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Network Bandwidth Coverage Radius Calculator

This calculator estimates an idealized wireless coverage radius from a simple free-space link budget. It combines transmit power, antenna gains, receiver sensitivity, system losses, fade margin, and carrier frequency to determine the maximum path loss and corresponding line-of-sight distance.

The result can support early feasibility checks for point-to-area or point-to-point wireless planning when only basic radio parameters are known. Buildings, foliage, terrain, diffraction, interference, cable losses not entered here, antenna height, and local regulations can materially reduce practical range, so a site survey or propagation model is needed for deployment decisions.

Radio link inputs

MHz
dBm
dBi
dBi
dBm
dB
dB
Result
—
Idealized free-space coverage radius
Maximum path loss—
Coverage diameter—
Idealized coverage area—
Free-space model—

1. Enter the carrier frequency

Use the operating frequency in MHz. Frequency affects free-space path loss directly.

2. Build the transmit side

Enter transmitter output power and transmit antenna gain in the indicated logarithmic units.

3. Enter receiver capability

Provide receive antenna gain and the receiver sensitivity threshold associated with the intended data rate or modulation.

4. Subtract losses and margin

Add cable or implementation losses not already captured elsewhere and choose a fade margin for uncertainty.

5. Review the idealized radius

Treat the distance as a free-space ceiling for the entered link budget, then refine it with a propagation model or site survey for real deployment.

The calculator first determines how much free-space path loss the link can tolerate, then solves the standard FSPL relationship for distance.

Maximum path loss = Pt + Gt + Gr − L − M − Sr FSPL(dB) = 32.44 + 20 log10(fMHz) + 20 log10(dkm) dkm = 10^[(Maximum path loss − 32.44 − 20 log10(fMHz)) ÷ 20]

Pt is transmit power in dBm, Gt and Gr are antenna gains in dBi, L is other system loss in dB, M is fade margin in dB, Sr is receiver sensitivity in dBm, fMHz is frequency in MHz, and dkm is distance in kilometers.

This free-space model assumes unobstructed propagation. It does not include clutter, diffraction, multipath, terrain, Fresnel-zone blockage, antenna height effects, or interference.

What the result means

Use the result as a planning estimate based on the values entered. Compare it with measured performance or system-specific engineering limits before making a deployment decision.

Changing any input updates the result automatically; Reset restores the example defaults shown on this page.

Given: 3500 MHz, 30 dBm transmit power, 8 dBi transmit gain, 2 dBi receive gain, -92 dBm sensitivity, 5 dB losses, and 12 dB fade margin.

Calculation: Maximum path loss = 30 + 8 + 2 − 5 − 12 − (-92) = 115.00 dB. Distance = 10^((115.00 − 32.44 − 20 log10(3500)) ÷ 20) = 3.836 km.

Result: The free-space link-budget radius is approximately 3.836 km. Real-world range is typically constrained further by the environment and installation geometry.

Why is this called an idealized radius?

The calculation uses free-space path loss, which assumes a clear unobstructed propagation path. Real environments introduce additional losses that can reduce range substantially.

What receiver sensitivity should I enter?

Use the sensitivity associated with the data rate, channel bandwidth, modulation, or packet-performance threshold you need. A lower numeric value in dBm, such as −95 dBm instead of −85 dBm, represents a more sensitive receiver.

Should cable loss be included in system losses?

Yes, if it is not already reflected in the transmit power, antenna gain, or receiver figures you enter. Avoid subtracting the same loss twice.

What does fade margin do to the result?

Fade margin deliberately reduces the path loss available for distance, leaving budget for fading and uncertainty. Increasing the margin therefore decreases the calculated radius.

Can this replace a coverage survey or terrain model?

No. It is a first-pass link-budget calculation. Buildings, foliage, terrain, antenna heights, Fresnel clearance, interference, and regulatory constraints need a more detailed propagation analysis.