What is a nautical mile?

An international nautical mile (NM) is exactly 1,852 meters (1.852 km), according to the NIST conversion factor. Its navigation use is historically tied to angular measurement on the Earth.

What is the Haversine formula?

The Haversine formula calculates the great-circle distance between two points on a sphere given their latitudes and longitudes. It accounts for Earth's curvature and is accurate to within 0.3% for most practical distances.

What is the difference between great-circle and rhumb-line distance?

A great circle (orthodrome) is the shortest path over the Earth, but its course changes continuously. A rhumb line (loxodrome) holds one compass course and is longer except along a meridian or the equator. London to New York is 3,007.7 NM by great circle (initial course 288.3°) but 3,128.6 NM on a constant 258.0° rhumb line, 120.9 NM more. On short coastal legs the two are almost identical, which is why passages are often sailed as a series of rhumb-line legs between great-circle waypoints. This tool shows both.

How accurate is the result?

Great-circle and rhumb-line figures use a sphere with the 6,371 km mean radius, which can differ from the true ellipsoidal distance by up to about 0.5%. The WGS-84 line uses Vincenty's inverse formula on the GPS ellipsoid and is accurate to well under a metre. For marine use the bigger issue is that none of them route around land, hazards or regulations; use charts and navigation systems for passage planning.

How do I enter degrees and minutes from a chart?

Type them as you read them: 27°48.315′N, 27 48.315 N or 27-48.315N all work, and so does N 27 48.315. Add seconds as a third number (27 48 18.9 N). N and E are positive, S and W negative, so 82°37.5′W equals -82.625. The result panel echoes each point back in decimal degrees so you can check the conversion.

Is this an actual sea-route distance?

No. It is the shortest spherical surface arc between the two coordinates and may cross land or unsafe water. Actual voyage distance depends on waypoints, coastlines, traffic schemes, weather and operating restrictions.

What coordinate format should I use?

Decimal degrees (-33.8688), degrees and decimal minutes (33°52.13′S) or degrees, minutes and seconds (33 52 7.7 S). Positive values or N/E are North/East; negative values or S/W are South/West. Latitude ranges from -90 to 90, longitude from -180 to 180.

What do the courses represent?

The initial great-circle course is the true heading (0–360°) at departure on the shortest route, and the final course is the heading on arrival; the two differ because a great circle crosses each meridian at a different angle. The rhumb-line course is the single true course that, held the whole way, reaches the destination on a longer track. Apply variation and deviation to convert true to compass courses.

How many nautical miles is it from New York to Cuba?

From New York City to Havana the straight great-circle distance is about 1,138 NM using city-center coordinates. That line crosses land, so a boat sailing around Florida covers more. Add waypoints as separate legs to estimate the real passage.

Is there a map to click points on?

No. The calculator takes typed coordinates, which you can copy from any map app (in Google Maps, right-click a spot and click the coordinates) or a chart plotter. For a route with turns, list the turning points in the waypoints box: the tool returns every leg and the route total.

How long does it take to sail 100 nautical miles?

Time = distance ÷ speed in knots. At 6 knots, typical for a cruising sailboat, 100 NM takes 16 h 40 min; at 20 knots it takes 5 h. Enter a speed above to get the underway time for the direct line and for every waypoint leg, then add time for currents, weather and stops.

Nautical Distance Calculator

Enter two coordinates in decimal degrees or chart-style degrees and minutes for great-circle, rhumb-line (constant course) and WGS-84 distances, courses, optional waypoint legs and underway time at a chosen speed. This is not a navigable sea route and does not avoid land or hazards.

Nautical miles between two points = the great-circle angle between them × Earth's radius ÷ 1,852 m.

Origin

Latitude

Longitude

Decimal degrees (positive = N/E, negative = S/W) or degrees-minutes(-seconds) with N/S/E/W, e.g. 27 48.315 N.

Destination

Latitude

Longitude

Quick presets:

Optional waypoints between origin and destination

Separate latitude and longitude with a comma or semicolon. Adds a leg-by-leg table and route total.

Optional constant speed (knots)

Produces ideal underway time only; excludes stops, currents, weather and route detours.

Enter coordinates or choose a preset, then click Calculate.

Nautical Miles

— NM

Kilometers

— km

Statute Miles

— mi

Initial Course (GC)

—

Final Course (GC)

—

Reverse Bearing

—

Origin: —

Destination: —

Rhumb Line (constant course)

— NM

Course — · —

WGS-84 Ellipsoid

— NM

Vincenty geodesic, GPS datum

Route Legs

Leg	GC NM	Rhumb NM	Course	Time

Straight great-circle geometry only. The line can cross land and unsafe or restricted water; do not use it as a navigable passage plan.

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Common Passages: Great Circle vs Rhumb Line

Straight coordinate-to-coordinate geometry between harbour areas (spherical Earth, 6,371 km). Real routes around headlands, reefs and traffic schemes are longer.

Passage	Great circle	Initial course	Rhumb line	Rhumb course
Miami → Nassau	160.0 NM	105.0°	160.0 NM	105.6°
Fort Lauderdale → Bimini	51.3 NM	117.4°	51.3 NM	117.6°
Newport, RI → St. George's, Bermuda	632.3 NM	147.7°	632.4 NM	149.9°
San Diego → Cabo San Lucas	703.8 NM	145.1°	703.9 NM	146.9°
Los Angeles → Honolulu	2,219.9 NM	260.8°	2,229.8 NM	250.4°
Seattle → Juneau	774.4 NM	330.5°	775.3 NM	325.9°
Las Palmas → Rodney Bay, St Lucia	2,667.7 NM	261.3°	2,677.5 NM	251.6°
Southampton → New York	2,973.4 NM	288.0°	3,087.3 NM	258.6°

Quick answer

Nautical miles between two points = the great-circle angle between them × Earth's radius ÷ 1,852 m. One minute of latitude is about one nautical mile, so 27°48.315′N to 27°51.328′N on the same meridian is a 3.013′ change, or about 3.0 NM.

Examples

Route (city-center coordinates)	Nautical miles	Initial bearing
Miami – Havana	198.5	217.2°
New York – Havana	1,137.9	204.3°
Newport Beach – Honolulu	2,235.9	261.2°
London – New York	3,007.7	288.3°

Enter two coordinates (decimal or degrees-minutes) and an optional speed in knots to get great-circle and rhumb-line nautical miles, courses and underway time.

Summary

This tool calculates spherical great-circle distance between two coordinates using the Haversine formula, the constant-course rhumb-line distance, and the WGS-84 ellipsoidal distance (Vincenty). Coordinates can be decimal degrees or chart-style degrees, minutes and seconds. Results include nautical miles, kilometres, statute miles, initial and final great-circle courses, the rhumb-line course, multi-leg waypoint totals and optional travel time at a constant speed. It is a geometric coordinate-to-coordinate distance—not a charted sea route around land, shoals, traffic schemes or restricted waters.

How it works

Enter the latitude and longitude of your starting point (Origin).
Enter the latitude and longitude of your destination point.
Type each coordinate as signed decimal degrees (40.7128), degrees and decimal minutes (40°42.77′N or 40 42.77 N) or degrees, minutes and seconds.
The tool applies the Haversine formula for the great-circle distance and the Mercator-based rhumb-line formula for a constant-course track.
It also solves Vincenty's inverse formula on the WGS-84 ellipsoid, the datum used by GPS and most charts.
Results appear in nautical miles, kilometers and statute miles with initial and final great-circle courses and the rhumb-line course.
Optionally list waypoints to get a leg-by-leg table and route total, and a speed in knots for underway time.

Use cases

Screen coordinate-to-coordinate distance and ideal underway time.
Calculate flight distances for aviation route planning.
Compare geometric legs before chart-based route planning.
Verify chart plotter readings with an independent calculation.
Estimate fuel requirements for marine or aerial journeys.
Cross-reference GPS coordinates in navigation training exercises.
Compare distances for search-and-rescue planning.
Compute leg distances for a multi-waypoint passage plan.

Frequently Asked Questions

Last updated: 2026-10-09 · Reviewed by Nham Vu

Nautical Distance Calculator

Use the Nautical Distance Calculator

Origin

Destination

Common Passages: Great Circle vs Rhumb Line

Quick answer

Examples

Summary

How it works

Use cases

Frequently Asked Questions