Convert Knots to Feet per Second
Knots to feet per second is the conversion that comes up when a nautical or aviation speed needs to be compared against the imperial units used in US engineering and physics. One knot is about 1.687810 feet per second, so the number gets bigger when you switch from knots to ft/s.
Knots to Feet per second conversion table
| Knots (kn) | Feet per second (ft/s) |
|---|---|
| 1 | 1.68781 |
| 2 | 3.37562 |
| 3 | 5.06343 |
| 5 | 8.439049 |
| 10 | 16.878099 |
| 20 | 33.756197 |
| 50 | 84.390493 |
| 100 | 168.780986 |
| 500 | 843.904929 |
| 1,000 | 1,687.809857 |
The formula
To convert knots to feet per second, multiply the speed in knots by 1.687810:
ft/s = knots × 1.687810
A worked example
Say a gust front is measured at 60 knots and an engineer needs that in feet per second for a wind-load calculation:
60 × 1.687810 = 101.27 ft/s
That's a violent, damaging gust — well into the range that can down tree limbs and power lines.
Why it's an approximation
A nautical mile equals exactly 1852 meters and a foot equals exactly 0.3048 meters, but knots measure distance per hour while feet per second measures it per second. Converting between the two means dividing by 3600, and that division doesn't land on a short, clean decimal — so 1.687810 is the standard rounded factor, accurate for any practical use but not a perfectly exact ratio.
When you'll use it
Wind-load and structural engineering calculations, ballistics and projectile-speed work, and any US-based physics or engineering context that needs a nautical or aviation speed translated into feet per second.
Frequently asked questions
How many feet per second are in a knot?
About 1.687810 ft/s. A knot covers a bit under two feet every second, so the number grows by roughly 70% when you convert.
Is the knots to ft/s conversion exact?
No — it's an approximation. The nautical mile is exactly defined in meters, and a foot is exactly defined in meters too, but combining those with the hours-to-seconds conversion produces a long decimal that gets rounded to 1.687810.
Where do I typically see speeds in feet per second instead of knots?
Feet per second shows up in US engineering, ballistics, and physics contexts — things like wind-load calculations or projectile speeds — while knots stay in aviation and marine navigation. Converting between them bridges those two worlds.