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Distance Calculator

How far apart are two places, really? Pick any two cities or airports and this free distance calculator returns the straight line distance in kilometres and miles using the great circle formula, plus a realistic driving distance estimate for road trip planning. Use it to sanity check flight times, estimate fuel costs, compare routes, or settle the classic argument before you book, fast, accurate, and no sign up required.

Last updated: October 22, 2026

Written by Ateeq Fareedi · Last updated October 22, 2026

The city or airport you are starting from.

The city or airport you are going to.

Distance unit

The formula

  • haversine: d = 2R × arcsin(√(sin²(Δφ/2) + cos φ1 × cos φ2 × sin²(Δλ/2))), R = 6,371 km
  • miles = km × 0.621371
  • estimated_road_km ≈ straight_line_km × 1.3
  • coordinates come from the shared ~80 airport dataset

A worked example

Karachi (KHI) → London (LHR): straight line distance ≈ 6,340 km (3,940 miles); estimated road distance ≈ 6,340 × 1.3 ≈ 8,240 km.

More about the Distance Calculator

Straight line or road: which number to use

Pick the starting city and destination, choose km or miles, and the tool returns two numbers: the great circle distance, the shortest path over the Earth's surface, what planes roughly fly, and a road estimate at about 1.3× the straight line. Use the straight line figure to sanity check flight times and compare routes; use the road figure for driving day math and fuel estimates. The road number is a planning shortcut, not turn by turn directions, confirm exact routes in a maps app.

Chain the numbers: feed the road distance into the Fuel Cost Calculator with your car's real dashboard economy, not the brochure number, and you get the trip's fuel cost in one more step. Comparing two destinations? Run both pairs and divide by travellers; the per person distance settles which option the group should vote for.

A worked Sydney to Melbourne comparison

Enter Sydney and Melbourne and the straight line result comes back at about 713 kilometres, or 443 miles, the great circle path over the curve of the Earth. Suppose the road route you would actually drive measures 880 kilometres. The road is therefore about 1.23 times the crow flies figure, because 880 divided by 713 is roughly 1.23. That ratio is the sanity check to carry to other trips: a road result barely longer than the straight line, or several times longer, deserves a second look at the route.

Those two numbers feed different decisions. The 713 kilometres explains the flight: aircraft follow something close to the great circle line, so air time tracks the smaller figure. The 880 kilometres drives the fuel estimate, at 8 litres per 100 kilometres, the trip needs 880 times 8 divided by 100, which is 70.4 litres. Pricing a drive with the flight distance, or judging a flight by the road distance, quietly corrupts both calculations.

Turning one distance into a weekly commuting figure

A one way distance looks harmless until it is multiplied by a routine. Suppose a new job sits 25 kilometres from home. The daily round trip is 50 kilometres, a five day week makes 250 kilometres, and over a 48 week working year that is 12,000 kilometres, a figure that belongs in any honest comparison of salary, fuel and wear on the car. Run the calculator for each candidate home or office and multiply before you decide, not after.

The same multiplication sharpens smaller choices: a school, gym or supermarket that is 3 kilometres farther away but visited twice a week adds about 624 kilometres a year, because 3 extra kilometres each way is 6 per round trip, twice weekly for 52 weeks. None of these sums needs the road estimate to be perfect, a consistent figure from the same tool, applied to every candidate, is what makes the comparison fair.

How to use the Distance Calculator

  1. Select the starting city or airport.
  2. Select the destination city or airport.
  3. Choose your preferred units (km or miles).
  4. Read the straight line distance and the estimated road distance.

Frequently asked questions

What's the difference between straight line and road distance?

Straight line (great circle) distance is the shortest path over the Earth's surface, what planes roughly fly. Road distance follows actual roads, which wind around terrain, so it's always longer. The road figure here is an estimate, not turn by turn directions.

Why is the road estimate only approximate?

The road figure is the straight line distance times a circuity factor (~1.3), a standard planner's shortcut, not turn by turn directions. Real routes vary with terrain and road networks, so use a maps app when you need exact driving directions.

Which cities can I compare?

Around 80 major cities and airports worldwide from the shared dataset, the same list the flight and time zone tools use.

Can I get the distance in miles?

Results show both kilometres and miles, so you do not even have to choose, but you can set a preferred unit.

How do I find the distance between two addresses?

For street addresses you will want a maps app. This tool works with around 85 major cities and airports, picked from two dropdowns. Choose the nearest city or airport to each address and you get the straight line distance plus a driving estimate in seconds.

Can the calculator tell me how long the drive will take?

The calculator gives you the distance, which is half the puzzle, divide it by your expected average speed and you will get a solid time estimate. On motorways at around 100 km/h (roughly 60 mph), the hours roughly equal the distance divided by a hundred. Just remember to add time for fuel stops, food breaks and traffic before you commit to an arrival time.

How is the flight distance between two cities calculated?

It uses the great circle (Haversine) formula from each city's coordinates, the shortest path over the Earth's surface. New York to London is about 5,570 km (3,461 miles). Real flown routes can be longer because of winds and airspace.

How do I calculate the distance between two cities?

Enter both city names into a distance calculator, which uses the great circle formula to give you the straight line distance in kilometers. Note that road distance is usually longer due to curves and real routes.

How accurate is the straight line distance between two cities?

Very accurate for what it measures: the formula works on the coordinates of the two place centres over a spherical Earth model, so the result is typically within a fraction of a percent of the true shortest surface distance. The uncertainty is in the endpoints, not the maths, a city centre pin can sit several kilometres from the airport or suburb you actually mean, and that choice moves the answer more than the formula ever will.