link calculator ubnt

How this UBNT link calculator helps

If you are planning a Ubiquiti point-to-point backhaul, you need more than just line of sight. A reliable wireless bridge depends on a healthy link budget: transmit power, antenna gain, path loss, receiver sensitivity, and realistic environmental losses all matter. This calculator gives you a fast first-pass estimate before you install hardware on rooftops or towers.

It is designed for common UBNT planning workflows where you want to answer practical questions quickly: Will this link work at all? How much fade margin do I have? Do I need bigger antennas or shorter distance?

What the calculator computes

1) Free-Space Path Loss (FSPL)

FSPL models how much signal weakens as it travels through space. The tool uses:

FSPL (dB) = 92.45 + 20 log₁₀(distance in km) + 20 log₁₀(frequency in GHz)

2) EIRP and received signal level

Effective isotropic radiated power (EIRP) is estimated from TX power + TX antenna gain - TX losses. Then received level is computed by subtracting path loss and adding RX antenna gain minus RX losses and other losses.

3) Fade margin

Fade margin is the difference between calculated received signal and receiver sensitivity. Bigger fade margin means better weather tolerance and better stability over time.

Input tips for accurate results

• Distance: Use real path length, not just map straight-line guesses if terrain forces offset mounting.
• Frequency: Match your radio band (2.4, 5, 6, 11, 24 GHz, etc.).
• Antenna gain: Use the actual dish/panel value from the model datasheet.
• Losses: Include connectors, pigtails, and a realistic interference/rain budget.
• Sensitivity: Sensitivity changes by modulation rate; use the target throughput mode, not the most optimistic value.

How to interpret link quality status

• Excellent: fade margin ≥ 20 dB (good resilience for changing conditions)
• Good: fade margin 10–19.9 dB (normally stable with proper alignment)
• Marginal: fade margin 3–9.9 dB (works, but likely to drop MCS in bad conditions)
• Poor: fade margin < 3 dB (high risk of instability or outage)

Practical UBNT planning checklist

Before installation

• Validate unobstructed line of sight and at least 60% Fresnel clearance.
• Pick channel width based on interference conditions, not only top speed goals.
• Confirm local regulatory EIRP limits.

During alignment

• Use built-in alignment tone/GUI and adjust both azimuth and elevation slowly.
• Watch chain balance on dual-polarity radios.
• Record RSSI and modulation values once the link stabilizes.

After deployment

• Monitor CCQ, retransmissions, and capacity over a full day cycle.
• Re-check alignment after severe wind events.
• Keep firmware current and document final antenna heights and aiming angles.

Common mistakes this calculator can prevent

• Assuming “line of sight” automatically means a reliable link.
• Ignoring connector and cable losses on each side.
• Using sensitivity numbers from a low-rate mode while expecting high throughput.
• Underestimating the impact of interference in dense 5 GHz environments.

Final note

This page is a planning calculator, not a replacement for full RF survey tools. Use it for quick feasibility checks, then validate with terrain profiles, spectrum analysis, and on-site testing. For most UBNT deployments, combining a good link budget with clean channels and precise alignment is the fastest route to stable performance.