Conversion formula

The conversion factor from miles per hour to feet per second is 1.4666666666667, which means that 1 mile per hour is equal to 1.4666666666667 feet per second:

1 mph = 1.4666666666667 ft/s

To convert 399 miles per hour into feet per second we have to multiply 399 by the conversion factor in order to get the velocity amount from miles per hour to feet per second. We can also form a simple proportion to calculate the result:

1 mph → 1.4666666666667 ft/s

399 mph → V_(ft/s)

Solve the above proportion to obtain the velocity V in feet per second:

V_(ft/s) = 399 mph × 1.4666666666667 ft/s

V_(ft/s) = 585.2 ft/s

The final result is:

399 mph → 585.2 ft/s

We conclude that 399 miles per hour is equivalent to 585.2 feet per second:

399 miles per hour = 585.2 feet per second

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 foot per second is equal to 0.0017088174982912 × 399 miles per hour.

Another way is saying that 399 miles per hour is equal to 1 ÷ 0.0017088174982912 feet per second.

Approximate result

For practical purposes we can round our final result to an approximate numerical value. We can say that three hundred ninety-nine miles per hour is approximately five hundred eighty-five point two feet per second:

399 mph ≅ 585.2 ft/s

An alternative is also that one foot per second is approximately zero point zero zero two times three hundred ninety-nine miles per hour.

Conversion table

miles per hour to feet per second chart

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