Wettswil am Albis (sometimes written Wettswill a.A.) has an area of . Of this area, 42.3% is used for agricultural purposes, while 23.7% is forested. Of the rest of the land, 30.9% is settled (buildings or roads) and the remainder (3.2%) is non-productive (rivers, glaciers or mountains). The term am Albis in the name refers to the chain of hills in the area.