When you're packing for a long trip it's sometimes hard to determine how many pairs of underwear you need. This chart helps you determine the perfect amount by comparing how many pairs, how many days you're away, and how many washes will be required.
The chart, courtesy of Reed Kennedy at weblog Pack Like a Nerd, helps you find that sweet spot of perfect pair packing. The gold numbers on the chart indicate a "perfect run", or a trip that has you returning home with no extra clean underwear while doing the minimum possible washes on the trip. Be aware, that Kennedy makes two assumptions for the chart: first, that you'll be wearing underwear when you wash, and second, that you'll do the wash while wearing your last pair of undies. For more information — and a graph that shows you how many clean pairs you'll have when you return instead — check the link below.