Documentation sections

Intermodulation Distortion & IP3 Calculator

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

Slug intermodulation-distortion. Calculate IIP3, OIP3, IM3/IM2 products, and spurious-free dynamic range for RF amplifiers and mixers. Analyze two-tone spur frequencies. 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 intermodulation-distortion
Name	Unit	Range	Default	Description
outputPowernumber	dBm	any	10	Fundamental output power per tone in dBm
inputPowernumber	dBm	any	0	Input drive power per tone in dBm
oip3number	dBm	any	30	Output third-order intercept point from datasheet
oip2number	dBm	any	50	Output second-order intercept point. Higher = less IM2 distortion.
freq1number	MHz	at least 0.1	100	First test tone frequency for two-tone analysis
freq2number	MHz	at least 0.1	101	Second test tone frequency
bandLownumber	MHz	at least 0	88	Where the band the products must not reach starts: a receive band, or the channel you listen on
bandHighnumber	MHz	at least 0	108	Where the band ends

Outputs

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

Outputs of intermodulation-distortion
Field	Unit	Description
iip3	dBm	Input IP3 (IIP3)
im3Power	dBm	IM3 Product Power
im3Ratioheadline	dBc	IM3 to Carrier Ratio
dynamicRange	dB	Spurious-Free Dynamic Range
iip2	dBm	Input IP2 (IIP2)
im2Power	dBm	IM2 Product Power
im2Ratio	dBc	IM2 to Carrier Ratio
im3Low	MHz	IM3 Low (2f₁−f₂)
im3High	MHz	IM3 High (2f₂−f₁)
im2Sum	MHz	IM2 Sum (f₁+f₂)
im2Diff	MHz	IM2 Diff (\|f₁−f₂\|)
toneSpacing	MHz	Tone Spacing
productsInBand	none	Second- and third-order products and harmonics of the two tones that land inside the band, where no filter after the amplifier can remove them

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": "intermodulation-distortion",
    "inputs": {
      "outputPower": 10,
      "inputPower": 0,
      "oip3": 30,
      "oip2": 50,
      "freq1": 100,
      "freq2": 101,
      "bandLow": 88,
      "bandHigh": 108
    }
  }'

import rftools

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

result = client.calculate("intermodulation-distortion", {
    "outputPower": 10,
    "inputPower": 0,
    "oip3": 30,
    "oip2": 50,
    "freq1": 100,
    "freq2": 101,
    "bandLow": 88,
    "bandHigh": 108,
})
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": "intermodulation-distortion",
    "inputs": {
      "outputPower": 10,
      "inputPower": 0,
      "oip3": 30,
      "oip2": 50,
      "freq1": 100,
      "freq2": 101,
      "bandLow": 88,
      "bandHigh": 108
    }
  }),
});
console.log(response.status, await response.json());

package main

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

func main() {
	body := []byte(`{
	  "slug": "intermodulation-distortion",
	  "inputs": {
	    "outputPower": 10,
	    "inputPower": 0,
	    "oip3": 30,
	    "oip2": 50,
	    "freq1": 100,
	    "freq2": 101,
	    "bandLow": 88,
	    "bandHigh": 108
	  }
	}`)
	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": "intermodulation-distortion",
  "values": {
    "iip3": 20,
    "im3Power": -30,
    "im3Ratio": -40,
    "dynamicRange": 122.66666666666666,
    "iip2": 40,
    "im2Power": -30,
    "im2Ratio": -40,
    "im3Low": 99,
    "im3High": 102,
    "im2Sum": 201,
    "im2Diff": 1,
    "toneSpacing": 1,
    "productsInBand": 2
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:intermodulation-distortion",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "RF Microelectronics, 2nd ed., Behzad Razavi (2011), Chapter 2, section 2.2 — Effects of nonlinearity",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "outputPower": {
          "min": null,
          "max": null,
          "unit": "dBm"
        },
        "inputPower": {
          "min": null,
          "max": null,
          "unit": "dBm"
        },
        "oip3": {
          "min": null,
          "max": null,
          "unit": "dBm"
        },
        "oip2": {
          "min": null,
          "max": null,
          "unit": "dBm"
        },
        "freq1": {
          "min": 0.1,
          "max": null,
          "unit": "MHz"
        },
        "freq2": {
          "min": 0.1,
          "max": null,
          "unit": "MHz"
        },
        "bandLow": {
          "min": 0,
          "max": null,
          "unit": "MHz"
        },
        "bandHigh": {
          "min": 0,
          "max": null,
          "unit": "MHz"
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "outputPower": 10,
      "inputPower": 0,
      "oip3": 30,
      "oip2": 50,
      "freq1": 100,
      "freq2": 101,
      "bandLow": 88,
      "bandHigh": 108
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "outputPower"
      ],
      "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 pageIntermodulation Distortion & IP3 Calculator, at these values