Line-of-Sight Distance Calculator
Radio signals on VHF, UHF, and higher frequencies generally travel by line of sight. This calculator estimates the maximum theoretical communication distance between two antennas based on their heights above ground level. Calculations assume average atmospheric conditions, standard Earth curvature, and an unobstructed path.
Actual communication range may vary due to terrain, vegetation, buildings, atmospheric conditions, antenna gain, transmitter power, and receiver sensitivity.
Leave blank to calculate the radio horizon for a single antenna only.
These formulas use the standard radio horizon constant which accounts for typical atmospheric refraction of radio waves. The effective Earth radius used is approximately 4/3 of the geometric radius, which is the standard assumption for average atmospheric conditions.
| Station Type | Typical Height |
|---|---|
| Handheld Radio | 5 – 6 ft |
| Vehicle Mobile | 8 – 10 ft |
| Home Base | 25 – 35 ft |
| Small Tower | 50 ft |
| Tall Tower | 100 ft |
| Mountain Top | 500+ ft |
| Repeater | 500 – 2,000 ft |
| Example | Approx. LOS |
|---|---|
| Handheld to Handheld | 3 – 6 miles |
| Mobile to Mobile | 8 – 15 miles |
| Mobile to Base | 15 – 30 miles |
| Base to Base | 20 – 50 miles |
| Handheld to Repeater | 20 – 100+ miles |
| Mountain to Mountain | 100+ miles |
These are general examples only.
- Terrain
- Trees and vegetation
- Buildings
- Atmospheric conditions
- Antenna gain
- Feedline loss
- Transmitter power
- Receiver sensitivity
- Frequency band
- Fresnel zone clearance
Increasing antenna height generally provides greater improvement than increasing transmitter power.
For portable VHF/UHF operation, placing an antenna just a few feet higher often produces more noticeable improvement than doubling transmitter power.