What is the Haversine formula and why does this tool use it?

Haversine finds the great-circle distance between two points on a sphere from their latitude and longitude. It is numerically stable for the small angles real point pairs produce, where a naive law-of-cosines loses precision. Example: Beijing (39.9042, 116.4074) to Shanghai (31.2304, 121.4737) returns about 1067 km, which matches published city-to-city figures within a percent.

How does great-circle distance differ from a straight line?

A great-circle distance is the shortest path along the curved surface of the Earth, the route a plane actually flies. A straight line would tunnel through the planet and is always shorter. For New York to Los Angeles the great-circle surface distance is about 3936 km, while the straight chord through the Earth is a few kilometres less. This tool reports the surface distance, which is what you want for travel and mapping.

How is the initial bearing calculated and what do N, NE, SSW mean?

The initial bearing, or forward azimuth, is the compass heading you would set off on from point A to reach point B along the great circle. It is measured clockwise from due north, so 0 is north, 90 is east, 180 is south, 270 is west. The tool also snaps the degree value to a 16-point compass label: 45 degrees becomes NE, 202.5 becomes SSW. The bearing changes as you travel, which is why it is called the initial bearing.

Which distance unit should I read, km, mi, m or nmi?

All four come from the same metre result, so pick by context. Kilometres and miles suit road and travel distances, metres suit short hops where decimals of a kilometre are awkward, and nautical miles (1 nmi = 1852 m) are standard for aviation and marine navigation. For example 1000 m shows as 1 km, 0.621 mi and 0.540 nmi at once, so you never have to convert by hand.

What Earth radius does this assume and how accurate is it?

It uses a spherical Earth with a mean radius of 6371 km, the standard Haversine assumption. The real Earth is a slightly flattened ellipsoid, so Haversine carries a worst-case error of roughly 0.3 to 0.5 percent versus a full ellipsoidal model like Vincenty. For a 1000 km leg that is a few kilometres, fine for travel planning, geocaching and general mapping. If you need survey-grade precision, use an ellipsoidal calculator instead.

Does it handle points across the equator or the 180-degree line?

Yes. Distances across the equator are ordinary, so 1 degree south to 1 degree north spans about 222 km. The antimeridian near 180 longitude is the tricky case: from 179 east to 179 west is only 2 degrees of longitude, about 222 km at the equator, not most of the way around the planet. The formula takes the short way automatically, and the midpoint normalises its longitude to the -180 to 180 range.

Estimate a flight or road leg between two cities

You have the coordinates of two cities and want the as-the-crow-flies distance before booking. Paste both lat/long pairs and read the great-circle distance in kilometres and miles at once. New York to Los Angeles returns about 3936 km, close to the published flight distance, so you can sanity-check a fare-per-km or a fuel estimate without a map.

Set a heading for sailing or hiking navigation

Planning a passage by boat or a long off-trail walk, you need the initial bearing as well as the distance. Enter your start and your waypoint and the tool gives the forward azimuth in degrees plus a compass label like NE, so you can set a heading on a handheld compass and know roughly how far the leg runs in nautical miles.

Find the meeting midpoint for two locations

Two people in different towns want to meet halfway. Drop both sets of coordinates in and the great-circle midpoint comes back as its own lat/long, which you can paste into a map to find a cafe or station near the geographic middle, rather than guessing from a road map.

Sanity-check a distance function while coding

Building a feature that computes distance between GPS points, you want a trusted reference value to test against. Feed your fixture coordinates here, copy the metre and kilometre output, and assert your own Haversine implementation lands within a percent. The exported pure functions mirror the textbook formula, so they make a clean oracle.

Teach or learn the Haversine formula with real numbers

Working through spherical trigonometry in a class, you want concrete input and output to check the formula by hand. Use the sample points, compare the distance, bearing and midpoint the tool reports, and trace each step. The share link reopens the exact example for a worksheet or a study group.

Coordinate Distance Calculator (Haversine, Great-Circle)

Great-circle distance between two lat/long points with the Haversine formula, plus bearing and midpoint, all in your browser

Runs locally
Category Calculator
Best for Getting a realistic range before a purchase, plan, workout, or schedule decision.

Point A

Latitude-90 to 90

Longitude-180 to 180

Point B

Latitude-90 to 90

Longitude-180 to 180

Sample points

Distance

1,067.31

663.196

1,067,310

576.301

nmi

Initial bearing

153.07° SSE

Midpoint

35.593729, 119.07801

What this tool does

A coordinate distance calculator that finds the great-circle distance between two latitude/longitude points using the Haversine formula on a spherical Earth with a mean radius of 6371 km. Type two decimal-degree points and read the distance at once in kilometres, miles, metres and nautical miles. It also gives the initial bearing from point A to point B as a degree value and a 16-point compass label such as NE or SSW, and the great-circle midpoint as its own lat/long pair. The math handles the cases a flat distance breaks on: pairs that cross the equator, pairs that cross the antimeridian near 180 longitude, and identical points that should return zero. Latitude is checked against the -90 to 90 range and longitude against -180 to 180, so a typo is caught before it skews the answer. One click copies the full result, and the URL carries all four coordinates so a shared link reopens the exact same pair. Everything runs locally in the page, with no server call and no coordinate ever uploaded.

Tool details

Input: Numbers; The page exposes text boxes, numeric controls, file pickers, or structured inputs depending on the tool.
Output: Live result + Copy; The result area focuses on usable output, with copy, download, or preview actions when supported.
Privacy: Browser-side processing; The main tool logic does not call an external API, so inputs normally stay in the current tab.
Save / share: Shareable URL state; Key settings are encoded in the URL so another person can reopen the same setup.
Performance budget: Initial JS <= 9 KB; No WASM budget is declared, keeping the tool quick to open on mobile.
Best fit: Calculator · Developer; Category and role tags drive related tools, internal links, and quick fit checks.

How to use

1. Input

Paste or drop your content into the tool panel.
2. Process

Click the button. All processing is local in your browser.
3. Copy / Download

Copy the result or download to disk in one click.

How Coordinate Distance Calculator fits into your work

Use it for fast estimates, comparisons, and planning numbers before you make the final call.

Calculation jobs

Getting a realistic range before a purchase, plan, workout, or schedule decision.
Comparing scenarios by changing one input at a time.
Turning rough assumptions into a number you can discuss.

Calculation checks

Double-check units, dates, rates, and rounding assumptions.
Treat health, finance, tax, and legal outputs as planning aids, not professional advice.
Save the inputs that produced an important result so you can reproduce it later.

Good next steps

These links move the current task into a more complete workflow.

Real-world use cases

Estimate a flight or road leg between two cities
You have the coordinates of two cities and want the as-the-crow-flies distance before booking. Paste both lat/long pairs and read the great-circle distance in kilometres and miles at once. New York to Los Angeles returns about 3936 km, close to the published flight distance, so you can sanity-check a fare-per-km or a fuel estimate without a map.
Set a heading for sailing or hiking navigation
Planning a passage by boat or a long off-trail walk, you need the initial bearing as well as the distance. Enter your start and your waypoint and the tool gives the forward azimuth in degrees plus a compass label like NE, so you can set a heading on a handheld compass and know roughly how far the leg runs in nautical miles.
Find the meeting midpoint for two locations
Two people in different towns want to meet halfway. Drop both sets of coordinates in and the great-circle midpoint comes back as its own lat/long, which you can paste into a map to find a cafe or station near the geographic middle, rather than guessing from a road map.
Sanity-check a distance function while coding
Building a feature that computes distance between GPS points, you want a trusted reference value to test against. Feed your fixture coordinates here, copy the metre and kilometre output, and assert your own Haversine implementation lands within a percent. The exported pure functions mirror the textbook formula, so they make a clean oracle.
Teach or learn the Haversine formula with real numbers
Working through spherical trigonometry in a class, you want concrete input and output to check the formula by hand. Use the sample points, compare the distance, bearing and midpoint the tool reports, and trace each step. The share link reopens the exact example for a worksheet or a study group.

Common pitfalls

Swapping latitude and longitude. Latitude runs -90 to 90 and comes first; longitude runs -180 to 180. Entering 116 as a latitude is impossible and the tool flags it, but a value like 40 in both slots silently points somewhere wrong, so always confirm lat before long.
Mixing degrees-minutes-seconds with decimal degrees. This tool wants decimal degrees, so 40 degrees 42 minutes north is 40.7, not 40.42. Typing the minutes after the point inflates the position by a wide margin and throws the distance off by hundreds of kilometres.
Forgetting the sign for western longitude and southern latitude. West is negative and south is negative. Dropping the minus on a Los Angeles longitude (writing 118.24 instead of -118.24) places the point in the wrong hemisphere and balloons the distance.

Privacy

Every step runs as plain JavaScript inside your browser tab: the Haversine distance, the bearing, the midpoint and the unit conversions. No coordinate, result or share link is ever sent to a server, and nothing is logged. The one thing to know: the share URL encodes all four coordinates in the query string, so pasting a share link into a chat will record those coordinates in the recipient server's access log. For a sensitive location, use the copy button and paste the text instead of sharing the URL.

FAQ

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Coordinate Distance Calculator (Haversine, Great-Circle)

What this tool does

Tool details

How to use

1. Input

2. Process

3. Copy / Download

How Coordinate Distance Calculator fits into your work

Calculation jobs

Calculation checks

Good next steps

Real-world use cases

Estimate a flight or road leg between two cities

Set a heading for sailing or hiking navigation

Find the meeting midpoint for two locations

Sanity-check a distance function while coding

Teach or learn the Haversine formula with real numbers

Common pitfalls

Privacy

FAQ

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