Miles to feet (mi to ft)

One mile is exactly 5,280 feet. That ratio belongs to the customary system itself and is much older than any link to metric: the 1959 international yard and pound agreement later fixed the yard and the pound against the meter and the kilogram, but it left the ratios between customary units (feet to the yard, ounces to the pound, cups to the gallon) exactly as they were.

Worked through: 2 mi x 5,280 = 10,560 ft.

Going the other way, one foot is 0.0001893939 miles.

To convert without a calculator, multiply by 5,280. Rounding that to 5,300 is within 0.38% for most purposes.

5,280 feet to the mile, which looks arbitrary and is: the mile came from the Roman mille passus of a thousand double paces, and was later fixed at 8 furlongs of 660 feet each. The furlong (a furrow long) is the reason for the odd number.

Precision is worth matching to the input. A measurement given as 0.25 mi carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.