Convert ft/s to km/h feet per second ↔ kilometres per hour Free Online Secure
Type a value in feet per second and read it in kilometres per hour at once. The factor is exact by definition, the arithmetic happens in your browser, and nothing is sent anywhere.
Nothing uploaded
Convert from feet per second
Convert to kilometres per hour
Common values — Convert ft/s to km/h (feet per second ↔ kilometres per hour)
| ft/s | km/h |
|---|---|
| 1 | 1.09728 |
| 2 | 2.19456 |
| 3 | 3.29184 |
| 5 | 5.4864 |
| 10 | 10.9728 |
| 20 | 21.9456 |
| 50 | 54.864 |
| 100 | 109.728 |
Where these units come from
Speed has no unit of its own: it is a length divided by a time, so every trade simply kept the length it was already using. That is why the same motion is 100 km/h on a European road sign, 62 mph on an American one and 27.8 m/s in a physics problem. The knot is the oldest of them and the most literal: sailors paid out a line with knots tied at even spacing and counted how many ran through their fingers while a sand glass emptied, so the speed was read off in knots. One knot is one nautical mile per hour, and a nautical mile is a minute of latitude — which is why ships and aircraft still use it. The speed of light is the odd one out: since 1983 it is not measured but fixed at exactly 299,792,458 m/s, because the metre is now defined from it.
Where you meet them
Kilometres and miles per hour live on speedometers and road signs, metres per second in physics, engineering and wind reports, feet per second in ballistics and in American machine shops. Knots carry shipping, aviation and marine weather, and Mach numbers appear wherever an aircraft is fast enough for the air's own stiffness to matter. The speed of light turns up less in daily life than in distances: a light year is simply how far it gets in one.
Questions people ask
Is Mach 1 a fixed speed?
No. Mach is a ratio to the speed of sound in the surrounding air, and sound travels more slowly in colder air. This page uses the standard sea-level figure, 340.294 m/s, so Mach 1 here is about 1225 km/h. At the altitude airliners cruise at, the air is some 50 degrees colder and the same Mach 1 is roughly a tenth slower. An aircraft can therefore hold a constant Mach number while its speed over the ground changes.
Why do ships and aircraft use knots rather than km/h?
Because a nautical mile is one minute of arc of latitude. A vessel making one knot covers one minute of latitude in an hour, so speed, time and position on a chart fit together without conversion. The same reasoning kept the nautical mile at exactly 1852 metres rather than rounding it to something tidier.
Is the answer exact?
Where both units are defined in terms of one another by whole numbers, yes — the page says so above the figure, and the only rounding is in how many digits are shown. Where the ratio has no finite decimal, the page shows twelve significant digits and says the relation is approximate rather than pretending otherwise.
Does anything I type leave my device?
No. The arithmetic runs in your browser; nothing is uploaded and there is no server to upload it to. Load the page once and it keeps working with the network switched off.
Feet per second to kilometres per hour: reading American sports and science in the speed the rest of the world uses
Baseball radar guns, hockey shot trackers, ballistics tables and a long line of American physics problems give speed in feet per second, while a fan in Europe, Asia or Africa follows the same game in kilometres per hour. A pitcher throwing 146.7 ft/s means little to most of them, but 161 km/h means something at once. To convert ft/s to km/h, multiply by 1.0973: 100 ft/s is 109.7 km/h, 200 ft/s is 219.5 km/h and 300 ft/s is 329.2 km/h. The calculator above does it as you type, and the sections below walk through what the numbers look like in sport, in classrooms and in daily life.
The page covers the rule with worked examples, a profile of each unit, a comparison and many practical cases, followed by the usual mistakes. The calculation runs in your browser and the figures you type are not sent anywhere. For official records, always refer to the governing body or the original standard.
How to convert ft/s to km/h: multiply by 1.0973
The rule
A foot is exactly 0.3048 metres and an hour has 3,600 seconds, so one foot per second equals 0.3048 × 3,600 = 1,097.28 metres per hour, which is 1.09728 km/h. To convert ft/s to km/h, multiply the value in ft/s by 1.0973. That makes 10 ft/s equal to 10.97 km/h, 66 ft/s equal to 72.4 km/h and 176 ft/s equal to 193.1 km/h. To go back, multiply km/h by 0.9113.
Worked examples
A pitch at 132 ft/s is 144.8 km/h. A fast-moving car at 88 ft/s travels at 96.6 km/h. A slap shot at 160 ft/s is 175.6 km/h, and a tennis serve at 240 ft/s is 263.3 km/h.
How accurate the factor is
The international foot is defined as exactly 0.3048 metres, so the multiplier is exact. If two answers differ, it is because they carry a different number of decimals.
A quick sanity test
The figure in km/h is about 10 per cent larger than the figure in ft/s. If a “convert ft/s to km/h” calculation left you with a smaller number than you started with, you used the factor from the opposite direction.
The foot per second
The unit of American mechanics and sport science
The foot per second is the speed unit of the US customary system. Physics textbooks, sports biomechanics papers and some radar and timing equipment report speed in it, because lengths on the field are in feet and times in seconds.
Where it appears
Textbooks, sport science papers, timing systems and accident reconstruction.
The kilometre per hour
The everyday unit of speed
The kilometre per hour is the usual unit for the speed of vehicles and, in most countries, of sporting balls as well. Road signs, speedometers, broadcast graphics and record books outside North America all use it.
Where it appears
Road signs, speedometers, sports broadcasts and record books.
Feet per second against kilometres per hour
One ft/s is 1.097 km/h, so the number in km/h is about a tenth larger. A speed of 50 ft/s is 54.9 km/h and one of 100 ft/s is 109.7 km/h. The two units describe the same motion, and only the size of the unit differs.
The conversion is exact, with no hidden rounding. The main trap is confusing ft/s with mph, which differ by almost 47 per cent.
Where the conversion shows up
Ball sports
A fastball of 100 mph is 146.7 ft/s, which is 161 km/h. A cricket fast bowler at 132 ft/s sends the ball at 144.8 km/h. A tennis serve of 240 ft/s is 263 km/h. A “convert ft/s to km/h” calculation puts all three on the scale you see on a broadcast.
Ice hockey and racquet sports
A hockey slap shot of 159.6 ft/s is 175 km/h. The record badminton smash of 565 km/h is 515 ft/s. Because the puck or shuttle is small and fast, the time to react is a fraction of a second, and the unit does not change that.
Physics lessons
In US high schools many problems begin with "a ball is thrown at 60 ft/s". Students from other countries convert the figure to 65.8 km/h or 18.3 m/s to build intuition before applying the equations.
Time to reach the plate
A baseball pitched at 134 ft/s, about 147 km/h, covers the 60.5 feet from mound to plate in 0.45 seconds. At 146.7 ft/s, 161 km/h, the flight takes 0.41 seconds. A batter has roughly a quarter of a second to judge and swing, which is why every extra 10 km/h counts.
Reporting to the right precision
A radar gun that resolves to 1 mph gives about 1.5 ft/s, or 1.6 km/h. When you convert ft/s to km/h from such data, quoting 144.8 km/h implies more precision than the instrument has. Write 145 km/h and keep the extra digits in the spreadsheet.
Landmarks to memorise
To convert ft/s to km/h by eye, remember that 10 ft/s is 11 km/h. 30 ft/s is 33 km/h. 44 ft/s is 48 km/h. 66 ft/s is 72 km/h. 88 ft/s is 97 km/h. 100 ft/s is 110 km/h. 150 ft/s is 165 km/h. With these seven values you can read most American speed figures at a glance.
Reference ladder
1 ft/s is 1.10 km/h. 5 ft/s is 5.49 km/h. 15 ft/s is 16.46 km/h. 25 ft/s is 27.43 km/h. 50 ft/s is 54.86 km/h. 120 ft/s is 131.67 km/h. 220 ft/s is 241.4 km/h. 300 ft/s is 329.2 km/h. A ladder like this is useful for quick checks.
Checking by reversing
To check a “convert ft/s to km/h” calculation result, multiply the answer by 0.9113. If 88 ft/s became 96.56 km/h, then 96.56 times 0.9113 returns 88. A second test is size: the number of km/h should be about a tenth larger than the number of ft/s.
Link to mph and m/s
One ft/s is 0.682 mph and 0.3048 m/s. To go from mph to ft/s, multiply by 1.4667, then by 1.0973 to reach km/h. The direct route from mph to km/h multiplies by 1.609. All three describe the same speed.
Kinetic energy of a baseball
A 145 gram baseball at 146.7 ft/s, which is 44.7 m/s or 161 km/h, carries about 145 J. At 120 ft/s, 131.7 km/h, it carries 97 J. Energy grows with the square of the speed, so a small error in the converted figure becomes a larger error in the energy.
A worked example
A skid mark of 100 feet on dry asphalt with a friction coefficient of 0.7 implies an initial speed of √(2 × 32.174 × 0.7 × 100) = 67.1 ft/s. To convert ft/s to km/h on that result, multiply by 1.0973 to get 73.6 km/h. Doing it in metric units, √(2 × 9.81 × 0.7 × 30.48) = 20.46 m/s, which is 73.6 km/h again.
Road speeds
US speed limits translate as follows: 25 mph is 36.7 ft/s or 40.2 km/h, 55 mph is 80.7 ft/s or 88.5 km/h, and 65 mph is 95.3 ft/s or 104.6 km/h. A driver from abroad who knows these landmarks can convert ft/s to km/h without a calculator while following a physics explanation.
Walking, running and cycling
A brisk walker moves at 4.4 ft/s, 4.8 km/h. A jogger moves at 9 ft/s, 9.9 km/h. A commuter on a bicycle manages 20 ft/s, 21.9 km/h. Fitness apps differ in the unit they show, but each pace corresponds to a single speed.
Wind and weather
A breeze of 20 ft/s is 21.9 km/h and a strong wind of 60 ft/s is 65.8 km/h, which falls in Beaufort force 8. American engineering reports on wind loads give numbers in ft/s, mph or knots, so a reader abroad needs to know which one is in front of them.
Cricket pace bowling
A cricket pitch is 66 feet long, so a ball at 132 ft/s needs half a second to cover it, ignoring the slowdown after the bounce. In km/h, that is 144.8. Fast bowlers above 150 km/h, which is 136.7 ft/s, are rare, and the best of them top 160 km/h, 145.8 ft/s, in short bursts.
The speed of sound
Sound travels at 1,125 ft/s, 1,234 km/h, at 20 degrees Celsius and at 1,116 ft/s, 1,225 km/h, at 15 degrees. A jet at 2,000 ft/s moves at 2,195 km/h, about Mach 1.8. Old aerodynamics texts quote ft/s as a matter of course.
Falling objects
A fall of 3 feet ends at 13.9 ft/s, which is 15.2 km/h. A fall of 10 feet, around 3 metres, ends at 25.4 ft/s, 27.8 km/h, and one of 30 feet ends at 43.9 ft/s, 48.2 km/h. Safety sheets use such equivalences to compare a fall with a collision.
Trains
An American passenger train at 79 mph moves at 115.9 ft/s, which is 127.1 km/h. In 20 seconds it covers 2,320 feet, 707 metres. Engineers use this kind of figure to decide how far a driver must see the level crossing ahead.
Stopping distance
A car at 88 ft/s, 96.6 km/h, on dry road with friction 0.7 stops in 172 feet, 52.4 metres. At 44 ft/s, 48.3 km/h, it stops in 43 feet, 13.1 metres. Halving the speed cuts the stopping distance to a quarter, so an error in the converted speed is magnified.
Traffic signals
An American formula sets the yellow signal as 1 second plus speed divided by twice a deceleration of 10 ft/s². At 66 ft/s, 72.4 km/h, that is 4.3 seconds. At 88 ft/s, 96.6 km/h, it is 5.4 seconds. Engineers elsewhere reach similar timings starting from km/h.
Pedestrian crossings
US guidance assumes a walking speed of 3.5 ft/s, 3.84 km/h, for timing crossing signals. A street 60 feet wide, 18.3 metres, therefore needs about 17 seconds. Slower speeds, such as 3 ft/s, 3.3 km/h, are used near care homes and hospitals.
What a second looks like
At 44 ft/s a vehicle covers 44 feet, 13.4 metres, in a second. At 88 ft/s it covers 26.8 metres, so a two-second gap is 53.6 metres at 96.6 km/h. The two-second rule works in either system.
Video games and simulations
Engines for games and simulators often keep their internal values in feet per second when they follow American sources. A car at 150 ft/s in the code corresponds to 164.6 km/h on the dashboard of the European version. Developers localising a title for several markets check this conversion.
Measurement tolerance
A radar with a tolerance of one mph is accurate to 1.47 ft/s, or 1.6 km/h. A report claiming that a driver exceeded a limit by just 1 km/h cannot be sustained if the device's tolerance is larger than the excess.
Two routes to the same number
You can go from ft/s to km/h in one step with 1.0973, or through m/s by multiplying by 0.3048 and then by 3.6. Both routes give 1.09728. If a calculation does not come out the same by both, a digit has been copied wrongly.
Tennis serves
The fastest serves measured exceed 160 mph, or 235 ft/s. The ball from the baseline to the service line is in the air for a third of a second. At 240 ft/s the 78-foot court is crossed in 0.325 seconds. In km/h, that is 263, which is how broadcasters present it in most countries.
Exchange visitors and students
Students on exchange from abroad meet problems in ft/s and formulas with g = 32.174 ft/s². A card with 44 ft/s = 48 km/h, 66 ft/s = 72 km/h and 88 ft/s = 97 km/h removes the need for repeated arithmetic in lectures and makes each “convert ft/s to km/h” calculation a simple lookup.
Hockey shots
The hardest shots in professional ice hockey are around 108.8 mph, which is 159.6 ft/s or 175 km/h. A 170 gram puck at that speed carries about 200 J of kinetic energy and covers the 18 metres from the blue line to the net in around 0.37 seconds.
Badminton smashes
The shuttlecock is the fastest object in racquet sport. A smash at 565 km/h is 514.9 ft/s, or 351 mph. Over a court half 6.7 metres long it takes only about a twentieth of a second to arrive. Because the shuttle slows quickly, the quoted speed is the peak just after contact.
Golf drives
A professional driver sends the ball away at about 249 ft/s, which is 170 mph and 273.6 km/h. The ball spends more than five seconds in the air for a long drive. Launch monitors in the US usually show mph, while European tour data use km/h or m/s.
Cycling and skiing
A downhill skier tops 150 km/h, 136.7 ft/s, and a ski jumper leaves the ramp at around 90 km/h, 82 ft/s. A sprint cyclist reaches 80 km/h, 72.9 ft/s. Coaches in different countries share data, and each has to agree on the unit before comparing performance.
The mental shortcut
To convert ft/s to km/h in your head, add 10 per cent to the figure in ft/s. For 88 ft/s: 88 plus 8.8 is 96.8, close to the exact 96.56. For 150 ft/s: 150 plus 15 is 165, against 164.6. The error is under 0.3 per cent.
Spreadsheet formulas
To convert ft/s to km/h in a spreadsheet, place the ft/s values in column A and enter =A2*1.09728 in column B. For the reverse, =B2/1.09728. A third column with =A2*0.681818 gives mph, so you can cross-check with the numbers on a radar gun.
More values for convert ft/s to km/h
A longer list of conversions
If the value you need is not in the first list, these further conversions may be close enough to read off directly:
- 0.1 ft/s = 0.109728 km/h
- 0.5 ft/s = 0.54864 km/h
- 3 ft/s = 3.29184 km/h
- 4 ft/s = 4.38912 km/h
- 7 ft/s = 7.68096 km/h
- 15 ft/s = 16.4592 km/h
- 20 ft/s = 21.9456 km/h
- 75 ft/s = 82.296 km/h
- 200 ft/s = 219.456 km/h
- 500 ft/s = 548.64 km/h
- 2,000 ft/s = 2,194.56 km/h
- 10,000 ft/s = 10,972.8 km/h
Common slips when you convert ft/s to km/h
Dividing by 1.0973
From ft/s to km/h the number grows. If 88 ft/s turned into 80, you used the factor for the opposite direction.
Confusing ft/s and mph
One ft/s is not one mile per hour. 88 ft/s is 60 mph, but 88 mph is 129 ft/s. The confusion produces an error of 47 per cent.
Rounding too early
If the speed will be squared in a braking or energy formula, keep the full digits until the final result.
Short answers
How do I convert ft/s to km/h?
Multiply the ft/s figure by 1.0973.
How many km/h is 88 ft/s?
96.56 km/h.
How many km/h is 100 ft/s?
109.73 km/h.
How many ft/s is 1 km/h?
0.9113 ft/s.
Does my number leave my device?
No, the calculation runs in your browser.
More pages and a wrap-up
For other speed conversions see Convert ft/s to m/s, Convert ft/s to mph, Convert m/s to km/h, Convert knots to km/h, Convert km/h to Mach, Convert km to mi, Convert mi to km, Convert °C to °F, Convert °F to °C. The reverse direction is Convert km/h to ft/s.
In short, a “convert ft/s to km/h” calculation comes down to multiplying by 1.0973 and writing the unit beside the answer. Your number is computed locally, with no account and no upload.