"Outdoor-rated" hides three different failure modes
UV embrittlement, water ingress, and thermal cycling stress a printed part in different ways and at different rates, and a material that resists one does not automatically resist the others. PLA embrittles under UV within months outdoors regardless of how dry it stays; TPU tolerates wetting well but is not immune to UV over years; a material can survive both and still crack from repeated expansion and contraction if it is not built for thermal cycling. Collapsing all three into one "outdoor: yes/no" answer hides which specific risk actually applies to your part.
How the screen works
Each material carries separate qualitative ratings for UV tolerance, wetting tolerance, and thermal-cycling tolerance. Your stated sun exposure and wetting level are compared against those specific ratings rather than one blended score, and each concern that exceeds the material's tolerance is named individually in the result, so you know exactly which risk (not just "outdoor risk" in the abstract) applies.
Worked example
PETG in partial sun with occasional rain and real thermal cycling: PETG's moderate UV tolerance is a reasonable match for partial (not full) sun, and its wetting tolerance handles occasional rain fine, but the result still names UV as the concern to watch if sun exposure increases, and recommends ASA specifically (not generic ABS) as the stronger outdoor-focused alternative.
A common mistake
A frequent error is choosing generic "ABS" branding for an outdoor part expecting UV resistance, when standard ABS actually performs poorly outdoors compared to its UV-stabilized sibling, ASA. The two share a family name in casual conversation but behave very differently in sunlight; always confirm you are buying the specific ASA-grade filament, not generic ABS, for genuine outdoor use.
Limitations
These are general family-level ratings for planning, not a weathering-test result for your specific brand, color, or additive package of filament. Real outdoor durability also depends on print quality and infill density in ways this screen cannot see, and every material degrades gradually with years of real-world exposure regardless of its rating here.