FREE · NETWORK & IT INFRASTRUCTURE
Radio Link Budget Calculator.
Calculate free-space path loss, received signal, fade margin, Fresnel zone clearance and earth bulge for point-to-point wireless links.
- Free-space path loss
- 121.7 dB
- EIRP
- 42.5 dBm
- Received signal
- -56.7 dBm
- First Fresnel zone radius (midpoint)
- 8.04 m
- Earth bulge at midpoint
- 0.37 m
- Clearance needed above obstacles at midpoint
- 5.19 m 60 % of the Fresnel zone + earth bulge
- Maximum distance for 15 dB margin
- 7.32 km
- Free-space model: FSPL = 20 log₁₀(d km) + 20 log₁₀(f MHz) + 32.44. Real links lose more to obstacles, multipath and, above about 10 GHz, rain.
- EIRP and frequency limits are set by national regulators and differ between countries; check that your power and antennas are legal where you install them.
How to use Radio Link Budget Calculator
Enter frequency, distance, transmit power, antenna gains, cable losses and receiver sensitivity, plus other losses and the fade margin you want.
How it works
FSPL = 20 log₁₀(d) + 20 log₁₀(f MHz) + 32.44; received power = EIRP − FSPL + receive gain − losses. Clearance = 60 % of the first Fresnel zone + d² ÷ (8 k R).
Example
A 5 km link at 5.8 GHz with 20 dBm and 23 dBi antennas receives −56.7 dBm: an 18.3 dB margin, with 5.2 m clearance needed at midpoint.
Questions about Radio Link Budget Calculator
Is Radio Link Budget Calculator free, and do I need an account?
Yes. This tool is free to use in your browser without an account. Processing takes place on your device.
What are the limits and what should I check?
Free-space model: obstacles, multipath and rain fade above 10 GHz need site-specific planning. Legal power limits vary by country. Everything is calculated in your browser; nothing is sent or probed on the network. Review the result before using it in your work.
Is my input sent to a server?
Your input is processed in your browser and is not uploaded by this tool. Files and pasted text are cleared when the page is refreshed. Normal website requests are still required to load the page and its libraries. Read the privacy explanation.