Wi-Fi Coverage and Dead Zone Calculator
Estimate your Wi-Fi signal strength at a given distance, effective coverage area, and whether a location is likely a dead zone — based on your router's transmit power, frequency band, antenna gain, and environment.
Formulas Used
Free-Space Path Loss (FSPL):
FSPL (dB) = 20·log₁₀(d) + 20·log₁₀(f) + 32.45
where d = distance in meters, f = frequency in GHz, and 32.45 is the constant for these units (derived from 20·log₁₀(4π/c) with unit adjustments).
Received Signal Strength (RSS):
RSS (dBm) = TxPower + TxGain + RxGain − FSPL − EnvironmentLoss
Link Margin:
Link Margin (dB) = RSS − ReceiverSensitivity
A positive link margin means a connection is possible; negative means a dead zone.
Maximum Range:
d_max (m) = 10^[(TxPower + TxGain + RxGain − Sensitivity − EnvLoss − 20·log₁₀(f) − 32.45) / 20]
Coverage Area:
Area (m²) = π · d_max²
(Assumes isotropic radiation in open space — a theoretical upper bound.)
Assumptions & References
- FSPL formula assumes line-of-sight propagation in free space (Friis transmission equation).
- Environmental loss values are empirical approximations: drywall ~3 dB/wall, concrete ~10–15 dB/wall, metal ~20–30 dB (IEEE 802.11 propagation studies).
- Coverage area assumes a circular, isotropic radiation pattern — real-world coverage is irregular.
- Signal quality thresholds: Excellent ≥ −50 dBm, Good −50 to −60, Fair −60 to −70, Weak −70 to −80, Very Weak below −80 dBm (Wi-Fi Alliance guidelines).
- Receiver sensitivity varies by device and protocol (802.11n/ac/ax); −75 dBm is a common conservative estimate.
- Does not account for multipath fading, interference from other networks, or beamforming.
- References: Friis (1946), IEEE 802.11-2020 standard, ITU-R P.1238 indoor propagation model.