Guam is approximately 210 to 212 square miles (about 544 to 549 square kilometers) in total land area. It measures roughly 30 miles (48 kilometers) in length and varies from 4 to 12 miles (6 to 19 kilometers) in width. The island's coastline stretches about 125 to 129 kilometers (80 miles). It is the largest island in Micronesia and the southernmost in the Mariana Islands.