Range and line-of-sight calculator
Enter the height of each antenna. You get the farthest distance the two can see each other over smooth earth, and how much open space the signal needs around the path.
What these numbers mean
Line-of-sight limit. The earth curves away under a straight radio path. The calculator uses the standard radio-horizon approximation with an effective earth radius of 4/3 the real one, which accounts for normal bending of radio waves in the lower atmosphere: distance in km ≈ 4.12 × (√h₁ + √h₂), with heights in meters. Real terrain, trees, and buildings usually cut this further. Hills can also extend it when one node sits high above the land in between.
Fresnel zone. A radio link needs more than a thin line of sight. The first Fresnel zone is a football-shaped region around the path, widest at the midpoint. Its radius is 17.32 × √(d / 4f) meters, where d is the path length in km and f is the frequency in GHz (0.915 for US Meshtastic). Planners commonly aim to keep at least 60% of that radius clear of obstacles.
Free-space path loss. This is how much the signal weakens over distance with nothing in the way: 20·log₁₀(d km) + 20·log₁₀(f MHz) + 32.44 dB. Real paths lose more because of obstructions and ground reflections. It helps you compare distances, but it doesn't predict a working link on its own.
For terrain-aware coverage maps, use the official Meshtastic Site Planner. For how presets, antennas, and placement affect range, read How far can Meshtastic reach?
Common questions
How far can Meshtastic reach?
It depends mostly on line of sight. Two handhelds at chest height on flat ground are limited to a few miles by the curve of the earth and by obstacles; nodes on rooftops, towers, or hills can link over much longer distances because their radio horizon is farther away.
Why does antenna height matter so much?
At 915 MHz, signals travel mostly in straight lines. Raising an antenna pushes the radio horizon out and lifts the path above trees, buildings, and terrain that block or weaken it.
What is the Fresnel zone?
It is a football-shaped region around the straight line between two antennas. A common rule of thumb in radio planning is to keep at least 60% of the first Fresnel zone clear of obstacles for a reliable link.