What height sock do I need for cross-country skiing?

It depends on your boot height. Most Nordic boots have a lower cuff than alpine boots, so mid-calf socks often provide adequate coverage. However, over-the-calf socks are also common and preferred by skiers who want full lower-leg warmth and compression. The key rule is that the sock must extend above the boot cuff — any skin contact with the boot edge will cause chafing. Check where your boot cuff sits on your leg and choose accordingly.