Calculator Inputs
Example Data Table
| Scenario | Frequency | Distance | Transmit Power | Antenna Gains | Total Loss | Receiver Sensitivity | Estimated Received Power | Simple Margin |
|---|---|---|---|---|---|---|---|---|
| Small campus link | 2400 MHz | 1 km | 20 dBm | 12 / 12 dBi | 3 dB | -82 dBm | -59.04 dBm | 22.96 dB |
| Building bridge | 5000 MHz | 3 km | 23 dBm | 18 / 18 dBi | 4 dB | -75 dBm | -60.96 dBm | 14.04 dB |
| Long outdoor backhaul | 5800 MHz | 10 km | 27 dBm | 24 / 24 dBi | 5 dB | -85 dBm | -57.72 dBm | 27.28 dB |
Formula Used
Free Space Path Loss
FSPL dB = 32.44 + 20 log10(distance in km) + 20 log10(frequency in MHz)
Received Power
Received Power dBm = Tx Power + Tx Gain + Rx Gain - Total Loss - FSPL
Total Loss
Total Loss dB = Tx Cable Loss + Rx Cable Loss + Connector Loss + Miscellaneous Loss
Noise Floor
Noise Floor dBm = -174 + 10 log10(channel bandwidth in Hz) + Noise Figure
Signal To Noise Ratio
SNR dB = Received Power - Noise Floor
Available Fade Margin
Available Fade Margin dB = Received Power - Design Threshold
Maximum Distance
Maximum Distance is solved from the FSPL formula after subtracting the target fade margin.
Fresnel Radius
Fresnel Radius m = 17.32 × square root of d1 × d2 divided by frequency GHz × total distance.
Finance Formulas
Initial Cost = Base Cost + Contingency Cost. First Year Cost = Initial Cost + twelve monthly costs.
How To Use This Calculator
- Enter the wireless frequency and distance between both sites.
- Add transmit power, antenna gains, and all expected losses.
- Enter receiver sensitivity, bandwidth, noise figure, and required SNR.
- Add antenna heights and midpoint obstacle height for clearance review.
- Add cost values to estimate the project budget.
- Press the calculate button.
- Review received power, fade margin, clearance margin, and cost output.
- Use CSV or PDF export for planning notes and client reports.
WiFi Link Budget Planning Guide
Why link budgeting matters
A wireless link budget turns guesses into measurable choices. It compares transmitted power, antenna gain, path loss, cable loss, receiver sensitivity, and safety margin. The result shows whether a radio link can survive distance, weather, interference, and installation loss. A strong budget also supports purchasing decisions. Teams can compare antennas, radios, mounting heights, and labor costs before buying equipment.
Core planning factors
Distance and frequency create free space path loss. Higher frequency links usually lose more signal across the same distance. Antenna gain helps focus energy toward the remote site. Cable and connector losses reduce useful power. Receiver sensitivity defines the weakest signal the radio can decode. Fade margin adds reserve power for rain, multipath, trees, alignment errors, and future noise.
Finance view for projects
A WiFi budget is not only an engineering check. It also guides project cost control. A link may pass technically while using expensive antennas or tall mounts. Another option may pass with lower cost and enough margin. This calculator includes equipment, installation, site, monthly, and contingency fields. Cost per Mbps helps compare designs in business terms.
Clearance and reliability
Outdoor links need Fresnel clearance. The first Fresnel zone is the signal space around the direct path. Objects inside that zone can reduce strength even when both antennas can see each other. A common planning rule keeps at least sixty percent clear. Earth curvature also matters on longer paths. The clearance estimate helps decide antenna height and tower needs.
How to read results
Positive fade margin means the received signal is stronger than the chosen threshold. Larger margin is safer. Negative margin means the link needs improvement. Increase antenna gain, reduce cable loss, shorten distance, raise antenna height, or choose better radios. Check local power limits before increasing transmit power. Use the maximum distance result as a planning guide, not a promise. Real sites still need surveys, alignment, and interference testing.
Practical use tips
Run several scenarios before final approval. Change distance, gain, cable length, and labor cost. Save the result as CSV for records. Download a PDF summary for proposals. Keep assumptions visible. This makes reviews faster and helps avoid missed expenses during installation and testing.
FAQs
What is a WiFi link budget?
It is a signal accounting method. It adds transmit power and antenna gains. It subtracts path loss, cable loss, connector loss, and extra losses. The final value estimates received signal strength.
Why is fade margin important?
Fade margin is reserve signal power. It helps the link handle rain, reflections, foliage, alignment errors, and interference. More margin usually means better reliability.
What is a good fade margin?
Many outdoor links use 15 dB to 25 dB as a planning target. Critical links may need more. The correct value depends on reliability needs, climate, distance, and interference.
Does higher antenna gain always help?
Higher gain can improve received signal. It also narrows beam width and may require better alignment. It can also affect legal EIRP limits, so check local rules.
What is receiver sensitivity?
Receiver sensitivity is the weakest signal a radio can decode at a specific data rate. Faster data rates usually need stronger received signals.
Why does frequency affect path loss?
Higher frequencies have greater free space path loss for the same distance. This is why a 5 GHz link usually needs more gain than a similar 2.4 GHz link.
What does Fresnel clearance mean?
Fresnel clearance is open space around the direct signal path. Obstacles inside this space can reduce signal quality, even when there is visual line of sight.
Can this replace a site survey?
No. This calculator supports planning only. Real installations still need spectrum checks, physical inspection, mounting review, alignment, and performance testing.