Documentation sections

Conductor-to-Pad Maximum Width Calculator

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

Slug conductor-to-pad-width. Find the widest conductor that can reach a pad through the channel between its neighbours, from pad diameter, pitch and your fabricator’s minimum clearance.

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 conductor-to-pad-width
Name	Unit	Range	Default	Description
padDiameternumber	mm	0.05 … 10	0.6	Pad Diameter
neighbourPitchnumber	mm	0.1 … 10	1.27	Pitch to the Neighbouring Pad
minClearancenumber	mm	0.01 … 1	0.15	Your fabricator’s copper-to-copper minimum. This is a shop rule, not a constant.
conductorCountnumber	none	1 … 6	1	Conductors Through the Channel

Outputs

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

Outputs of conductor-to-pad-width
Field	Unit	Description
maxTraceWidthheadline	mm	Maximum Conductor Width
availableChannel	mm	Channel Between Pads
clearanceDemand	mm	One clearance to each pad plus one between each pair of conductors
utilisation	none	Channel Used by Copper
fits	none	1 when a conductor of non-zero width fits within the clearance rule

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": "conductor-to-pad-width",
    "inputs": {
      "padDiameter": 0.6,
      "neighbourPitch": 1.27,
      "minClearance": 0.15,
      "conductorCount": 1
    }
  }'

import rftools

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

result = client.calculate("conductor-to-pad-width", {
    "padDiameter": 0.6,
    "neighbourPitch": 1.27,
    "minClearance": 0.15,
    "conductorCount": 1,
})
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": "conductor-to-pad-width",
    "inputs": {
      "padDiameter": 0.6,
      "neighbourPitch": 1.27,
      "minClearance": 0.15,
      "conductorCount": 1
    }
  }),
});
console.log(response.status, await response.json());

package main

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

func main() {
	body := []byte(`{
	  "slug": "conductor-to-pad-width",
	  "inputs": {
	    "padDiameter": 0.6,
	    "neighbourPitch": 1.27,
	    "minClearance": 0.15,
	    "conductorCount": 1
	  }
	}`)
	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": "conductor-to-pad-width",
  "values": {
    "maxTraceWidth": 0.37000000000000005,
    "availableChannel": 0.67,
    "clearanceDemand": 0.3,
    "utilisation": 0.5522388059701493,
    "fits": 1
  },
  "warnings": [],
  "errors": [],
  "provenance": {
    "method": "calculator:conductor-to-pad-width",
    "version": "api@3f2c1a9b04de",
    "formulaRef": "IPC-2221B clearance practice; the clearance value itself is a fabricator rule and is an input here.",
    "assumptions": [],
    "validRange": {
      "status": "inside",
      "bounds": {
        "padDiameter": {
          "min": 0.05,
          "max": 10,
          "unit": "mm"
        },
        "neighbourPitch": {
          "min": 0.1,
          "max": 10,
          "unit": "mm"
        },
        "minClearance": {
          "min": 0.01,
          "max": 1,
          "unit": "mm"
        },
        "conductorCount": {
          "min": 1,
          "max": 6,
          "unit": ""
        }
      },
      "outside": [],
      "model": null
    },
    "computedAt": "2026-09-24T14:05:11.003Z",
    "inputs": {
      "padDiameter": 0.6,
      "neighbourPitch": 1.27,
      "minClearance": 0.15,
      "conductorCount": 1
    },
    "seed": null,
    "elapsedSeconds": 0.003
  }
}

{
  "detail": [
    {
      "type": "float_parsing",
      "loc": [
        "body",
        "inputs",
        "padDiameter"
      ],
      "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 pageConductor-to-Pad Maximum Width Calculator, at these values