WiFi Range Calculator
Estimate the maximum line-of-sight WiFi range from transmit power, antenna gains and receiver sensitivity using free-space path loss.
How it works
link budget = Tx + Gtx + Grx − sensitivity · FSPL = 20·log₁₀(d_km) + 20·log₁₀(f_MHz) + 32.44 · d = 10^((budget − 20·log₁₀(f) − 32.44) ÷ 20) km
The link budget is the total signal margin available: transmit power plus both antenna gains, minus the weakest signal the receiver can still read. Free-space path loss (FSPL) then says how quickly that margin is spent with distance and frequency — every doubling of range costs 6 dB, and higher frequencies lose more. Solving the FSPL equation for distance gives the theoretical maximum reach. Real range is always shorter because walls, interference, fading and non-line-of-sight paths add loss the free-space model ignores.
Worked example
A 20 dBm radio with 3 dBi antennas at each end and a −70 dBm sensitivity has a budget of 20 + 3 + 3 − (−70) = 96 dB. At 2400 MHz, distance = 10^((96 − 67.6 − 32.44)/20) ≈ 10^(−0.20) ≈ 0.63 km, so roughly 630 m in the open.
Sources: Free-space path loss — Wikipedia
Frequently asked questions
Why is my real WiFi range so much shorter?
Free-space path loss assumes a clear, unobstructed line of sight. Indoors, walls, floors, furniture and other 2.4/5 GHz devices add substantial loss and multipath fading, so practical indoor range is often a small fraction of this figure.
Does a higher frequency give more range?
No — for the same power, higher frequencies suffer more free-space loss, so 5 GHz reaches less far than 2.4 GHz. Higher bands trade range for more available spectrum and less congestion.
What is EIRP?
Effective Isotropic Radiated Power is transmit power plus antenna gain — the power actually radiated in the antenna’s best direction. Regulators cap EIRP, which is why big antenna gains may require you to reduce transmit power.
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This calculator is for educational purposes. Double-check important results before acting on them.