Calculator Inputs
Use the responsive grid below. It shows three columns on large screens, two on medium screens, and one on mobile.
Signal Strength Plot
The graph compares predicted RSSI against receiver sensitivity and your target signal threshold across distance.
Example Data Table
This sample table uses the current calculator settings when available. Otherwise it uses the default scenario.
| Distance (m) | Predicted RSSI (dBm) | SNR (dB) | Link Margin (dB) | Link Status |
|---|---|---|---|---|
| 5 | -53.13 | 35.84 | 13.87 | Excellent |
| 10 | -62.76 | 26.21 | 4.24 | Very Good |
| 25 | -75.49 | 13.47 | -8.49 | Fair |
| 50 | -85.13 | 3.84 | -18.13 | Weak |
| 100 | -94.76 | -5.79 | -27.76 | Weak |
Formula Used
EIRP = Transmit Power + Transmit Antenna Gain − Transmit Loss
FSPL (dB) = 32.44 + 20 × log10(distance in km) + 20 × log10(frequency in MHz)
Environment Loss = 10 × (Path Loss Exponent − 2) × log10(distance in meters)
RSSI = Tx Power + Tx Gain + Rx Gain − Tx Loss − Rx Loss − Wall Loss − Misc Loss − FSPL − Environment Loss
Noise Floor = −174 + 10 × log10(channel bandwidth in Hz) + Noise Figure
SNR = RSSI − Noise Floor
Link Margin = RSSI − Receiver Sensitivity
This calculator uses a practical planning model. Real environments can still vary because of reflections, roaming behavior, interference, and client hardware limits.
How to Use This Calculator
- Enter your radio transmit power, antenna gains, and cable losses.
- Set the WiFi frequency and real separation distance in meters.
- Add wall, obstacle, and miscellaneous attenuation estimates.
- Choose a path loss exponent that matches the environment.
- Provide bandwidth, receiver noise figure, sensitivity, and fade margin target.
- Press Calculate Signal Strength to show results above the form.
- Review RSSI, SNR, link margin, quality, and the plotted distance curve.
- Export the summary with the CSV or PDF download buttons.
Frequently Asked Questions
1) What does RSSI mean in this calculator?
RSSI is the predicted received signal strength at the client or remote radio. It is shown in dBm, where values closer to zero are stronger. A signal around −55 dBm is usually very strong, while −80 dBm is often weak.
2) Why is SNR important?
SNR compares the received signal to the noise floor. A stronger signal is not enough if noise is also high. Better SNR usually supports faster modulation, fewer retries, and more stable WiFi performance.
3) What does the path loss exponent control?
It adjusts how quickly signal strength falls as distance increases in real environments. Open areas are closer to 2.0. Offices, homes, and dense indoor spaces usually need larger values because walls and clutter increase attenuation.
4) Why add wall loss separately?
Path loss exponent handles general environmental decay. Wall loss lets you include specific obstacles like drywall, brick, glass, or concrete. This makes the estimate more realistic for indoor layouts and multi-room coverage planning.
5) What is receiver sensitivity?
Receiver sensitivity is the minimum signal level needed for a selected data rate or modulation. If predicted RSSI stays above that threshold, the link is more likely to work well. Higher-speed modes usually require stronger signals.
6) Does higher transmit power always improve WiFi?
Not always. More power may help downlink coverage, but client devices still need enough uplink power to answer. Excessive power can also worsen cell overlap, roaming behavior, and interference in dense deployments.
7) Why can 2.4 GHz reach farther than 5 or 6 GHz?
Lower frequencies generally experience less path loss at the same distance. They also penetrate obstacles better in many indoor scenarios. That is why 2.4 GHz often reaches farther, although it can be more crowded and slower.
8) Why can actual speed differ from this estimate?
Actual throughput depends on channel congestion, interference, roaming decisions, client radio quality, MIMO capability, protocol overhead, and retransmissions. This calculator estimates signal behavior and link headroom, not exact application-level speed.