PETG
PETG (polyethylene terephthalate glycol) is a tough, slightly flexible thermoplastic used in FDM 3D printing. It prints almost as easily as PLA but handles more heat, impact, and moisture, which makes it a default choice for functional prototypes.
Updated 28 Sep 2026 · 4 min read · By Wyntek
What PETG is
PETG is a copolyester: the same PET used in drink bottles, with part of its ethylene glycol replaced by a second glycol during manufacture. That change stops the plastic from crystallising. The result is a clear, amorphous material that is less brittle than PET and prints at lower temperatures.
Because it is amorphous, PETG has no sharp melting point. It softens gradually as it warms past its glass transition at roughly 77 to 80 °C, which is why printed PETG parts are usually rated for use below about 75 °C.
Typical properties
| Property | Typical value | What it means for a part |
|---|---|---|
| Tensile strength, in-plane | 46 to 50 MPa at yield | Strong enough for brackets, clips, and housings |
| Tensile strength, across layers | About 19 MPa at break | Layer bonds are the weak direction, so orient loads along the layers |
| Stiffness (tensile modulus) | About 1.7 to 1.9 GPa | More flexible than PLA, so it bends before it breaks |
| Heat deflection at 0.455 MPa | About 76 °C (169 °F) | Survives warm spots that deform PLA |
| Density | 1.27 g/cm³ | Close to PLA, so parts weigh about the same |
| Moisture | Absorbs a little from the air | Dry filament prints cleanly; damp filament strings and bubbles |
The strength figures come from printed test bars at 100% infill. A real part with walls and partial infill will be weaker, and the gap between in-plane and across-layer strength is the number to remember: loads that try to peel layers apart fail first.
Where PETG works well
- Functional prototypes that take load or knocks. PETG yields and bends before it snaps, where PLA tends to crack.
- Parts that get warm: inside a car, next to electronics, or outdoors in the sun, up to about 75 °C.
- Parts exposed to water, humidity, alcohols, and weak acids or bases.
- Enclosures, brackets, mounts, jigs, fixtures, and cable guides.
- Snap fits and living features that need a little give.
Limits to design around
- Stringing. PETG tends to leave fine hairs and small blobs on travel moves, so it is not the first choice for crisp cosmetic surfaces.
- Bridges and overhangs sag more than in PLA, and supports bond firmly, which makes them harder to remove cleanly.
- Printed PETG is not a food-safe part. Layer lines trap bacteria, and material makers such as Ultimaker list food contact as unsuitable.
- Heat above roughly 75 °C softens it. For hotter parts, ABS holds its shape to around 85 to 95 °C, and machined aluminium goes far higher.
PETG compared with PLA, ABS, and nylon
| Material | Heat resistance | Toughness | Printing | Typical use |
|---|---|---|---|---|
| PLA | About 55 °C | Stiff but brittle | Easiest | Form and fit checks |
| PETG | About 75 °C | Tough, bends before breaking | Easy | Functional prototypes |
| ABS | About 85 to 95 °C | Tough | Harder, prone to warping | Hot environments |
| Nylon | Varies by grade | Very tough, flexes without breaking | Hardest, must stay dry | Clips, hinges, wear parts |
Designing parts for PETG
- Orient the part so the main load runs along the layers. Printed PETG is less than half as strong across layers as it is within them.
- Give load-bearing walls at least 1.2 mm, which is three perimeters on a standard 0.4 mm nozzle.
- Start sliding fits at about 0.3 mm clearance per side, then adjust after a test print.
- Replace flat overhangs with 45 degree chamfers so the part needs fewer supports.
- Round internal corners. A small fillet spreads stress and suits PETG's tendency to bend rather than crack.
At Wyntek
PETG is on every Wyntek plan, including the free tier. Upload your file, choose FDM and PETG, and you see the price in US dollars before you submit. Every part is scanned before it ships.
Print a part in PETG