Most quality ski socks fall in the 40–70% merino range, which hits the sweet spot between natural performance and long-term durability. Merino wool regulates temperature, wicks moisture, and fights odor — but it needs help from other fibers to hold up inside a stiff ski boot.
Below 30% merino, you start losing those natural benefits, and the sock behaves more like a synthetic. Above 70%, the sock may feel great initially but can wear out faster and lose its shape over time, since pure wool lacks the stretch and resilience needed for a snug boot fit.
The remaining content is typically nylon (adds durability and abrasion resistance) and a small percentage of elastane or spandex (provides stretch so the sock stays up and retains its shape). When comparing socks, don't just look for "merino" on the label — check the actual percentage so you know what you're getting.