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.

See also

• · Unit converters — knots / km·h, NM / km, °C / °F.
• · COLREGs — Rule 8 (action to avoid collision), Rule 19 (restricted visibility).
• · Port database — UN/LOCODE-keyed records you can paste coordinates from.