21 knots in kilometers per hour

Conversion

21 knots is equivalent to 38.892 kilometers per hour.^[1]

Conversion in the opposite direction

The inverse of the conversion factor is that 1 kilometer per hour is equal to 0.0257122287359868 times 21 knots.

It can also be expressed as: 21 knots is equal to $\frac{1}{0.0257122287359868}$ kilometers per hour.

Approximation

An approximate numerical result would be: twenty-one knots is about thirty-eight point eight nine kilometers per hour, or alternatively, a kilometer per hour is about zero point zero three times twenty-one knots.

Units involved

This is how the units in this conversion are defined:

Knots

"The knot (/nɒt/) is a unit of speed equal to one nautical mile (1.852 km) per hour, approximately 1.151 mph. The ISO Standard symbol for the knot is kn. The same symbol is preferred by the IEEE; kt is also common. The knot is a non-SI unit that is accepted for use with the SI. Worldwide, the knot is used in meteorology, and in maritime and air navigation—for example, a vessel travelling at 1 knot along a meridian travels approximately one minute of geographic latitude in one hour. Etymologically, the term derives from counting the number of knots in the line that unspooled from the reel of a chip log in a specific time."

Wikipedia page of knots

Kilometers Per Hour

"The kilometer per hour is a unit of speed, expressing the number of kilometres travelled in one hour. The unit symbol is km/h. Worldwide, it is the most commonly used unit of speed on road signs and car speedometers."

Wikipedia page of kilometers per hour

Footnotes

[1] The precision is 15 significant digits (fourteen digits to the right of the decimal point).

Results may contain small errors due to the use of floating point arithmetic.