Distance & bearing calculator
Enter two positions in either decimal degrees (36.45) or degrees / minutes (36 27.0 N / 014 30.0 E). The calculator returns:
- Great-circle distance & initial course — the shortest path on the sphere; bearing changes along the route.
- Rhumb-line distance & constant course — the loxodrome, a single steered course; longer in middle and high latitudes.
- Passage time — at the speed you supply.
Spherical Earth assumed (mean radius 3440 NM / 6371 km). Vincenty's ellipsoidal formula gives slightly more accurate results on long passages but the spherical figure is normally within 0.5%. For voyage planning, always cross-check against the ship's ECDIS / passage plan.
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When to use this tool
Worked example
Scenario: Voyage Yokohama (35°26.6'N, 139°38.7'E) → Long Beach (33°45.6'N, 118°11.6'W). Vessel service speed 14.5 kn.
Great-circle: ~4,470 NM · initial course ~068° · passage time ~13 days.
Rhumb-line: ~5,220 NM · constant course ~091° · passage time ~15 days.
Interpretation: Great-circle saves ~750 NM (~2 days), but bulges to ~50°N and may add weather + parametric-roll risk in winter — weather-router will likely recommend a composite route splitting the difference.