Detroit is 48% larger than Seattle.
Area: 259 km2 calculated
Seattle is a coastal seaport city and the seat of King County, in the U.S. state of Washington. With an estimated 652,405 residents as of 2013, Seattle is the largest city in the Pacific Northwest region of North America and the fastest-growing major city in the United States. Wikipedia
Area: 383 km2 calculated
Detroit is the most populous city in the U.S. state of Michigan and the largest city on the United States-Canada border. It is the seat of Wayne County, the most populous county in the state. Wikipedia