FPV Video Range Calculator
Estimate FPV video transmission range based on transmitter power and antenna gain.
Calculate theoretical line-of-sight distance.
The Friis transmission equation
FPV range is governed by a 1946 RF formula that any physics student would recognize:
range = (c ÷ (4π × f)) × √(P_tx × G_tx × G_rx ÷ S_rx)
Translated to the working form most calculators use:
free-space path loss (dB) = 20 × log₁₀(distance_m) + 20 × log₁₀(frequency_MHz) + 32.45
The link budget is:
EIRP + receive antenna gain − receiver sensitivity = maximum allowable path loss
Solve for distance and you get a theoretical range. In open air with no obstacles and perfect antenna alignment, the formula is accurate within a few percent.
Why real range is always lower
Free-space assumes nothing absorbs or reflects the signal. The real world is full of trees (each costs 1 to 3 dB at 5.8 GHz), buildings (10+ dB through brick), water in the air (0.1 dB/km at 5.8 GHz, much more at 24 GHz), and reflected interference (multipath fading). Plan for 30 to 60% of the calculated theoretical range as your usable range, less in dense terrain.
Common FPV combinations
| Setup | TX power | TX gain | RX gain | Theoretical range |
|---|---|---|---|---|
| Cinewhoop indoor | 25 mW | 2 dBi | 2 dBi | ~250 m |
| Freestyle quad | 200 mW | 2 dBi | 11 dBi | ~3 km |
| Long range | 1000 mW | 2 dBi | 14 dBi | ~10 km |
| HD digital (DJI O3) | 700 mW | 2 dBi | varies | ~8 km |
Antenna polarization matters
Linear-to-linear (dipole-to-dipole) antennas at perfect alignment work great. Mismatch the polarization by 90° and you lose 20 dB, about 90% of your range. Most FPV systems use circular polarization (RHCP or LHCP) on both ends, which trades 3 dB for orientation-independence. Mixing RHCP with LHCP is catastrophic; check both ends use the same handedness.
Local power limits
Most countries cap FPV transmit power: 25 mW for 5.8 GHz analog in the EU under EN 300 440 unrestricted, 200 mW in many countries with a HAM license, and up to 1000 mW in some jurisdictions. Always check your local rules before turning the dial up.