MPH to FPS: Mentally Converting Miles Per Hour to Feet Per Second
The Quick, Easy Answer.
Divide MPH by 2, then multiply by 3 to find FPS.
Converting MPH to FPS? The Quick and Easy Method
Divide MilesperHour by 2, then multiply by 3 to find FeetperSecond.
This is the easy, quick math way, but it gives a fairly accurate answer. Your answer will be accurate to within 5%. As an example, 100 MPH converts to 150 FPS. If you did the more complicated math calculation (see below), you would get 147 FPS.
Easy Conversion from MPH to FPS
MPH
 FPS


10
 15

15
 22.5

20
 30

25
 37.5

30
 45

35
 52.5

40
 60

45
 67.5

50
 75

55
 82.5

60
 90

65
 97.5

70
 105

80
 120

90
 135

100
 150

120
 180

140
 210

160
 240

The Harder (and More Accurate) Answer
1. First, you must convert MPH to MPM (minute) by dividing MPH by 60.
2. Second, convert miles to feet. There are 5,280 feet in one mile, so multiply MPM by 5,280 to get FPM.
3. Convert FPM to FPS by dividing by 60.
Examples of the Longhand Math Converting MilesPerHour (MPH) to FeetPerSecond (FPS)
Math Example One
You're going 25 mph. How many feet is that per second?
Conversion from mph to fps is as follows: If we divide by 60, we get milesperminute:
25/60 = .416667
For accuracy's sake, now is a good time to convert miles to feet. There are 5,280 feet in a mile so we multiply mpm times 5,280 to get feetperminute:
.416667 x 5280 = ~2199.99 feetperminute [note: "~" means approximate]
To convert from feetperminute to feetpersecond, we divide the answer by 60:
2199.99/60 = ~36.667 feetper second.
This answer is within 5% of the one you get doing the easy math, which says 25 mph equals 37.5 fps.
Math Example Two
65 mph. How many feet per second?
Conversion from mph to fps is as follows: If we divide by 60, we get milesperminute.
65/60 = 1.0843333333333
This makes sense. After all, 60 miles an hour is obviously equal to a mileaminute.
For accuracy's sake, now is a good time to convert miles to feet. There are 5,280 feet in a mile, so we multiply the milesperminute times 5,280 to get feetperminute:
1.0843333333333 x 5280 = ~5725.28 feetperminute [note: "~" means approximate]
To convert from feetperminute to feetpersecond, we divide the answer by 60:
5725.28/60 = ~95.421 feetper second.
This coincides within 5% of the table above, which says 65 mph equals 97.5 fps.
Math Example Three
120 mph is how many feet per second? Conversion from mph to fps is as follows. If we divide by 60, we get milesperminute:
120/60 = 2.000
This makes sense. After all, 60 miles an hour is obviously equal to a mileaminute. So 120 mph would be 2milesaminute.
For accuracy's sake, now is a good time to convert miles to feet. There are 5,280 feet in a mile, so we multiply the milesperminute times 5,280 to get feetperminute:
2 x 5280 = ~10560 feetperminute [note: "~" means approximate]
To convert from feetperminute to feetpersecond, we divide the answer by 60:
10560/60 = ~176 feetper second.
This number is within 5% of the table above which says 120 mph equals 180 fps.
FPS to MPH
Quick way to find the reverse, i.e. convert from fps to mph:
Divide FPS by 3 and then multiply by 2 to get MPH
Some Examples:
10 fps = 6.67 mph
25 fps = 16.67 mph
50 fps = 33.33 mph
100 fps = 66.67 mph
150 fps = 100 mph
Again, the "within 5% accuracy" caveat applies.
Doing 20 MilesPerHour? That's 30 FeetPerSecond
It is hoped this math trick and ruleofthumb will serve you well, especially on those rain and ice slicked roads.
The Most Ridiculous Car Chase Ever
Comments 2 comments
Aahhh very useful indeed and thank you for sharing.
Here's to so many more for us both to share on here.
Eddy.
MPH to KNOTS is: Take 10%, halve that and add the two, then subtract from MPH. So 60MPH is 6+3 subtracted from 60...51KTS.
then backwards:
A plane going 400KTs is going (40+20) 460MPH...