Earth Curve Calculator
Calculate the distance to the horizon and the hidden height due to Earth's curvature. Perfect for surveyors, sailors, and outdoor enthusiasts.
Published by:
isCalculator Editorial Team
Was this calculator helpful?
How to use this tool?
How to Use the Earth Curve Calculator
- Enter Observer Height (required): Type your eye level above sea level in meters (e.g., 1.7 m). This is the only mandatory input.
- Enter Target Height (optional): If you want to calculate how much of a distant object is hidden, enter its height in meters (e.g., 0 for sea level).
- Enter Distance (optional): Input the distance to the target in kilometers (e.g., 10 km). This is needed to compute hidden height.
- Click "Calculate" or press Enter in any input field to update results.
Results explained:
- Distance to Horizon – How far you can see until the Earth’s curvature hides the ground (in km).
- Hidden Height – The portion of a target (in meters) that is blocked by curvature. Shows 0.00 if the target is fully visible.
- Drop per km – The average drop of the Earth’s surface over 1 km (≈ 0.0785 m).
Note: All inputs must be in metric units (meters for heights, kilometers for distance). The calculator uses Earth’s radius as 6371 km.
Previous Results
| Result | Inputs | Date |
|---|
Frequently Asked Questions
It calculates the distance to the horizon based on your height above sea level, and the hidden height of an object at a given distance due to Earth's curvature.
Using the formula: distance (km) = 3.57 * sqrt(height in meters). This approximates the distance to the horizon assuming standard atmospheric refraction.
Hidden height is the portion of a distant object that is obscured by the curvature of the Earth. It depends on the observer's height, the object's height, and the distance.