Radar Horizon Calculator

Written by Great Medico

Updated September 25, 2026 •2 min read

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Small input changes can matter a lot in radar horizon, especially when angles, squared dimensions, ratios, or logarithms are involved. Light calculations often combine tiny wavelengths with macroscopic distances, making unit discipline especially important. That is why the useful part of this calculator is the relationship as well as the headline value.

What this calculator does

This calculator isolates the relationship between Atmospheric refraction?, Radar system height, Target height and radar horizon with refraction. That makes it easier to see which input is controlling the result and to distinguish the headline quantity from secondary values shown underneath.

How to use it

For a clean calculation, enter Radar system height, Target height exactly as defined by the labels and their units. Choose Atmospheric refraction? so the calculation path matches your case. Check the headline value, then scan the supporting metrics for a relationship that should obviously increase or decrease with one input; this is a fast way to catch an entry mistake.

How the calculation works

The geometric horizon for height h is d = √(2Rh+h²). With atmospheric refraction enabled, the page replaces Earth radius R with 4R/3. It calculates the radar horizon and the target’s horizon separately, then adds them for the maximum line-of-sight distance.

Example

Using the default example on the page (Atmospheric refraction? = Yes; Radar system height = 20 m; Target height = 5 m), the calculator returns radar horizon with refraction of 18.433314 km. That default case is a convenient baseline: alter only one field and compare the new result before substituting a completely different setup.

How to interpret the result

Read the radar-horizon number as the line-of-sight distance from the radar height alone and the maximum distance as the sum of radar and target horizons. Turning refraction on increases the effective Earth radius and therefore extends the geometric horizon in this model.

Limitations and notes

Real optical systems can add aberration, alignment error, finite bandwidth, diffraction, scattering, detector response, and component tolerances beyond the ideal relationship shown here. For this page, verify Radar system height, Target height first; a wrong unit or convention there can outweigh any benefit from extra decimal precision. Critical design or acceptance work should still be checked against the applicable standard and measured data.