About Earth Curve Calculator
Providing accessible, scientifically accurate, and visually intuitive models of Earth's geometry and refraction dynamics.
Our Mission
Earth Curvature Calculator tool was founded to bridge the gap between complex geodetic calculations and daily observation. Whether you are a surveyor checking sights across a bay, a photographer trying to capture a distant lighthouse, or a physics student learning about Earth's dimensions, our goal is to provide a tool that is mathematically exact yet simple to use.
Many online calculators rely on loose approximations, such as the basic 8 inches per mile squared rule, without explaining their limits. HorizonCalc uses standard trigonometric and Pythagorean models with adjustable refractive factors to ensure that what you see on the screen matches what is seen in the field.
Rigorous Geodesy
Calculations are based on the average WGS84 volumetric radius of 6,371 km. We avoid flat approximations in favor of true spherical geometry to ensure model integrity.
Refraction Analysis
Light bending can alter visual targets by up to 15%. Our standard 7/6 R refraction toggle models real-world conditions for optimal predictions.
Dynamic SVG Diagram
Interactive geometry showing observer line of sight, horizon tangent points, and target visible segments updates dynamically as you type.
Dynamic Curves
Integrated Chart.js plotting plots obscured heights across a spectrum of distances to see the visual boundary slope instantly.
Our Principles
Open Access
No paywalls or accounts. The calculator is completely free to use for anyone, anywhere.
Scientific Integrity
No adjustments for biases. Formulas represent standard geodetic science and light refraction mathematics.
Privacy First
Calculations run directly in your browser. None of your height or location queries are sent to any server.