespread claim is worth dropping: standard PETG is not abrasive. Prusament’s PETG page lists abrasivity as “None”, so a brass nozzle is fine. Carbon-fibre or glass-fibre filled grades are a different matter.
Outdoor, water and food contact
- UV and weather: Prusa lists PLA as degrading under UV light and does not discuss UV for PETG; Prusament PETG is described as suitable for indoor and outdoor use. For years of sun, ASA is the usual answer (see UV-resistant outdoor prints).
- Water and humidity: Prusa calls PETG water and humidity resistant and notes its good layer adhesion suits waterproof parts. PLA is not described that way.
- Food contact: Prusa’s PLA and PETG articles both say the material itself can be considered food-safe but recommend against printing dishes or food containers, because the grooves between layers can harbour bacteria. A sealed coating and a stainless-steel nozzle are their suggested mitigation. Check the filament maker’s own statement; colourants and additives differ per spool.
Which one for which part
| Part | Pick | Reason |
|---|---|---|
| Display model, miniature, prototype | PLA | Stiff, clean detail, easy to print |
| Jig, template, gauge | PLA | Highest stiffness of the two (3,427 vs 2,117 MPa) |
| Phone stand, desk organiser | PLA | No heat or flex loads; cheapest to get right |
| Clip, hinge or snap-fit that flexes | PETG | Higher elongation, bends before it breaks |
| Enclosure near a heater or PSU | PETG | Glass transition 81 °C vs 61 °C |
| Garden or bathroom bracket, planter | PETG | Moisture resistant; better outdoors than PLA, ASA for long UV exposure |
| Part left in a car or in sun | PETG or ASA | PLA deforms above about 60 °C |
Common mistakes when choosing
- Judging by strength alone. The XY tensile numbers are nearly the same; heat and flex decide.
- Printing PETG on a smooth PEI sheet without a glue stick. Prusa warns that adhesion can be too strong and damage the sheet.
- Running PETG with the fan at 100%. Polymaker recommends off to 20%, and Prusa suggests off for the first layers, then about half power; more cooling lowers layer bonding.
- Choosing PLA because it is “biodegradable”. Prusa notes it needs industrial composting above 80 °C, not a garden heap.
- Ignoring drying. Polymaker lists a drying step for both (55 °C for 6 h for PLA, 65 °C for 6 h for PETG). Stringing that persists after retraction tuning is worth a test with a dried spool.
Frequently asked questions
Is PETG stronger than PLA?
Not in a simple tensile test: Polymaker lists 52.3 MPa for PLA and 50.8 MPa for PETG along the layers. PETG is better where heat and flexing matter, because it softens at a higher temperature and stretches further before breaking. PLA is stiffer.
Is PETG harder to print than PLA?
Usually yes, a little. PETG needs a hotter nozzle and bed, less cooling, and more care with stringing and bed adhesion, and it can fuse to smooth PEI sheets. PLA prints at lower temperatures and tolerates a wider range of settings.
Which is better outdoors, PLA or PETG?
PETG. Prusa lists PLA as degrading under UV light, and Prusament PETG is described as suitable for outdoor use. For parts that stay in direct sun for years, ASA is the usual upgrade.
Are PLA and PETG food safe?
Prusa says both materials can be considered food-safe in themselves but recommends against dishes and food containers, because layer grooves can harbour bacteria. If you need food contact, rely on the filament maker’s own statement and consider a food-safe sealing coating.
