Distance Calculator

Distance calculator: how far apart are two places?

This distance calculator measures the straight-line distance between two places — the shortest path over the Earth’s surface, often called the great-circle or “as the crow flies” distance. Pick cities from the built-in list, type latitude and longitude, or press Use my location, and you get the answer in kilometres, miles and nautical miles, together with the compass bearing, the midpoint, a rough flight time and a small map of the route.

The list holds 195 Indian cities, including every state and union territory capital, plus world capitals and about 130 other major cities. Use it to plan a flight, see how far a relative’s town is, size a delivery zone or log a sailing passage in nautical miles. The maths runs in your browser, and your location is read only when you press the button.

How to use the Distance Calculator

1. Type a city in box A and pick it from the list (arrow keys and Enter work too), or type coordinates such as 28.6139, 77.2090 or 28°36′50″N 77°12′32″E.
2. Do the same in box B. Each place’s coordinates appear under its box, so you can check the right one was chosen.
3. Press Add stop for a trip with several legs; each leg and the running total appear under the map.
4. Choose km, miles or nautical miles for the main result, then press Copy summary to paste the numbers elsewhere.

Distance Calculator features

How the distance is calculated

The Earth is not a perfect sphere: it is about 43 km wider across the equator than from pole to pole. The calculator therefore uses Vincenty’s inverse formula (1975) on the WGS-84 ellipsoid (equatorial radius 6,378,137 m, flattening 1/298.257223563). It iterates until the answer stops changing and reports the geodesic — the shortest path on the ellipsoid — and the starting bearing.

For two points almost exactly opposite each other on the globe, Vincenty’s method can fail to converge. In that rare case the calculator switches to the haversine formula on a sphere with the mean Earth radius of 6,371.0088 km and marks the answer with “≈”; the error is then up to about 0.5%.

Worked example: New Delhi (28.6000° N, 77.2000° E) to Mumbai (19.0189° N, 72.8550° E) is 1,149.5 km, which is 714.3 miles or 620.7 nautical miles. You would set off on a bearing of 203.6° (SSW), the midpoint is 23.8262° N, 74.9476° E, and the rough flight time is 1 h 56 min. A simple spherical calculation gives 1,153.1 km for the same points — 3.6 km more — which is why the ellipsoid matters.

Straight-line distance is not road distance

Roads bend around hills, rivers, coastlines and borders, so the distance you drive is always longer than the straight line. This page does not estimate driving distance — the road distance calculator routes along real roads.

As a rough rule of thumb only, road routes tend to be about 1.2 to 1.4 times the straight line. Ballou, Rahardja and Sakai (2002) reported average “circuity factors” of 1.20 for the United States, 1.31 for India and 1.40 for England, and Boscoe, Henry and Zdeb (2012) found US driving routes to hospitals were 1.42 times the straight-line distance. Mountains, lakes and sea crossings push the figure much higher.

For a road trip, take the distance from your map app, estimate the journey time with the speed calculator and the fuel bill with the fuel cost calculator.

Kilometres, miles and nautical miles

Pilots and sailors use the nautical mile because it is very close to one minute of arc of latitude, which makes chart work simple. The length converter handles other units.

Bearings, midpoints and flight times

• Initial bearing is the compass direction at the start, clockwise from true north. On a great circle the heading changes as you go: London to New York starts at 288.4° (WNW) but arrives heading roughly south-west.
• Midpoint is halfway along the shortest path; with several stops it is the halfway point of the whole route.
• Rough flight time is this page’s own rule of thumb: an average 800 km/h plus 30 minutes per leg for take-off, climb, descent and landing. Winds, routing and delays change real times; check arrival times with the time zone converter.