Convert Miles to Nautical Miles

About converting Miles to Nautical Miles

Miles (mi) and Nautical Miles (nmi) are both units of length, so converting between them is a single multiplication: multiply your Miles figure by 0.869. Ten Miles comes to 8.6898 Nautical Miles, and a hundred works out at 86.8976 Nautical Miles.

Rule of thumb: going from Miles to Nautical Miles divides, so the figure always shrinks — it takes about 1.1508 Miles to make a single Nautical Mile. If your answer came out bigger, you have the conversion the wrong way round.

What is a Mile?

The mile descends from the Roman mille passus — a thousand paces, each pace being two steps. Its modern length of exactly 1,609.344 meters looks arbitrary because it is: the figure was fixed by the 1959 international yard and pound agreement, which defined the yard as exactly 0.9144 meters and let the mile fall out of it at 1,760 yards. It remains the road-distance unit of the United States and the United Kingdom, and the unit runners think in for road races.

What is a Nautical Mile?

A nautical mile is exactly 1,852 meters, and unlike every other unit here it was chosen to mean something geographically: it is one minute of latitude, one sixtieth of a degree. That is enormously convenient at sea and in the air, because a navigator can read distance straight off a chart’s latitude scale with dividers and no arithmetic. It is also the parent of the knot — one nautical mile per hour — which is why ships and aircraft report speed in knots rather than km/h.

To put both in perspective: a mile takes most people fifteen to twenty minutes to walk, while a nautical mile is one minute of latitude on any chart.

The converter above updates as you type, and the table lists common values for quick reference. Need the opposite direction? Use the Nautical Miles to Miles converter, or browse all Length converters.