Documentation sections

Three-Phase Power Calculator

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

Slug three-phase-power. Calculate three-phase real power (kW), reactive power (kVAR), apparent power (kVA), and power factor angle for wye or delta connections. Free 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 three-phase-power
Name	Unit	Range	Default	Description
connectionTypenumber	none	0 … 1	0	Connection TypeOne of: 0 Wye (star) · 1 Delta
lineVoltagenumber	V	at least 1	400	Line Voltage
currentnumber	A	at least 0	10	Line Current
powerFactornumber	none	0.01 … 1	0.85	Power Factor

Outputs

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

Outputs of three-phase-power
Field	Unit	Description
phaseVoltage	V	Phase Voltage
realPowerheadline	kW	Real Power
reactivePower	kVAR	Reactive Power
apparentPower	kVA	Apparent Power
pfAngle	°	Power Factor Angle

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": "three-phase-power",
    "inputs": {
      "connectionType": 0,
      "lineVoltage": 400,
      "current": 10,
      "powerFactor": 0.85
    }
  }'

import rftools

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

result = client.calculate("three-phase-power", {
    "connectionType": 0,
    "lineVoltage": 400,
    "current": 10,
    "powerFactor": 0.85,
})
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": "three-phase-power",
    "inputs": {
      "connectionType": 0,
      "lineVoltage": 400,
      "current": 10,
      "powerFactor": 0.85
    }
  }),
});
console.log(response.status, await response.json());

package main

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

func main() {
	body := []byte(`{
	  "slug": "three-phase-power",
	  "inputs": {
	    "connectionType": 0,
	    "lineVoltage": 400,
	    "current": 10,
	    "powerFactor": 0.85
	  }
	}`)
	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": "three-phase-power",
  "values": {
    "phaseVoltage": 230.94010767585033,
    "realPower": 5.888972745734183,
    "reactivePower": 3.6496575181789312,
    "apparentPower": 6.928203230275509,
    "pfAngle": 31.78833061705162
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:three-phase-power",
    "version": "api@3f2c1a9b04de",
    "formulaRef": null,
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "connectionType": {
          "min": 0,
          "max": 1,
          "unit": ""
        },
        "lineVoltage": {
          "min": 1,
          "max": null,
          "unit": "V"
        },
        "current": {
          "min": 0,
          "max": null,
          "unit": "A"
        },
        "powerFactor": {
          "min": 0.01,
          "max": 1,
          "unit": ""
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "connectionType": 0,
      "lineVoltage": 400,
      "current": 10,
      "powerFactor": 0.85
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "connectionType"
      ],
      "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 pageThree-Phase Power Calculator, at these values