Best filament for outdoor use
Outdoors, a print faces three enemies at once: ultraviolet light, heat, and moisture. Most filaments fail on at least one. If a part will live in the sun, on a car, or in the garden, the material choice matters more than any print setting. For most people the answer is ASA, but PETG earns a place and PLA does not.
What actually breaks a print outdoors
Three failure modes matter. UV light breaks down many plastics over months, causing yellowing, chalking, and cracking. Heat is more immediate: a dark part on a dashboard or in direct sun can pass the temperature at which the plastic softens and sags, well below the air temperature. Moisture and thermal cycling, the daily swing from hot day to cold night, then work cracks into any part already weakened by the first two. The right outdoor material resists all three, not just one.
The one thing not to get wrong
Heat resistance and UV resistance are separate problems. A material can shrug off sunlight and still sag in a hot car, or survive heat and still yellow and crack in UV. Outdoor parts need both.
ASA: the default outdoor choice
ASA is the material engineered for this job. It is about as strong as ABS but adds real UV stability, so it resists the yellowing, fading, warping, and cracking that sunlight causes in other plastics, and it keeps its properties under prolonged exposure. That combination of strength, heat tolerance, and weather resistance is why ASA is the standard recommendation for anything that lives outside. The tradeoff is that it prints like ABS: it wants a high nozzle temperature and an enclosure, and it can warp and emit fumes without one. If you can print ABS, you can print ASA, and outdoors ASA is the better material.
PETG: good enough for moderate exposure
PETG is the practical middle ground. It resists water well and tolerates UV to a degree, and it prints far more easily than ASA with no enclosure required. The limit is time and heat: prolonged sun will gradually degrade PETG, and it softens at a lower temperature than ASA, so a PETG part can sag in a hot enclosed space like a parked car. For a planter, a bracket under an eave, or anything with partial shade and moderate sun, PETG is often good enough and much easier to print. For full-sun, high-heat, multi-year parts, step up to ASA.
ABS and PLA: what to avoid
ABS is strong and heat tolerant but only moderately UV resistant, so untreated ABS is not a good long-term outdoor material. It yellows and grows brittle in sunlight and warps badly while printing. ASA exists specifically to fix ABS outdoors, so if you were reaching for ABS for an outdoor part, reach for ASA instead. ABS outside really only makes sense with a protective coating.
PLA is the wrong choice outdoors, full stop. It softens at a low temperature, so it can sag in a hot car or in direct summer sun, and it grows brittle and degrades with sustained UV and moisture. PLA is a fantastic indoor material and a poor outdoor one. No print setting fixes this; it is the material.
Quick pick
Full sun, heat, and years of service: ASA. Moderate sun, easy printing, water resistance: PETG. Strong but shaded or coated: ABS is acceptable. Anything load-bearing in real weather: not PLA. Polycarbonate is stronger and more heat resistant still, but it also yellows in UV without a coating, so it is not an automatic outdoor upgrade.
Compare current pricing on the tracker: the ASA listings, the PETG listings, and the ABS listings put price per kg side by side.
For settings and the deeper tradeoffs, the ABS and ASA guide covers ventilation and warping, and the PETG guide covers where PETG fits.