RF calculator
RF link budget calculator
Estimate EIRP, free-space path loss, and received power from a transparent RF link budget.
Need this in code or an AI agent? Call it as a free API.
Reading the result
EIRP combines transmitter output, transmit-antenna gain, and transmitter-side cable loss. Received power then subtracts path and other losses and adds receive-antenna gain.
The result is not a coverage threshold. Compare it with the receiver sensitivity and the margin required for the intended modulation, reliability, fading, and environmental variation.
What is not included
The calculator uses free-space path loss. Walls, foliage, diffraction, multipath, interference, polarization mismatch, connector variation, and regulatory limits require separate treatment.
For the building-model workflow, see Calculate and read RF coverage.
What this doesn't model
- Walls and floors between the radios. Received power here assumes free space.
- Fade margin, receiver sensitivity, interference, and channel overlap.
A SiteRF project applies the radio settings you chose to a floor plan with its wall materials, and reports coverage as a map and a report you can hand over.
Related free tools
Free API
RF link budget as an API
The same calculation over HTTP. Send the parameters in the query string or as JSON and get the result back with its formula and assumptions.
No API key. GET or POST. Every result carries its formula, assumptions, and source.
Request
curl -G "https://siterfapp.com/api/v1/tools/link-budget" \
-d transmit_power_dbm=20 \
-d transmit_gain_dbi=4 \
-d receive_gain_dbi=0 \
-d cable_loss_db=1 \
-d other_loss_db=0 \
-d distance=10 \
-d distance_unit=m \
-d frequency=5.5 \
-d frequency_unit=GHzResponse (abridged)
{
"tool": "link-budget",
"inputs": {
"transmit_power_dbm": 20,
"transmit_gain_dbi": 4,
"receive_gain_dbi": 0,
"cable_loss_db": 1,
"other_loss_db": 0,
"distance": 10,
"distance_unit": "m",
"frequency": 5.5,
"frequency_unit": "GHz"
},
"result": {
"eirp_dbm": 23,
"path_loss_db": 67.25503701176825,
"received_power_dbm": -44.25503701176825
},
"next_steps": [
{
"id": "rf_solve_coverage",
"why": "Received power here assumes free space: walls and floors between the radios are not modelled. Whole-building coverage needs a floor plan.",
"requires": "account_with_approval",
"status": "available",
"learn_more": "https://siterfapp.com/agents/#rf_solve_coverage"
}
]
}