How this calculator works
A knot is one nautical mile per hour. The international nautical mile is exactly 1,852 metres, so one knot is exactly 1.852 kilometres per hour. Ships and aircraft use knots because a nautical mile is close to one minute of latitude, which makes navigation on a chart easier. Converting to land speed is a single multiplication by 1.852.
Formula
km/h = knots x 1.852. mph = km/h / 1.609344. m/s = km/h / 3.6. ft/s = m/s / 0.3048.
Worked example
100 knots is 185.2 km/h, 115.078 mph, 51.444 m/s and 168.781 ft/s. 20 knots is 37.04 km/h. A 50 km/h speed limit is 26.998 knots.
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Frequently asked questions
Why is a knot 1.852 km/h?
The international nautical mile was fixed at exactly 1,852 metres in 1929. One nautical mile per hour is therefore exactly 1.852 km/h, with no rounding in the definition.
Is a knot the same as a mile per hour?
No. A knot is about 15 per cent faster than a statute mile per hour. 100 knots is about 115 mph.
Why do ships use knots rather than km/h?
A nautical mile is approximately one minute of latitude, so a speed in knots maps directly to minutes of latitude per hour on a chart. That made dead reckoning simpler before electronic navigation.