VHF Radio Range Calculator
Reviewed by Hamza Gujjar, Algorithm Architect & Software Developer
Last updated: July 27, 2026VHF Radio Range Calculator
Marine VHF radio is a line-of-sight communication system - effective range depends fundamentally on antenna height, not transmitter power, since VHF signals don't reliably bounce over the horizon the way HF/SSB signals sometimes can.
Range (nm) per antenna = 1.42 × √(Antenna Height in feet)
Total Range = Range from Antenna 1 + Range from Antenna 2
Example
A 10 ft boat antenna communicating with a 100 ft shore tower:
Range 1 = 4.49 nm, Range 2 = 14.2 nm → Total Range ≈ 18.7 nautical miles
Why Antenna Height Matters More Than Power
Because VHF range is fundamentally a radio-horizon (line-of-sight) limitation rather than a signal-strength limitation, a taller antenna meaningfully extends usable range in a way that simply switching to a more powerful radio transmitter cannot match - this is exactly why boaters and marinas invest in taller antenna mounts and why shore-based repeater towers are built as tall as practically possible.
A Practical Planning Tool
This calculation is useful for estimating realistic communication range between your vessel and a marina, another boat, or a Coast Guard station before heading out, helping set realistic expectations for when you'll lose direct radio contact during a passage.