Calcylator
Nautical Miles to Kilometres

Nautical miles to km:
multiply by 1.852

Convert nautical miles to kilometres for sailing, flying and shipping, with a chart, worked examples and the nautical versus statute mile trap.

Calcylator Editorial Team

Updated · 5 min read

How many kilometres are in a nautical mile?

One nautical mile is exactly 1.852 kilometres, which is 1,852 metres. The figure is a fixed international definition, so it carries no rounding error.

A nautical mile is about 15 percent longer than the statute mile used on roads, which is 1.609344 km. The two are easy to confuse because both are called a mile, but they are never interchangeable on a chart or a flight plan.

The nautical miles to km formula

Nautical miles to kilometres =km = nmi × 1.852
km:
distance in kilometres
nmi:
distance in nautical miles
1.852:
kilometres in one nautical mile (exact)
To go the other way, multiply km by 0.5399568035, or divide by 1.852.

  • Distance

    12 nmi

  • Multiply

    12 × 1.852

Distance in km

22.224 km

Twelve nautical miles is the usual limit of territorial seas under the UN Convention on the Law of the Sea.

In reverse, 100 km is 100 × 0.5399568035 = 54.0 nautical miles. A rough check is to double the nmi figure and take off about 7 percent.

  1. Write the distance in nautical miles as a decimal.
  2. Multiply by 1.852 to get kilometres.
  3. For km to nautical miles, divide by 1.852.
  4. Check: the km figure should be a little under double the nmi figure.

Chart: nautical miles to km from 1 to 1000

These values are exact, because the factor is a clean decimal.

Nautical miles to kilometres
Nautical milesKilometres
11.852
23.704
59.26
1018.52
2546.3
5092.6
100185.2
250463
500926
10001852

Reading across: 10 nautical miles is 18.52 km and 100 nautical miles is 185.2 km.

Where nautical miles are used

Sailors, pilots and ship captains measure distances in nautical miles because one is close to one minute of latitude, which makes chart work simple. Speed is quoted in knots, and one knot is one nautical mile per hour.

Take a coastal passage of 45 nmi. In kilometres that is 45 × 1.852 = 83.34 km, which a driver or a rescue coordinator working in metric units can compare with a road distance.

A flight leg of 450 nmi is 833.4 km. Going backwards, a ferry route of 25 km is about 13.5 nautical miles, a figure a skipper would plot on a chart.

Common mistakes with nautical miles and km

  • Treating a nautical mile as a statute mile. Using 1.609 instead of 1.852 gives an answer about 13 percent too small.
  • Dividing when you should multiply. A nautical mile is longer than a kilometre, so the km figure is bigger.
  • Mixing up knots with miles per hour. One knot is one nautical mile per hour, about 1.852 km/h, not 1 km/h.
  • Rounding to 1.85 on long routes. On 1,000 nmi that drops 2 km.

Common questions

How many km is 1 nautical mile?

One nautical mile is exactly 1.852 km, or 1,852 metres. This is a fixed definition, so it is not a rounded figure. It is a little longer than the statute mile, which is about 1.609 km.

How do I convert nautical miles to km?

Multiply the nautical miles by 1.852. For example, 25 nmi is 25 × 1.852 = 46.3 km. For a rough check, double the nautical miles and take off a little, which gives about 46 km.

How many nautical miles are in 100 km?

There are about 54.0 nautical miles in 100 km, found by multiplying 100 by 0.5399568035. The same result comes from dividing 100 by 1.852. That is why a 100 km sea crossing feels shorter on a chart than on a road map.

Is a nautical mile longer than a mile?

Yes. A nautical mile is 1.852 km, while a statute mile is 1.609344 km, so the nautical mile is about 15 percent longer. Never swap one for the other when planning a sea or air route.

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