Nautical Distance Converter

Convert between nautical miles, fathoms, cables, kilometres, and statute miles — for marine navigation, charts, and depth.

Nautical Distance

nautical miles, fathoms, cables

From

Result

1.852

1 nmi = 1.852 km

Popular conversions

What Is a Nautical Distance Converter?

A nautical distance converter translates marine measurements between units — nautical miles to kilometres, fathoms to metres, cables to nautical miles. Sea and air navigation use their own distance units, chief among them the nautical mile, which equals one minute of latitude (1,852 m). This ties distance directly to position on a chart, which is why mariners and aviators have used it for centuries.

This converter routes through the metre. It handles the nautical mile, the fathom (6 feet, for depth), the cable (one-tenth of a nautical mile), and bridges back to statute miles and kilometres. Because the nautical mile is about 15% longer than the land mile, mixing the two is a real navigation hazard the converter helps avoid.

This is one category of the full Unit Converter — pair it with our percentage calculator or scientific calculator for related everyday maths.

How Nautical Distance Conversion Works

Everything routes through the metre

Each unit has a fixed metre value. The converter normalises to metres, then projects to nautical miles, fathoms, cables, and land units.

A nautical mile = one minute of latitude

1 nmi = 1,852 m, defined so that one minute of arc along a meridian equals one nautical mile. This links distance to chart position.

Fathoms measure depth

One fathom is 6 feet (1.829 m). Sea charts traditionally mark depth in fathoms, from the old practice of measuring by armspan.

Cables subdivide the mile

One cable is one-tenth of a nautical mile (185.2 m). Used for short distances like the length of an anchor rode or harbour spacing.

Core Nautical Distance Factors

Multiply to reach metres; divide to come back.

Nautical mile → km

× 1.852

One nautical mile is exactly 1.852 km, or about 1.151 statute miles.

Fathom → m

× 1.8288

One fathom is 6 feet = 1.8288 m, the traditional depth unit.

Cable → m

× 185.2

One cable is one-tenth of a nautical mile = 185.2 m.

How to Use the Nautical Distance Converter

1
Enter the distance
Type the marine distance or depth you want to convert — a passage length, a chart distance, a sounding.
2
Choose the 'from' unit
Pick nautical miles, fathoms, cables, kilometres, or statute miles as your starting unit.
3
Choose the 'to' unit
Select the target unit, or swap the two to reverse direction.
4
Read every unit at once
The all-units table shows the distance across nautical miles, fathoms, cables, and km together.

Key Nautical Distance Concepts

Nautical mile

1,852 m, equal to one minute of latitude. The standard distance unit at sea and in the air, tying distance directly to chart position.

Fathom

Six feet (1.829 m), the traditional unit of water depth. 'By the mark, twain' meant two fathoms — the origin of Mark Twain's pen name.

Cable

One-tenth of a nautical mile (185.2 m). Used for short marine distances such as anchor rode length or vessel separation.

Knot connection

A knot is one nautical mile per hour, so nautical distance and boat speed share the same mile — making time-distance navigation clean.

Real-World Nautical Conversions

⛵

Passage planning

A 60-nautical-mile passage is 111.1 km or 69 statute miles. Charts and pilots use nautical miles throughout.

🌊

Charted depth

A 10-fathom sounding is 18.3 m or 60 feet. Older charts mark depth in fathoms; newer ones in metres.

⚓

Anchoring

Letting out 3 cables of chain is 555.6 m. Cables express short distances like anchor scope and harbour spacing.

✈️

Aviation distance

Aircraft navigation also uses nautical miles — a 400-nmi leg is 741 km. Airspeed in knots pairs naturally with it.

🗺️

Latitude rule

One degree of latitude is 60 nautical miles, since each minute is one nmi. Mariners read distance straight off the chart's latitude scale.

🚢

Ship's log

A vessel logging 240 nmi in a day averaged 10 knots. Distance and speed share the nautical mile, simplifying the math.

Best Practices for Nautical Distance Conversion

✓Never confuse nautical and statute miles. A nautical mile (1,852 m) is ~15% longer than a land mile. Mixing them in navigation introduces a systematic, compounding error.
✓Use the latitude scale for distance. On a chart, one minute of latitude equals one nautical mile. Measure distance against the latitude scale, never the longitude scale.
✓Pair nautical miles with knots. Since a knot is one nautical mile per hour, keeping distance in nautical miles makes speed-time-distance navigation arithmetic clean.
✓Know your chart's depth unit. Charts mark depth in fathoms or metres depending on edition. Confirm which before interpreting soundings to avoid grounding.
✓Use cables for short ranges. For harbour and anchoring distances, cables (0.1 nmi) are more natural than fractions of a nautical mile.

Common Nautical Distance Mistakes

Treating nautical as statute miles

The nautical mile is ~15% longer. Using a land mile in navigation underestimates distance and can put a vessel off course.

Reading the longitude scale for distance

Only the latitude scale gives nautical miles directly. Longitude minutes shrink toward the poles, so they misstate distance.

Confusing fathom units on charts

Some charts use fathoms, others metres. Misreading a depth unit risks running aground in shallow water.

Mixing cables and nautical miles

A cable is 0.1 nmi. Treating cables as nautical miles overstates short distances tenfold.

Why Nautical Distance Conversion Matters

Marine and air navigation run on the nautical mile precisely because it equals one minute of latitude, letting navigators read distance straight off a chart and pair it cleanly with speed in knots. But the nautical mile is about 15% longer than the land mile, so confusing the two — or misreading a chart's fathom-versus-metre depths — is a genuine safety hazard at sea.

Converting accurately between nautical miles, fathoms, cables, and the metric and statute units keeps passage planning, depth interpretation, and position-keeping reliable. A converter that routes through the metre and keeps the nautical and land miles distinct lets sailors, navigators, and aviators work confidently across charts of every edition and origin.

Built for sailors, navigators, aviators, and marine professionals converting between nautical miles, fathoms, cables, and kilometres.

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Nautical Distance Converter FAQs

A nautical mile is exactly 1,852 metres, equal to 1.852 km or about 1.151 statute (land) miles. It's defined as one minute of arc of latitude, which means distance on a chart can be read directly from the latitude scale — the reason it has been the navigation standard for centuries.

A nautical mile (1,852 m) is about 15% longer than a statute, or land, mile (1,609.344 m). The nautical mile is tied to the Earth's geometry — one minute of latitude — while the statute mile is a historical land measure. Confusing them in navigation causes a systematic distance error.

A fathom is a unit of water depth equal to 6 feet, or 1.8288 metres. It comes from the span of a sailor's outstretched arms, once used to measure depth by hand-lowered line. Traditional sea charts mark depths in fathoms, though many modern charts now use metres.

A cable is one-tenth of a nautical mile, equal to 185.2 metres (about 608 feet). It's used for short distances at sea, such as the length of anchor chain paid out, the separation between vessels, or distances within a harbour, where a full nautical mile would be too large.

Because a nautical mile is defined as one minute of latitude, and there are 60 minutes in a degree. So one degree of latitude equals 60 nautical miles (about 111 km). This neat relationship lets navigators measure distances directly against the latitude markings on a chart.

It uses exact definitions (1 nautical mile = 1,852 m, 1 fathom = 6 ft = 1.8288 m, 1 cable = 185.2 m, 1 statute mile = 1,609.344 m) and routes every conversion through the metre at full precision, so the result is exact to your input precision.