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Knots & Road Speed Unit Comparison

Show one speed in knots, mph, km/h, feet per second and meters per second.

  • Formula & worked example
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Calculator inputs

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How to use this calculator

  1. Enter the known values in the units shown. Results update as you type.
  2. Where results are editable, change one to solve backwards. Lock a value to hold it fixed.
  3. Use the worked example to check the method. Reset restores the starting fields.

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Inputs and results stay in this browser tab. Bookify does not upload or store the values you enter.

Formula and method

A speed of 90 knots is exactly 166.68 km/h and 46.3 m/s. The nautical mile is 1,852 meters; a statute mile used for mph is 1,609.344 meters.

Meters per second = knots × 1852 ÷ 3600; km/h = knots × 1.852

Worked example

Enter these known values and leave the other values blank.

Speed in knots
90 kn
Speed in miles per hour
103.57 mph
Speed in kilometers per hour
166.68 km/h
Speed in feet per second
151.9 ft/s
Speed in meters per second
46.3 m/s

Assumptions and limitations

  • Uses the international nautical mile, international foot and statute mile. These are unit conversions of the same speed; changing units does not adjust for wind, currents or other motion.
  • The arithmetic also accepts signed velocity components. A negative value keeps its sign across conversions; scalar speed is normally nonnegative.

Common questions

Does one knot mean one kilometer per hour?

No. One knot is one nautical mile per hour, equal to 1.852 km/h.

Can I start from mph or meters per second?

Yes. Enter the known speed in any field and the other fields update. Leave conflicting measurements blank or clear them.

References

The calculation equations, inverse formulas, units, and input rules were imported from this source. Bookify provides the interface and equation solver.

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