Conversion formula

The conversion factor from feet per second to miles per hour is 0.68181818181818, which means that 1 foot per second is equal to 0.68181818181818 miles per hour:

1 ft/s = 0.68181818181818 mph

To convert 397.9 feet per second into miles per hour we have to multiply 397.9 by the conversion factor in order to get the velocity amount from feet per second to miles per hour. We can also form a simple proportion to calculate the result:

1 ft/s → 0.68181818181818 mph

397.9 ft/s → V_(mph)

Solve the above proportion to obtain the velocity V in miles per hour:

V_(mph) = 397.9 ft/s × 0.68181818181818 mph

V_(mph) = 271.29545454545 mph

The final result is:

397.9 ft/s → 271.29545454545 mph

We conclude that 397.9 feet per second is equivalent to 271.29545454545 miles per hour:

397.9 feet per second = 271.29545454545 miles per hour

Alternative conversion

We can also convert by utilizing the inverse value of the conversion factor. In this case 1 mile per hour is equal to 0.003686018262545 × 397.9 feet per second.

Another way is saying that 397.9 feet per second is equal to 1 ÷ 0.003686018262545 miles per hour.

Approximate result

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

397.9 ft/s ≅ 271.295 mph

An alternative is also that one mile per hour is approximately zero point zero zero four times three hundred ninety-seven point nine feet per second.

Conversion table

feet per second to miles per hour chart

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