Calculate the great-circle distance between two points on Earth using their latitude and longitude coordinates.
Nautical Miles (NM)
Kilometers (km)
Miles (mi)
Distance: —
Understanding Nautical Distance Calculation
Calculating the shortest distance between two points on the surface of a sphere, like Earth, is known as finding the great-circle distance. This is crucial for maritime navigation and aviation to plot efficient and direct routes. The Haversine formula is commonly used for this purpose, as it's more numerically stable for small distances than some other methods.
The Haversine Formula
The Haversine formula calculates the distance between two points on a sphere given their longitudes and latitudes. The formula requires coordinates in radians, so degree inputs must first be converted.
Let:
lat1, lon1 be the latitude and longitude of the first point (in radians)
lat2, lon2 be the latitude and longitude of the second point (in radians)
R be the radius of the sphere (Earth).
The formula involves these steps:
Calculate the difference in latitudes: Δlat = lat2 - lat1
Calculate the difference in longitudes: Δlon = lon2 - lon1
The calculator uses a standard radius of 3440.06 nautical miles for nautical mile calculations and converts as needed for other units.
Use Cases for Nautical Distance Calculation
Maritime Navigation: Essential for determining distances between ports, planning voyage legs, and calculating fuel consumption for ships.
Aviation: Used by pilots and air traffic control to plan flight paths, estimate flight times, and manage airspace, especially for over-water flights.
Mapping and GIS: For geographical information systems to measure distances between locations on maps.
Geospatial Analysis: Determining proximity between geographical features or points of interest.
Logistics and Shipping: Planning optimal routes for sea freight.
This calculator simplifies the process, allowing users to quickly find the great-circle distance without manual computation. Ensure accurate latitude and longitude inputs for precise results.
function degreesToRadians(degrees) {
return degrees * Math.PI / 180;
}
function calculateNauticalDistance() {
var lat1 = parseFloat(document.getElementById("lat1").value);
var lon1 = parseFloat(document.getElementById("lon1").value);
var lat2 = parseFloat(document.getElementById("lat2").value);
var lon2 = parseFloat(document.getElementById("lon2").value);
var unit = document.getElementById("unit").value;
var resultDiv = document.getElementById("result");
var resultSpan = resultDiv.getElementsByTagName("span")[0];
// Input validation
if (isNaN(lat1) || isNaN(lon1) || isNaN(lat2) || isNaN(lon2)) {
resultSpan.innerHTML = "Please enter valid numbers for all coordinates.";
resultDiv.style.backgroundColor = "#dc3545"; // Red for error
return;
}
if (lat1 90 || lat2 90) {
resultSpan.innerHTML = "Latitude must be between -90 and 90 degrees.";
resultDiv.style.backgroundColor = "#dc3545";
return;
}
if (lon1 180 || lon2 180) {
resultSpan.innerHTML = "Longitude must be between -180 and 180 degrees.";
resultDiv.style.backgroundColor = "#dc3545";
return;
}
var R_nm = 3440.06; // Earth's radius in Nautical Miles
var lat1Rad = degreesToRadians(lat1);
var lon1Rad = degreesToRadians(lon1);
var lat2Rad = degreesToRadians(lat2);
var lon2Rad = degreesToRadians(lon2);
var dLat = lat2Rad – lat1Rad;
var dLon = lon2Rad – lon1Rad;
var a = Math.sin(dLat / 2) * Math.sin(dLat / 2) +
Math.cos(lat1Rad) * Math.cos(lat2Rad) *
Math.sin(dLon / 2) * Math.sin(dLon / 2);
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 – a));
var distance = R_nm * c;
var finalDistance = distance;
var unitLabel = "NM";
if (unit === "km") {
finalDistance = distance * 1.852; // 1 NM = 1.852 km
unitLabel = "km";
} else if (unit === "mi") {
finalDistance = distance * 1.15078; // 1 NM = 1.15078 miles
unitLabel = "mi";
}
resultSpan.innerHTML = finalDistance.toFixed(2) + " " + unitLabel;
resultDiv.style.backgroundColor = "var(–success-green)"; // Green for success
}
function resetCalculator() {
document.getElementById("lat1").value = "";
document.getElementById("lon1").value = "";
document.getElementById("lat2").value = "";
document.getElementById("lon2").value = "";
document.getElementById("unit").value = "nm";
document.getElementById("result").getElementsByTagName("span")[0].innerHTML = "–";
document.getElementById("result").style.backgroundColor = "var(–success-green)"; // Reset to default success green
}