What is knot?
A knot is a unit of speed equal to one nautical mile per hour, approximately 1.852 km/h. It is the international standard for maritime navigation, aviation, and meteorological wind speed reporting.
Real-world uses
Knots are the universal speed unit in maritime navigation and aviation worldwide, regardless of whether a country uses metric or imperial. Ship speeds, ocean currents, wind speed in aviation weather (METAR) reports, and jet stream velocities are all given in knots.
History
The knot originates from the 17th-century practice of measuring ship speed by throwing a log overboard attached to a rope with knots tied at regular intervals. Sailors counted how many knots paid out in a fixed time (measured by a sandglass).
Common mistakes
Saying "knots per hour"—a knot already means nautical miles per hour, so adding "per hour" is redundant and incorrect. Also, confusing knots with km/h: 1 knot ≈ 1.852 km/h.
What is foot per second?
Foot per second is a unit of speed in imperial and US customary systems. It is used in ballistics, sports science, and engineering calculations that rely on US customary units.
Real-world uses
Feet per second is used in ballistics for bullet muzzle velocities (e.g., 2,800 fps for a rifle round), aerospace engineering for aircraft approach speeds, and fluid dynamics in American engineering contexts. Elevator speeds are sometimes specified in ft/s.
History
Feet per second has been used in English-language engineering since the 18th century, particularly in artillery and ballistics. It remains the standard velocity unit in American firearms and aerospace industries despite the broader shift toward metric units.
Common mistakes
Confusing feet per second with miles per hour. 1 ft/s ≈ 0.682 mph, so they are quite different. Also, using fps as an abbreviation for both "feet per second" and "frames per second" creates ambiguity in technical documents.
When is this conversion used?
Converting knot to foot per second is useful in the speed domain when comparing values across different measurement standards or applying formulas that require a specific unit.
Worked examples
1 knot = 1.68780986 foot per second
1 foot per second = 0.3048 metre per second
How to convert knot to foot per second
To convert knot to foot per second, multiply the value by 1.68780986.
To convert foot per second back to knot, multiply by 0.5924838.
Measurement standards
The SI unit of speed is metres per second (m/s), a derived unit requiring no independent definition. The knot is defined as exactly one nautical mile (1,852 metres) per hour and is sanctioned for maritime and aeronautical navigation by the International Civil Aviation Organization.
Did you know?
The fastest human-made object is the Parker Solar Probe, which reached 635,266 km/h (about 176 km/s) in 2024 during a close pass of the Sun — fast enough to travel from New York to Tokyo in under a minute.
Quick reference: knot to foot per second
| knot | foot per second |
|---|---|
| 0.1 | 0.16878099 |
| 0.5 | 0.84390493 |
| 1 | 1.68780986 |
| 2 | 3.37561971 |
| 5 | 8.43904928 |
| 10 | 16.87809857 |
| 25 | 42.19524642 |
| 50 | 84.39049285 |
| 100 | 168.7809857 |
| 250 | 421.95246424 |
| 500 | 843.90492848 |
| 1,000 | 1,687.80985696 |
Common values
| knot | foot per second | |
|---|---|---|
| Walking speed | 2.72138229 knot | 4.59317585 foot per second |
| City speed limit | 27.01943845 knot | 45.60367454 foot per second |
| Highway driving | 60.84233262 knot | 102.69028871 foot per second |
| Commercial aircraft | 485.96112315 knot | 820.20997375 foot per second |
| Speed of sound (sea level) | 661.47084239 knot | 1,116.43700787 foot per second |
Available Speed units
More knot conversions
- Convert knot to metre per second
- Convert knot to kilometre per hour
- Convert knot to mile per hour
- Convert knot to foot per second
- Convert knot to metre per minute
- Convert knot to kilometre per second
- Convert knot to mach (approx at sea level)
- Convert knot to centimetre per second
- Convert knot to mile per minute
Assumption: Mach uses an approximate sea-level reference (about 340.29 m/s).