Wireless Link Budget Calculator
Estimate received signal strength, path loss, and link margin for a point-to-point RF link.
What is a link budget?
A link budget is an accounting of all gains and losses from a transmitter to a receiver. In plain language, it tells you whether your wireless signal will still be strong enough when it arrives at the far end of the link.
Engineers use link budgets for Wi-Fi backhaul, microwave links, telemetry, satellite communications, IoT networks, and any radio system where reliability matters. A good link budget helps prevent dropped connections, unstable throughput, and expensive field rework.
Core link budget equation
The calculator above uses a common free-space model. The main equations are:
- FSPL (dB) = 32.44 + 20 log10(f in MHz) + 20 log10(d in km)
- EIRP (dBm) = TX Power + TX Antenna Gain − TX Losses
- Received Power (dBm) = EIRP − FSPL + RX Antenna Gain − RX Losses − Other Losses
- Link Margin (dB) = Received Power − Receiver Sensitivity
If link margin is higher than your required fade margin, your link is generally in good shape for real-world conditions.
How to use this calculator
1) Enter radio and antenna parameters
Start with transmit power, antenna gains, and cable/connector losses. Use realistic values from datasheets or measured installation losses.
2) Set distance and frequency
Longer distances and higher frequencies increase path loss. Even small frequency changes can noticeably affect your budget over long links.
3) Add implementation losses
The Other Losses field can include polarization mismatch, rain fade estimate, foliage loss, radome loss, and pointing error allowances.
4) Compare against sensitivity and target margin
Receiver sensitivity depends on data rate, modulation, coding, and bandwidth. Always match the sensitivity to the mode you intend to operate.
Interpreting the results
- Free-Space Path Loss: The unavoidable spreading loss of the signal over distance.
- EIRP: Effective radiated power after TX chain gains and losses.
- Received Power: Expected signal level at the receiver input.
- Link Margin: Safety cushion above sensitivity. More margin usually means better uptime.
- Maximum Theoretical Distance: A rough distance estimate for your chosen required margin under free-space assumptions.
Design tips for stronger RF links
Increase antenna gain carefully
Higher-gain antennas can dramatically improve link margin, but they narrow beamwidth. That means tighter alignment and more sensitivity to tower movement.
Reduce avoidable losses
Shorter cable runs, better connectors, and quality installation practices often provide “free dB” improvements with no spectrum impact.
Plan for weather and interference
Real deployments are not pure free-space. Leave adequate margin for rain, multipath, interference, and seasonal vegetation changes.
Validate with field data
Use this calculator during planning, then verify with on-site signal measurements, throughput tests, and long-term monitoring.
Common mistakes to avoid
- Using sensitivity for the wrong modulation/coding profile.
- Ignoring cable, connector, or branching losses.
- Forgetting legal EIRP limits in your region.
- Assuming line-of-sight is enough without Fresnel clearance.
- Designing with near-zero fade margin and expecting carrier-grade uptime.
Final thought
A link budget calculator is one of the fastest ways to de-risk a wireless project. With realistic assumptions and a healthy fade margin, you can turn a “maybe it works” link into a predictable, resilient communication path.