Line of Sight Calculator

To use line of sight (LOS) calculator, Enter Height 1 (meters): Input height of first point above ground level.

Enter Height 2 (meters): Input height of second point above ground level

Select Refraction Factor: Choose atmospheric condition (Standard 0.13, High 0.25, None 0)

The calculator computes the total visible range, horizon distances, and Fresnel zone details

This LOS calculator uses precise formulas to compute maximum visible distance between two points, considering Earth’s curvature and atmospheric refraction.

Line of Sight Distance Table

Line of Sight Formula

The equation for calculating line of sight distance is:

d = √(2Rh₁) + √(2Rh₂)

Where:

• d represents total distance in meters
• h₁, h₂ represent heights in meters
• R represents effective Earth radius

Effective Earth Radius:

R = 6371000/(1-k)

Where:

• k is the refraction factor (typically 0.13)
• 6371000 is Earth’s radius in meters

Example calculation for 30m height:

R = 6371000/(1-0.13) = 7323000
d = √(2×7323000×30) = 22.2 km

Fresnel Zone Calculation:

r = 8.657 × √(d/f)

Where:

• r is radius in meters
• d is distance in kilometers
• f is frequency in GHz

The basic Line of Sight formula involves trigonometry and considers several key variables:

h = h₁ + (h₂ - h₁)(d₁/D)

Where:

• h = Height at any point along the line of sight
• h₁ = Height of the first point
• h₂ = Height of the second point
• d₁ = Distance from first point to the point being calculated
• D = Total distance between the two points

How do you measure the line of sight?

• Determine the endpoints: Record the height and location of both points, Calculate the straight-line distance between them
• Account for Earth’s curvature: Apply the curvature correction formula, Consider atmospheric refraction (typically 14% reduction in curvature)
• Plot the path profile: Calculate heights at regular intervals, Compare with terrain elevation data
• Evaluate clearance: Ensure the line of sight clears all obstacles with sufficient margin

• Radio Tower Link
  • Tower A: Height 200ft, Elevation 1000ft
  • Tower B: Height 150ft, Elevation 1200ft
  • Distance: 10 miles
  • Midpoint height = 1000 + 200 + (350/10 × 5) = 1375ft
• Solar Panel Installation
  • Rooftop: Height 30ft, Elevation 500ft
  • Tree line: Height 60ft, Elevation 490ft
  • Distance: 100ft
  • Clearance needed = 500 + 30 – (490 + 60) = -20ft (obstruction exists)
• Security Camera Placement
  • Camera: Height 20ft, Elevation 100ft
  • Target area: Height 0ft, Elevation 95ft
  • Distance: 200ft
  • LOS height at 100ft = 100 + 20 + (-25/200 × 100) = 107.5ft
• Military Observation Post
  • Post: Height 10ft, Elevation 2000ft
  • Target: Height 0ft, Elevation 1800ft
  • Distance: 3000ft
  • Midpoint clearance = 1900ft (accounting for terrain)
• Satellite Dish Alignment
  • Dish: Height 5ft, Elevation 200ft
  • Building: Height 40ft, Elevation 210ft
  • Distance: 150ft
  • Required elevation adjustment = 45ft up

What is Line of Sight?

Line of sight represents the unobstructed path between two points. In RF planning and optical systems, this path must consider Earth’s curvature and atmospheric effects. The visible range increases with height and is enhanced by atmospheric refraction.

The effective range depends on installation height, atmospheric conditions, and required clearance for the specific application. Professional installations typically require additional margin for reliability.