Wi-Fi Coverage and Dead Zone Calculator
ANA›Life Services Authority›National Calculator Authority›Wi-Fi Coverage and Dead Zone Calculator
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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.
Router Transmit Power (dBm)
Typical home routers: 17–23 dBm
Router Antenna Gain (dBi)
Built-in: 2–5 dBi; High-gain external: up to 15 dBi
Device Antenna Gain (dBi)
Smartphones/laptops: 0–2 dBi
Frequency Band
2.4 GHz (longer range, more interference) 5 GHz (faster, shorter range) 6 GHz (Wi-Fi 6E, shortest range)
Distance from Router (meters)
Environment / Obstacles
Open space (no walls) Light obstacles (1–2 drywall walls) Moderate (several interior walls) Heavy (concrete/brick walls, floors) Very heavy (metal structures, multiple floors)
Device Receiver Sensitivity (dBm)
Typical devices: −65 to −85 dBm (more negative = more sensitive)
Calculate
function wiCalc() { // --- Read inputs --- var txPower = parseFloat(document.getElementById('wi-tx-power').value); var txGain = parseFloat(document.getElementById('wi-tx-gain').value); var rxGain = parseFloat(document.getElementById('wi-rx-gain').value); var freq = parseFloat(document.getElementById('wi-frequency').value); var distance = parseFloat(document.getElementById('wi-distance').value); var envLoss = parseFloat(document.getElementById('wi-environment').value); var sensitivity = parseFloat(document.getElementById('wi-sensitivity').value);
// --- Validation --- var errors = []; if (isNaN(txPower) || txPower 30) errors.push("Transmit power must be 0–30 dBm."); if (isNaN(txGain) || txGain 20) errors.push("Router antenna gain must be 0–20 dBi."); if (isNaN(rxGain) || rxGain 10) errors.push("Device antenna gain must be −5 to 10 dBi."); if (isNaN(distance) || distance 500) errors.push("Distance must be 1–500 meters."); if (isNaN(sensitivity) || sensitivity > -40 || sensitivity 0) { resultDiv.style.display = 'block'; resultDiv.innerHTML = '⚠ ' + errors.join('⚠ ') + ''; return; }
// --- Free-Space Path Loss (FSPL) in dB --- // FSPL(dB) = 20·log10(d) + 20·log10(f) + 20·log10(4π/c) // Simplified: FSPL(dB) = 20·log10(d_m) + 20·log10(f_GHz) + 92.45 // (92.45 is the constant when d is in km and f in GHz; adjust for meters: // 20·log10(1/1000) = -60, so constant becomes 92.45 - 60 = 32.45) var fspl = 20 * Math.log10(distance) + 20 * Math.log10(freq) + 32.45;
// --- Received Signal Strength (RSS) --- // RSS(dBm) = TxPower(dBm) + TxGain(dBi) + RxGain(dBi) - FSPL(dB) - EnvLoss(dB) var rss = txPower + txGain + rxGain - fspl - envLoss;
// --- Link Margin --- // Link Margin = RSS - Sensitivity (positive = working connection) var linkMargin = rss - sensitivity;
// --- Maximum range (solve FSPL for d when RSS = sensitivity) --- // sensitivity = txPower + txGain + rxGain - FSPL_max - envLoss // FSPL_max = txPower + txGain + rxGain - sensitivity - envLoss // 20·log10(d_max) = FSPL_max - 20·log10(freq) - 32.45 var fsplMax = txPower + txGain + rxGain - sensitivity - envLoss; var log10dMax = (fsplMax - 20 * Math.log10(freq) - 32.45) / 20; var maxRange = Math.pow(10, log10dMax); // meters
// --- Coverage Area (circle) --- var coverageArea = Math.PI * maxRange * maxRange; // m² var coverageAreaSqFt = coverageArea * 10.7639;
// --- Signal Quality Classification --- var quality, qualityColor, qualityIcon; if (rss >= -50) { quality = "Excellent"; qualityColor = "#27ae60"; qualityIcon = "📶"; } else if (rss >= -60) { quality = "Good"; qualityColor = "#2ecc71"; qualityIcon = "📶"; } else if (rss >= -70) { quality = "Fair"; qualityColor = "#f39c12"; qualityIcon = "📶"; } else if (rss >= -80) { quality = "Weak"; qualityColor = "#e67e22"; qualityIcon = "⚠️"; } else if (rss >= sensitivity) { quality = "Very Weak (marginal)"; qualityColor = "#e74c3c"; qualityIcon = "⚠️"; } else { quality = "Dead Zone — No Connection"; qualityColor = "#c0392b"; qualityIcon = "❌"; }
var isDeadZone = rss '; html += 'Parameter' + 'Value';
html += 'Free-Space Path Loss (FSPL)' + '' + fmt(fspl,1) + ' dB';
html += 'Environmental / Obstacle Loss' + '' + envLoss + ' dB';
html += 'Received Signal Strength (RSS)' + '' + fmt(rss,1) + ' dBm';
html += 'Link Margin' + '' + fmt(linkMargin,1) + ' dB';
html += 'Signal Quality' + '' + qualityIcon + ' ' + quality + '';
html += 'Max Theoretical Range' + '' + (isFinite(maxRange) && maxRange > 0 ? fmt(maxRange,1) + ' m (' + fmt(maxRange*3.281,0) + ' ft)' : 'N/A') + '';
- html += 'Estimated Coverage Area'
- + ''
- + (isFinite(coverageArea) && coverageArea > 0
- ? fmt(coverageArea,0) + ' m² (' + fmt(coverageAreaSqFt,0) + ' ft²)'
- 'N/A') + '';
html += '';
// Dead zone / recommendation banner if (isDeadZone) { html += '' + '❌ Dead Zone Detected' + 'The received signal (' + fmt(rss,1) + ' dBm) is below your device's sensitivity threshold (' + sensitivity + ' dBm). No reliable connection is possible at this distance with these settings.' + ''; } else if (rss ' + '⚠ Weak Signal Warning' + 'Signal is marginal. Consider a Wi-Fi extender, mesh node, or repositioning the router.' + ''; } else { html += '' + '✅ Good Coverage' + 'Signal strength is adequate for reliable Wi-Fi at this distance.' + ''; }
// Signal bar visual var barPct = Math.min(100, Math.max(0, ((rss + 100) / 60) * 100)); // map -100...-40 dBm to 0-100% html += '' + 'Signal Strength Indicator' + '' + '' + '' + '−100 dBm (dead)−40 dBm (excellent)' + '';
resultDiv.style.display = 'block'; resultDiv.innerHTML = html; }
#### 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
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