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21 Knots to Feet per Second

21 knots equals 35.44 feet per second. Use the formula, worked example, and conversion table below to check the math.

21 kn = 35.44 ft/s
kn × 1.687808 = ft/s
Try: 16 kn to ft/s 20 kn to ft/s 22 kn to ft/s 26 kn to ft/s
21 kn is also
21 kn = 24.17 mph 21 kn = 38.89 km/h 21 kn = 10.8 m/s
kn
35.44 ft/s

How to Convert Knots to Feet per Second

kn × 1.687808 = ft/s
  1. Start with 21 kn
  2. Multiply by 1.687808: 21 × 1.687808 = 35.44
  3. Result: 21 kn = 35.44 ft/s

The same formula works for any value. Multiply by 1.687808 to go from knots to feet per second.

Common Knot to Foot per Second Conversions

Knots (kn) Feet per Second (ft/s)
1 kn 1.69 ft/s
2 kn 3.38 ft/s
5 kn 8.44 ft/s
10 kn 16.88 ft/s
15 kn 25.32 ft/s
20 kn 33.76 ft/s
21 kn 35.44 ft/s
25 kn 42.2 ft/s
50 kn 84.39 ft/s
75 kn 126.59 ft/s
100 kn 168.78 ft/s
250 kn 421.95 ft/s
500 kn 843.9 ft/s
1,000 kn 1,687.81 ft/s
calculate Knot to Foot per Second Converter swap_horiz Foot per Second to Knot Converter functions Knot to Foot per Second Formula speed All Speed Conversions

Frequently Asked Questions

21 knots equals 35.44 feet per second.
The formula is: kn × 1.687808 = ft/s. See the kn to ft/s formula page for worked examples.
Use the feet per second to knots converter. The reverse formula is: ft/s × 0.592484 = kn.
The calculator uses the full-precision conversion factor for accuracy. Table values and displayed results are rounded for readability.
The conversion formula (kn × 1.687808 = ft/s) is based on internationally defined standards. Displayed results are rounded for readability, while the calculator uses the full-precision factor.
person Written by Sean Day verified Reviewed by UnitCompare update Last updated Mar 28, 2026