GPS Distance Calculator — Straight-Line Distance Between Two Points

It is accurate to within about 0.3–0.5%. The formula models the Earth as a perfect sphere of mean radius 6,371 km, whereas the real Earth is an oblate spheroid (6,378 km at the equator, 6,357 km at the poles). For cycling distances under a few hundred kilometres the spherical error is negligible — far smaller than the difference between this straight-line figure and the actual ridden route.

Yes. This is the great-circle (as-the-crow-flies) distance between two points. It is the shortest possible path over the surface of the Earth, so your actual ridden distance will always be LONGER — roads wind, switchback up climbs and rarely run dead straight. On typical UK roads the ridden route is commonly 20–40% further than the straight-line distance.

No, and deliberately so. A point-to-point straight-line distance has no single climb to apply slope geometry to, and total elevation gain over a winding route cannot be combined with one crow-flies horizontal leg in a single Pythagoras triangle. The extra ground covered by climbing is also tiny: a 150 m gain over a 60 km route adds under 20 cm. The dominant reason your route is longer is road winding, not elevation — use a route planner (Komoot, Ride with GPS, Strava) for true ridden distance.

Use Google Maps (right-click any point and click the decimal coordinates to copy), your bike GPS computer, or your smartphone. Coordinates are in decimal degrees: positive north/east, negative south/west — e.g. 51.5074, -0.1278 for London (51.5° N, 0.13° W).

It is the initial compass bearing (forward azimuth) you would set off on to head straight towards the end point, measured clockwise from true north: 0°/360° = north, 90° = east, 180° = south, 270° = west. On a great circle the bearing changes along the way, so this is the bearing at the start point only.