Conversion formula

The conversion factor from feet to miles is 0.00018939393939394, which means that 1 foot is equal to 0.00018939393939394 miles:

1 ft = 0.00018939393939394 mi

To convert 21 feet into miles we have to multiply 21 by the conversion factor in order to get the length amount from feet to miles. We can also form a simple proportion to calculate the result:

1 ft → 0.00018939393939394 mi

21 ft → L_(mi)

Solve the above proportion to obtain the length L in miles:

L_(mi) = 21 ft × 0.00018939393939394 mi

L_(mi) = 0.0039772727272727 mi

The final result is:

21 ft → 0.0039772727272727 mi

We conclude that 21 feet is equivalent to 0.0039772727272727 miles:

21 feet = 0.0039772727272727 miles

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 mile is equal to 251.42857142857 × 21 feet.

Another way is saying that 21 feet is equal to 1 ÷ 251.42857142857 miles.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that twenty-one feet is approximately zero point zero zero four miles:

21 ft ≅ 0.004 mi

An alternative is also that one mile is approximately two hundred fifty-one point four two nine times twenty-one feet.

Conversion table

feet to miles chart

For quick reference purposes, below is the conversion table you can use to convert from feet to miles