Fort Worth, Texas is 3.9 times larger than Amarillo, Texas.
Area: 257 km2 calculated
Amarillo is the fourteenth most populous city in the state of Texas, also the largest City in the Texas Panhandle, and the seat of Potter County. A portion of the city extends into Randall County. The population was 190,695 at the 2010 census. Wikipedia
Area: 1,011 km2 calculated
Fort Worth is the 17th-largest city in the United States of America and the fifth-largest city in the state of Texas. Wikipedia