Great Circle Distance Calculator
Updated recently with improved calculation accuracy and expanded examples.
Compute the shortest distance between two locations on Earth using latitude and longitude. Results in nautical miles and kilometers.
Last updated: August 28, 2026
Author: OceanCalc Editorial Team · Publisher: Albor Digital LLC
Great Circle Distance Calculator
Result
Distance (nautical miles)
3007.7
Distance (km)
5570.2
Formula
Haversine: d = 2R × asin(√(sin²(Δlat÷2) + cos(lat1)×cos(lat2)×sin²(Δlon÷2)))This calculation uses a spherical-Earth model, so results are an approximation of real-world geographic distance.
What is the Great Circle Distance Calculator?
The great circle distance is the shortest path between two points on the surface of a sphere (Earth). It follows the arc of a circle whose center is the Earth's center.
A great circle is any circle on Earth's surface whose center is the planet's center. The shortest route between two points lies along the unique great circle that passes through both.
great circle
A great circle is the shortest path between two points on a sphere; long ocean routes are often planned as great-circle tracks with rhumb-line legs for practical steering.
rhumb line
A rhumb line crosses meridians at a constant bearing; it is simpler to steer than a great circle but is not the shortest path on the globe.
Related Maritime Calculators
Overview
A great circle is the shortest path between two points on a sphere; long ocean routes are often planned as great-circle tracks with rhumb-line legs for practical steering. A Great Circle Distance Calculator is used in maritime navigation to perform precise calculations based on established nautical formulas. This tool allows you to apply your inputs to the stated nautical relationships using accurate and standardized methods.
Key takeaways
- Rhumb line — A rhumb line crosses meridians at a constant bearing; it is simpler to steer than a great circle but is not the shortest path on the globe.
- Great Circle Distance Calculator — A great circle is the shortest path between two points on a sphere; long ocean routes are often planned as great-circle tracks with rhumb-line legs for practical steering.
- Formula — Haversine formula: a = sin²(Δlat/2) + cos(lat₁)×cos(lat₂)×sin²(Δlon/2); c = 2×atan2(√a, √(1−a)); d = R × c.
- How to use — Enter numbers in the fields above; results update as you change inputs.
How to use
Enter numbers in the fields above; results update as you change inputs.
Formula
Core relationship: Haversine: d = 2R × asin(√(sin²(Δlat/2) + cos(lat1)×cos(lat2)×sin²(Δlon/2)))
Haversine formula: a = sin²(Δlat/2) + cos(lat₁)×cos(lat₂)×sin²(Δlon/2); c = 2×atan2(√a, √(1−a)); d = R × c. R ≈ 3,440.065 nautical miles (Earth radius).
A great circle is any circle on Earth's surface whose center is the planet's center. The shortest route between two points lies along the unique great circle that passes through both. OceanCalc uses a spherical Earth model for this calculation, so results are an approximation of the corresponding ellipsoidal geodesic distance.
Practical use cases
Great Circle Distance Calculator: passage planning, crew briefings, instrument-to-chart unit checks, and verifying mental math when tired or in rough weather.
Tips for accuracy
- Match input units to your chart, GPS, or instrument before trusting the Great Circle Distance Calculator.
- Cross-check important outputs with a second method or crew when visibility or motion is poor.
- Treat simplified models (waves, radar horizon, etc.) as estimates; real conditions vary.
Practical examples
- New York to London: ~3,007.7 nm (~5,570.2 km)
- 1° of latitude ≈ 60 nm (along a meridian)
- Equator: 1° longitude = 60 nm; at 60°N, 1° longitude ≈ 30 nm
Frequently Asked Questions
What is great circle distance?
The great circle distance is the shortest path between two points on the surface of a sphere (Earth). It follows the arc of a circle whose center is the Earth's center. Sailing or flying great circle routes minimizes distance.
How is great circle distance calculated?
The haversine formula uses the latitudes and longitudes of both points to compute the central angle between them, then multiplies by Earth's radius (in nautical miles, about 3,440) to get distance.
Why use nautical miles for great circle?
One nautical mile is approximately one minute of latitude (the exact length varies slightly with latitude on the reference ellipsoid), so great circle distance in nm relates closely to angular distance. For example, 60 nm is approximately 1° of arc along a great circle.
How accurate is this calculator?
It uses standard maritime formulas and noted approximations. Use it for planning and checks; confirm safety-critical decisions with official sources.
Can I use this on mobile?
Yes. Layouts are responsive for phones and tablets on deck or in the cockpit.
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These calculations are based on standard maritime navigation formulas used in seamanship, chart navigation, and marine route planning.
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Results are estimates for educational purposes only and should not be used for real navigation decisions.