Since you can't try them on, use these strategies to ensure a perfect fit: Go to product viewer dialog for this item.
The most critical factor in a winter sock is the fabric. Unlike cheap cotton, which holds moisture and makes your feet feel like blocks of ice, you want materials that manage both heat and sweat.
Darn Tough Men's Mountaineering Micro Crew Heavyweight Hiking Socks
Don't just buy the thickest pair you see. Your activity level dictates the "weight" of the sock you need: