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 991 feet per second into miles per hour we have to multiply 991 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

991 ft/s → V_(mph)

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

V_(mph) = 991 ft/s × 0.68181818181818 mph

V_(mph) = 675.68181818182 mph

The final result is:

991 ft/s → 675.68181818182 mph

We conclude that 991 feet per second is equivalent to 675.68181818182 miles per hour:

991 feet per second = 675.68181818182 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 0.0014799865455769 × 991 feet per second.

Another way is saying that 991 feet per second is equal to 1 ÷ 0.0014799865455769 miles per hour.

Approximate result

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

991 ft/s ≅ 675.682 mph

An alternative is also that one mile per hour is approximately zero point zero zero one times nine hundred ninety-one 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