Convert from square chain [Gunter, survey] to square mile

Unit Definition (square chain [Gunter, survey])
The square chain [Gunter, survey] is a traditional unit of area in English surveying, defined to be the area of a square whose side equals Gunter's chain (4 rods or 22 yards). Thus the square chain equals 16 square rods, 484 square yards, 4356 square feet, or exactly 0.1 acre.

Unit Definition (square mile)
The square mile is a traditional unit of area. One square mile is equal to 640 acres, 3 097 600 square yards, 258.9988 hectares, or 2.589 988 square kilometers.