Ideally, you’ll have a fresh pair of socks for every day that you spend on the snow. But if travel limits your access to laundry, or if you ski every day and don’t want to spend $300 dollars just on socks, you can stretch 2-3 days out of a pair before washing. A weeklong ski trip could be dependably covered by 3-4 pairs of socks. It’s definitely worth noting merino wool socks will be a little more resistant to odor than cheaper synthetics.