Trip Distance Calculator

The Trip Distance Calculator estimates trip distance. Simply enter your coordinates to calculate your distance and great-circle distance. This tool finds the shortest path between two points on the Earth's surface to help with travel planning.

Enter start latitude (-90 to 90) and longitude (-180 to 180) in decimal degrees
Enter end latitude (-90 to 90) and longitude (-180 to 180) in decimal degrees
Select the unit for the result (km or mi)

This calculator is for informational purposes only. It estimates the straight-line distance and does not account for actual road routes, traffic, or terrain. Verify results with appropriate mapping tools for travel planning.

What Is Trip Distance

Trip distance is the length of the path between two places on Earth. This tool calculates the shortest straight line over the surface of the Earth, known as the great-circle distance. It helps you understand how far apart two cities or points are from each other in a direct line.

How Trip Distance Is Calculated

Formula

d = 2 × R × arcsin( √[ sin²((φ2 − φ1)/2) + cos(φ1) × cos(φ2) × sin²((λ2 − λ1)/2) ] )

Where:

  • d = Distance between two points
  • R = Radius of Earth (6371 km or 3959 mi)
  • φ1, φ2 = Latitudes of start and end points in radians
  • λ1, λ2 = Longitudes of start and end points in radians

This formula measures the angle between the two points on a sphere. It uses math to turn the Earth's round shape into a flat circle for the calculation. By measuring the curve of the Earth between the points, it finds the truest path without using simple flat maps.

Why Trip Distance Matters

Knowing the straight-line distance helps you plan trips and estimate travel time. It gives you a baseline for how long a journey might be if there were no roads or obstacles in the way.

Why Great-Circle Distance Is Important for Travel Planning

Relying only on straight-line distance can be risky for driving. Real roads have curves, mountains, and detours that make the trip longer. Using this number alone may cause you to underestimate your travel time or fuel needs significantly.

Trip Distance vs. Road Distance

This calculator shows the straight line through the air. Real driving distance is usually longer because you must follow roads. For example, a direct path might cross a river or mountain that requires a long detour to drive across. Always check a map tool for actual driving times and routes.

Related Calculators

Calculation logic verified using publicly available standards.

View our Accuracy & Reliability Framework →