PETG Temperature Resistance: How Hot Can It Get?

PETG is the default material for functional FDM parts, and temperature is the limit people hit first. The short answer is that PETG holds its shape to roughly 70 to 75 degrees Celsius without load, and noticeably less when the part is carrying something.

What the datasheet number actually means

Datasheets list a glass transition temperature of about 80 to 85 degrees Celsius for PETG, and a heat deflection temperature of roughly 70 degrees at 0.45 MPa. Neither number is a service temperature. The glass transition is the point where the polymer chains start moving freely, which is well past the point where a part loses its shape under any real stress.

For design purposes we use 60 degrees as the safe continuous limit for loaded PETG parts, and 70 degrees for unloaded parts that only need to keep their shape.

Load changes everything

A PETG bracket sitting on a shelf at 70 degrees will be fine. The same bracket holding 5 kilograms at 60 degrees will slowly sag. This is creep, and it accelerates sharply as you approach the glass transition. A part that survives a one hour test at temperature can still deform after a week at the same temperature.

If your part carries load at elevated temperature, test at temperature and for time, not just at room temperature.

Common cases where PETG is not enough

• Dashboard or rear shelf of a parked car in summer: interior surfaces regularly exceed 80 degrees. PETG deforms.
• Directly next to a power supply, motor housing or LED driver: local air temperature can sit above 70 degrees continuously.
• Parts that get cleaned in a dishwasher or with steam: the cycle temperature alone is enough to distort thin walls.
• Enclosures in direct sun with a dark colour: surface temperature can be 30 degrees above ambient.
• Any part near a heated bed, hot end or heating element.

What to use above PETG

• ABS: usable to roughly 90 degrees, tougher than PETG, good for enclosures and automotive interior parts.
• ASA: similar temperature behaviour to ABS with far better UV resistance. The right choice for outdoor and sun exposed parts.
• PC: usable to roughly 110 to 120 degrees, high stiffness and impact strength. PC FR adds UL94 flame retardancy for electrical housings.
• PA12 and PA6-CF: good thermal and chemical resistance with high toughness. PA6-CF holds structural load well above 100 degrees.
• PPS and PEEK class materials: only when the application genuinely requires it, since cost and lead time rise sharply.

Can you make PETG more heat resistant?

Not meaningfully. Unlike PLA, PETG does not gain a useful amount of heat resistance from annealing, and annealing introduces shrinkage that ruins tolerances. Thicker walls and more perimeters help a part resist deformation for longer, but they do not raise the material limit. If the temperature is the problem, change the material.

How to specify this on an order

Give the supplier the maximum temperature, whether the part is loaded at that temperature, and how long it stays there. Those three values are enough to choose between PETG, ABS, ASA, PC and PA. A part described only as 'gets warm' usually ends up in the wrong material.

We print PETG and higher temperature engineering materials in Germany and check the thermal requirement before production, not after. Upload your file and tell us the operating temperature.