Documentation sections

Signal-to-Noise Ratio (SNR) Calculator

POSThttps://rftools.io/api/py/v1/calculate

Slug snr-calculator. Calculate signal-to-noise ratio, noise floor, receiver sensitivity, and dynamic range for RF systems. Analyze your signal chain performance. Free, instant results.

Inputs

Send every one of these in inputs, in the units shown. Most are required: a call without one is refused (400) and costs nothing; one the calculator can do without takes the default shown. An input outside its range is still computed and flagged in the provenance.

Inputs of snr-calculator
Name	Unit	Range	Default	Description
bandwidthnumber	MHz	at least 0.001	1	Bandwidth
noiseFigurenumber	dB	at least 0	6	Noise Figure
signalPowernumber	dBm	−160 … 30	-60	Signal Power
temperaturenumber	K	at least 1	290	Temperature
targetSnrnumber	dB	−20 … 100	20	The signal-to-noise ratio the demodulator needs. The status fails below 10 dB.

Outputs

Returned in values, by key. A value that is unbounded or undefined is null.

Outputs of snr-calculator
Field	Unit	Description
snrheadline	dB	Signal-to-Noise Ratio
noiseFloor	dBm	Noise Floor
sensitivity	dBm	Receiver Sensitivity
dynamicRange	dB	Dynamic Range
thermalNoise	dBm	Thermal Noise (kTB)

Calling it

Calculate: one call, the request and response in full, and its errors.
Batch: this calculator with others, or a sweep, in one request.
Solve for a target: the value of one input that brings an output to a target.

curl -X POST https://rftools.io/api/py/v1/calculate \
  -H "X-API-Key: $RFTOOLS_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "slug": "snr-calculator",
    "inputs": {
      "bandwidth": 1,
      "noiseFigure": 6,
      "signalPower": -60,
      "temperature": 290,
      "targetSnr": 20
    }
  }'

import rftools

client = rftools.Client()  # reads RFTOOLS_API_KEY, or the key `rftools login` saved

result = client.calculate("snr-calculator", {
    "bandwidth": 1,
    "noiseFigure": 6,
    "signalPower": -60,
    "temperature": 290,
    "targetSnr": 20,
})
print(result.values)
print(result.warnings, result.provenance.formula_ref)

const response = await fetch("https://rftools.io/api/py/v1/calculate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.RFTOOLS_API_KEY,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "slug": "snr-calculator",
    "inputs": {
      "bandwidth": 1,
      "noiseFigure": 6,
      "signalPower": -60,
      "temperature": 290,
      "targetSnr": 20
    }
  }),
});
console.log(response.status, await response.json());

package main

import (
	"bytes"
	"fmt"
	"io"
	"net/http"
	"os"
)

func main() {
	body := []byte(`{
	  "slug": "snr-calculator",
	  "inputs": {
	    "bandwidth": 1,
	    "noiseFigure": 6,
	    "signalPower": -60,
	    "temperature": 290,
	    "targetSnr": 20
	  }
	}`)
	req, err := http.NewRequest("POST", "https://rftools.io/api/py/v1/calculate", bytes.NewReader(body))
	if err != nil {
		panic(err)
	}
	req.Header.Set("X-API-Key", os.Getenv("RFTOOLS_API_KEY"))
	req.Header.Set("Content-Type", "application/json")
	res, err := http.DefaultClient.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	out, _ := io.ReadAll(res.Body)
	fmt.Println(res.Status, string(out))
}

application/json

{
  "slug": "snr-calculator",
  "values": {
    "noiseFloor": -107.97518719422811,
    "snr": 47.97518719422811,
    "sensitivity": -97.97518719422811,
    "dynamicRange": 47.97518719422811,
    "thermalNoise": -113.97518719422811
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:snr-calculator",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "Friis, 'Noise Figures of Radio Receivers', Proc. IRE, 1944",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "bandwidth": {
          "min": 0.001,
          "max": null,
          "unit": "MHz"
        },
        "noiseFigure": {
          "min": 0,
          "max": null,
          "unit": "dB"
        },
        "signalPower": {
          "min": -160,
          "max": 30,
          "unit": "dBm"
        },
        "temperature": {
          "min": 1,
          "max": null,
          "unit": "K"
        },
        "targetSnr": {
          "min": -20,
          "max": 100,
          "unit": "dB"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "bandwidth": 1,
      "noiseFigure": 6,
      "signalPower": -60,
      "temperature": 290,
      "targetSnr": 20
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "bandwidth"
      ],
      "msg": "Input should be a valid number, unable to parse string as a number",
      "input": "abc"
    }
  ]
}

An input sent as text. Nothing was counted.

{
  "detail": "More than 120 requests in 60 seconds from this address.",
  "errorKind": "rate_limited",
  "limit": 120,
  "windowSeconds": 60,
  "upgradeUrl": "https://rftools.io/pricing/"
}

Too many requests in a minute, with Retry-After.

Same inputs on the calculator pageSignal-to-Noise Ratio (SNR) Calculator, at these values