One nautical mile per hour, which is exactly 1.852 km/h or about 1.15 mph. Ships and aircraft use it because it maps directly onto latitude on a chart.

Is mach a fixed speed?

No — it's the speed of sound, which falls as air gets colder. This converter uses 340.29 m/s, the value at sea level at 15°C. At cruising altitude the speed of sound is noticeably lower.

Speed Converter

Convert speeds between the units used on roads, at sea, in the air and in physics. Every conversion shows the same speed in all the other units underneath — useful when a car is quoted in mph, a wind forecast in knots and a running pace in metres per second.

Value

From

100 kilometres per hour =

62.1371 miles per hour

metres per second: 27.7778
kilometres per hour: 100
knots: 53.9957
feet per second: 91.1344
mach (at sea level): 0.08162972

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Why use this tool

Road, marine, aviation and scientific units in one place
Knots defined exactly as one nautical mile per hour
Full conversion table under every answer
Instant and free

How it works

1Enter the speed you want to convert.
2Choose the units to convert from and to.
3Read the answer and the full table.

Speed Converter — frequently asked questions

100 km/h is 62.14 mph. A useful mental shortcut is that mph is roughly km/h divided by 1.6, so 80 km/h is about 50 mph and 120 km/h is about 75 mph.

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