Distance & Bearing Calculator

A great-circle distance is the shortest path between two points on the surface of a sphere. Unlike driving distance, which follows roads, or straight-line distance on a flat map, the great-circle route curves around the Earth's surface. This is the route followed by ships crossing oceans, aircraft flying intercontinental legs, and any navigation system that must account for the Earth's curvature.

The term "great circle" refers to any circle formed by the intersection of the Earth's surface and a plane passing through the Earth's centre. The equator and every line of longitude are great circles. Parallels of latitude (except the equator) are not great circles, which is why flights from London to Los Angeles curve north over Canada rather than flying due west.

Haversine vs. Vincenty — Which Formula Should You Use?

The Haversine formula treats the Earth as a perfect sphere. It is extremely fast and accurate to within about 0.3% of the true geodetic distance — around 3 km over a 1,000 km route. For most applications — GIS analysis, logistics routing, app development, and quick field estimates — Haversine is the right choice.

The Vincenty formula uses the WGS84 ellipsoid model (semi-major axis 6,378,137 m, flattening 1/298.257223563). It converges iteratively to sub-millimetre accuracy, making it mandatory for survey work, aviation charts, precision marine navigation, and any calculation where millimetre-level accuracy matters. The only edge case is antipodal points (opposite sides of the Earth), where Vincenty can fail to converge; this calculator automatically falls back to Haversine in those rare cases.

How Forward and Back Bearing Work

Bearing is measured in degrees clockwise from true north (0° = North, 90° = East, 180° = South, 270° = West). The forward bearing is the compass direction you face at Point A when pointing toward Point B. The back bearing is the direction you face at Point B when pointing back toward Point A.

Because the Earth is a sphere, the back bearing is not simply the forward bearing plus 180°. On long intercontinental routes, the difference can be significant. For example, flying from London to New York, the forward bearing is roughly 288° (WNW). The back bearing from New York to London is approximately 51° (NE) — not 108°. This is because great-circle routes curve relative to lines of latitude, changing compass direction continuously along the route.

Distance and Bearing in Aviation, Marine, and Surveying

In aviation, bearing is called a true track or magnetic bearing (after applying magnetic declination). Flight plans specify the initial true track from departure to destination. Long-haul aircraft continuously recalculate bearing because the great-circle track constantly changes heading — what pilots call the rhumb line correction.

Marine navigators use great-circle sailing for ocean passages. A vessel sailing from Cape Town to Buenos Aires follows a great circle that dips well south of the direct rhumb line, saving hundreds of kilometres. The initial bearing is plotted as a series of straight rhumb-line segments that approximate the curve.

In land surveying, Vincenty bearings are used when measuring property boundaries or control networks. Even at distances of 5–10 km, the difference between spherical and ellipsoidal bearing can exceed the survey closure tolerance.

Common Route Distances and Bearings

How to Use CSV Batch Mode

Switch to the CSV Batch tab to calculate distances for multiple coordinate pairs at once. The format is straightforward:

The first row must be a header (any text — it is skipped). Each subsequent row is one coordinate pair. Maximum 500 rows per submission. All batch calculations use the Haversine formula.