PETG (Polyethylene Terephthalate Glycol)
polymeramorphous/semi-crystalline copolyester thermoplastic
Polyethylene terephthalate glycolPET-GPETG+eSUN PETGPrusament PETGColorFabb PETGGlycol-modified PET
Mechanical & thermal properties — 2 conditions
| Property | FDM as-built (XY) | FDM as-built (Z — upright) |
|---|---|---|
| Elastic modulus | 2–3 GPa | — |
| Ultimate tensile strength | 44–56 MPa | 25–38 MPa |
| Elongation at break | 20.0–50.0 % | 5.0–18.0 % |
| Density | 1.25–1.29 g/cm³ | — |
| Glass transition (Tg) | 75–85 °C | — |
| As-built surface Ra | 7.0–18.0 µm | — |
Values shown as min–max where a spread is reported, otherwise as typical ± unit. Ranges reflect inter-source variation, not single-sample scatter. All values are for AM-processed specimens unless noted.
Engineering considerations
- Material selection vs PLA: choose PETG over PLA when any of these apply: (1) temperatures above 50°C, (2) impact or dynamic loading, (3) snap-fits or clips, (4) chemical exposure, (5) food/water contact. Use PLA when stiffness is paramount and temperature is controlled.
- Material selection vs ABS: choose PETG over ABS when: (1) no heated chamber available, (2) food contact required, (3) odour is a concern, (4) chemical resistance needed. Use ABS when: (1) acetone smoothing is needed, (2) maximum heat resistance within FDM polymers is required, (3) painting/plating finishes are planned.
- Moisture management: dry PETG filament at 65–70°C for 4–8h before printing if stored without desiccant for more than a few days. Wet PETG shows stringing, blobbing, and reduced mechanical properties. Vacuum-seal with silica gel for long-term storage.
- Print settings sensitivity: PETG is highly print-settings-sensitive. UTS can vary ±20% with nozzle temperature and speed changes. Run characterisation samples before structural applications. Higher nozzle temperature (245–250°C) generally improves layer adhesion and Z-direction strength.
- Wall design: PETG's ductility means thick walls increase toughness disproportionately. For impact-prone enclosures, prefer 2–3 wall perimeters over high infill. The outer walls carry most impact load.
- Chemical resistance caveat: while PETG resists dilute acids and bases well, it is attacked by concentrated acids and esters. Verify chemical compatibility with specific reagents for laboratory or industrial applications before deployment.
- Transparency: for optical parts, use transparent PETG with 0% infill (single-wall vase mode) or near-100% infill and minimal layers. Annealing can increase haze. XY-oriented specimens have better clarity than Z-oriented due to layer line visibility.
Advantages
- Significantly better impact resistance than PLA: ductile failure mode (20–50% elongation vs. PLA 3–6%) means PETG bends rather than shatters
- Higher temperature resistance than PLA: HDT ~72°C vs ~55°C — survives hot cars and warm environments
- Better chemical resistance than PLA and ABS: resistant to dilute acids, bases, and many alcohols. Not attacked by water-based solutions
- Food-safe in appropriate grades: PETG is the same polymer family as PET used in food bottles — food-contact certified grades widely available
- Good optical clarity: PETG can be printed in transparent grades with good light transmission — useful for light diffusers and display parts
- Semi-flexible without being rubbery: slight flex on impact prevents catastrophic failure while maintaining dimensional stability
- Easier to print than ABS: no heated chamber required, minimal warping, good bed adhesion, lower odour
- Recyclable: PETG (like PET) can be recycled via standard plastics recycling streams
Limitations
- No solvent smoothing: unlike ABS, PETG cannot be smoothed with acetone. Surface finishing requires sanding, priming, or chemical treatments (specific to grade). Finish quality is harder to achieve than with ABS
- Lower stiffness than PLA (2.2 vs 3.5 GPa): PETG parts flex slightly under load — not ideal for high-rigidity applications
- Moisture sensitivity: PETG is hygroscopic. Wet filament causes stringing, bubbles, and poor surface quality. Dry at 65–70°C for 4–8h if stored unsealed
- Stringing tendency: PETG has higher tendency to string between features compared to PLA — requires careful retraction settings
- Not suitable for prolonged UV exposure without UV-stabilised grades: standard PETG yellows over time outdoors
- Over-adhesion to print beds: PETG sticks extremely well to glass and smooth surfaces — use PEI, glue stick, or release agent to allow part removal without damage
- Density penalty: heavier than ABS (1.27 vs 1.05 g/cm³) for equivalent geometry — matters in weight-critical applications
Typical applications
Mechanical parts requiring toughness and some heat resistance: brackets, mounts, enclosuresWater bottles, food contact containers, and fluid handling components (food-safe grades)Medical device housings and instrument casings requiring chemical resistanceElectronic enclosures where occasional heat exposure is possibleSnap-fit and clip mechanisms where ductility prevents brittle fractureTransparent or translucent parts — PETG has excellent optical clarityAquarium equipment and wet-environment applications (better hydrolysis resistance than PLA)Consumer product casings and display componentsProtective covers and guards for machinery
Industries
consumerindustrialmedicalelectronics
Standards & certifications
iso-527-3-2018established
Tensile testing of plastic specimens from FDM PETG parts
consumerindustrial
ISO 527-2 Type 1B more commonly used for FDM test coupons. PETG food-contact grades may meet EU Regulation (EC) No 10/2011 for plastic materials in contact with food.
Compatible AM processes (1)
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Related calculators
Extrusion WidthActual extrusion width from nozzle diameter, layer height, and flow rate multiplier. Wall perimeter count from nominal thickness. FFF/FDM design rule compliance check.RoughnessTheoretical Ra and Rz from layer thickness and surface angle (staircase effect). Upward, downward, and vertical faces. LPBF, SLS, FDM, SLA, DED. Per Grimm et al.Dimensional AccuracyExpected dimensional deviation (mean bias ± 1σ) for XY and Z axes by process, material class, and geometry type. Based on aggregated published accuracy datasets. Answers: what tolerance can I realistically hold?Cost-Per-Part EstimatorMachine hourly + material + labor + post-processing → unit cost with margin. Currency-agnostic.
Last reviewed: 2026-05-13 · v1 · Sources: esun-petg-datasheet-2022, peng-2018-petg-fdm, srinivasan-2020-petg-mech, iso-527-3-2018
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