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RF tools
Free, browser-based calculators for radio work: link planning, atmospheric losses, antennas, feedline loss, unit conversion, noise and radar. A hiking & outdoor set for horizon distance, summit bearings and walking time sits at the end of the page. Every tool computes as you type, draws what it computes, and explains the formula behind the result with a worked example and cited sources. No account, no install.
45 tools
Link planning
Will the link work? Path loss, clearance and horizon distance — before you touch a map.
Free-space path loss calculator
Signal loss over distance for any frequency, from the FSPL formula.
Fresnel zone calculator
First Fresnel zone radius and the 60% clearance rule for link paths.
Radio horizon calculator
How far a signal reaches over smooth earth, from antenna height.
Earth bulge calculator
Height the Earth’s curvature adds mid-path, with k-factor refraction.
Link budget calculator
Received power and fade margin from TX power, gains, losses and path loss.
LoRa airtime calculator
Time on air, duty-cycle limits and data rate from spreading factor, bandwidth and payload.
Satellite look angle calculator
Azimuth, elevation and slant range to a geostationary satellite from your location.
Knife-edge diffraction calculator
Extra loss when a ridge or roof cuts into the path, from the ITU-R P.526 single-edge model.
LoRa / Meshtastic range calculator
Maximum link distance from spreading factor, TX power, antennas and heights: free space, ground and horizon limits.
Walkie-talkie range calculator
How far two handhelds really reach (PMR446, FRS, GMRS, ham HTs) from height, power and terrain type.
Atmosphere & environment losses
What rain, air, clouds, walls, clutter and trees cost on top of free space: the ITU-R methods, with the formula shown.
Rain attenuation calculator (ITU-R P.838)
Specific rain attenuation in dB/km from frequency, rain rate and polarisation, and the loss over your path length.
Atmospheric gas attenuation calculator (ITU-R P.676)
Oxygen and water-vapour absorption in dB/km from 1 to 1000 GHz for your pressure, temperature and humidity, and the loss over a terrestrial path.
Cloud and fog attenuation calculator (ITU-R P.840)
Attenuation in fog or cloud in dB/km from frequency, temperature and liquid-water density, and the slant-path loss through a cloud layer.
Clutter loss calculator (ITU-R P.2108)
The extra loss from buildings and trees around a terminal: the statistical terrestrial and earth-space models and the height-gain correction.
Building entry loss calculator (ITU-R P.2109)
How much signal is lost entering a traditional or thermally efficient building, by frequency, elevation angle and probability.
Vegetation attenuation calculator (ITU-R P.833)
The loss of a path that ends inside woodland, from frequency and depth of vegetation, with the saturation the model predicts.
Antennas
Element lengths and aiming, from wire dipoles to sector downtilt.
Antenna downtilt calculator
Tilt angle and ground footprint from antenna height and target distance.
Dipole length calculator
Half-wave dipole element lengths for any frequency.
Parabolic dish gain calculator
Gain, beamwidth and effective aperture of a dish from diameter, frequency and efficiency.
Antenna beamwidth ↔ gain calculator
Estimate gain from the two half-power beamwidths, or the beamwidth a given gain implies.
Quarter-wave vertical calculator
Radiator and radial lengths for a ground-plane vertical at any frequency.
Transmitter & feedline
What really leaves the antenna after cables, connectors and mismatch take their share.
EIRP calculator
Radiated power from TX power, cable loss and antenna gain — with regulatory limits.
VSWR calculator
Convert VSWR, return loss, reflection coefficient and mismatch loss.
Coax cable loss calculator
Feedline attenuation for common coax types, by length and frequency.
Attenuator pad calculator
Resistor values for pi and tee attenuators at any dB and impedance, with power ratings.
Skin depth calculator
How deep RF current flows in copper, aluminium and other metals: skin depth and surface resistance by frequency.
RF exposure distance calculator
Safe distance from an antenna for FCC and ICNIRP exposure limits, from power, gain and frequency.
Units & spectrum
Fast conversions between the units RF work actually uses.
dBm ↔ watt converter
Convert between dBm, milliwatts and watts, with common reference levels.
Frequency ↔ wavelength calculator
λ = c / f, with the ITU band for any frequency.
Wi-Fi channel to frequency converter
Center frequencies and widths for 2.4, 5 and 6 GHz channels.
Field strength converter
dBµV/m, V/m, power density and received dBm, converted at any frequency and antenna gain.
Radar and radio frequency band designations
Which band any frequency is in: IEEE radar letters (L, S, C, X, Ku, K, Ka, V, W), ITU band numbers and NATO letters.
Signal & noise
What the receiver can actually hear, and why.
Radar
Range, resolution, Doppler and reflectivity: the arithmetic behind every radar, from speed guns to weather radar.
Radar range equation calculator
Maximum detection range from power, antenna gain, RCS and receiver sensitivity, with the R⁴ rule: double the range costs 16× the power.
Radar horizon calculator
How far a radar sees a ship or aircraft over the curved earth, and the lowest altitude it can see at a given range.
PRF calculator: unambiguous range, blind speeds and duty cycle
Maximum unambiguous range and velocity, blind speeds, blind range, duty cycle and average power from PRF, frequency, pulse width and peak power.
Radar resolution calculator
Range resolution from pulse width or bandwidth, cross-range resolution from beamwidth or antenna size.
FMCW radar calculator
Chirp bandwidth, slope and ADC rate → range resolution, beat frequency, maximum range and velocity for mmWave sensors.
Radar cross section (RCS) calculator: m² ↔ dBsm
Convert RCS between m² and dBsm, compare with birds, people, cars and ships, and compute spheres, plates and corner reflectors.
Weather radar dBZ to rain rate converter
Convert dBZ to mm/h and back with Marshall–Palmer, the NEXRAD default or the tropical Z–R relation.
Beyond radio
Four calculators for the outdoor questions our viewshed users ask. No radio knowledge needed.
Hiking & outdoor
Summits, horizons and trails: how far you can see, which peak is which, whether a ridge blocks the sky and how long the walk takes.
How far can you see? Horizon distance calculator
Distance to the horizon from any height, and how much of a distant peak or ship the curve hides.
Distance & bearing calculator
Great-circle distance, bearing and elevation angle between two coordinates, summit to summit.
Horizon mask calculator (ridge elevation angle)
The elevation angle a ridge blocks, and whether GPS, satellite messengers or a GEO satellite still clear it.
Hiking time calculator
Walking time from distance, ascent and descent by Naismith, Tranter, DIN 33466 and the Swiss signpost formula, with breaks.
FAQ
- Are these RF calculators free?
- Yes. Every tool on this page is free, runs entirely in your browser and works without an account — the same terms as the Waveshed coverage simulator itself.
- How are the results computed?
- Each tool implements the standard published formula and shows it on the page, together with a step-by-step explanation, a worked example and the sources it is based on — ITU recommendations, regulatory texts and reference literature. Nothing is a black box.
- What if I need more than a formula?
- Formulas assume idealized geometry. When terrain decides the outcome, run a free line-of-sight or RF coverage simulation on real elevation data — directly in the browser, on the Waveshed map.
Formulas get you to a first estimate. For the real thing — terrain-aware line-of-sight and RF coverage on a live map — the Waveshed simulator is free too.
Open the simulator →