ForHosting KIT · Developer Utilities

Subpanel feeder calculator

A subpanel needs a feeder sized for both the calculated load and the run length back to the main service panel.

● BetaFree · in your browser

Use it from WebAPIEmailTelegramApp soon

Undersize the wire and you risk overheating and nuisance trips; ignore distance and voltage drop can leave tools weak at the far end of a garage, barn, or addition. This subpanel feeder calculator takes the total load in amperes, the one-way distance in feet, and optional voltage, conductor material, phase count, continuous-load flag, and maximum voltage-drop percent. It applies a continuous-load factor when requested, selects the smallest table conductor with adequate 75 degree Celsius ampacity, pairs a standard breaker that covers design amperes without exceeding that ampacity, and upsizes the feeder when the approximate voltage-drop formula would exceed your target. The same pure arithmetic powers the free browser widget and the API, so interactive checks and automated takeoffs never disagree. Results are planning estimates for early design and education—not a substitute for a licensed electrician’s calculation under the electrical code adopted in your jurisdiction.

How to use it

Enter your values in the form above. The tool checks them before calculating and shows the result on the same page.

Check your inputs

Use the labels and units shown next to each field. If something is missing or outside the allowed range, the page points to the field to fix.

Use it again or automate it

Use the browser tool for individual checks and the API when you need the same capability in an automated workflow.

What you can do with it

Get an answer now

Enter one set of values and see the result without building a spreadsheet or script.

Compare scenarios

Change one value at a time and rerun the calculation to understand what affects the result.

Automate repeated work

Use the API when the same calculation needs to run inside your product or workflow.

FAQ

How do I use this capability?

Complete the fields above and run it on this page. The form highlights anything that needs attention.

For developers — API access

Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.

API endpoint

POSThttps://api.kit.forhosting.com/home/subpanel-feeder

Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.

Call it from your stack

curl -X POST https://api.kit.forhosting.com/home/subpanel-feeder \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"load_amps":60,"distance_ft":80}'

const res = await fetch("https://api.kit.forhosting.com/home/subpanel-feeder", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "load_amps": 60,
    "distance_ft": 80
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/home/subpanel-feeder",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "load_amps": 60,
    "distance_ft": 80
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/home/subpanel-feeder", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"load_amps":60,"distance_ft":80}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"load_amps":60,"distance_ft":80}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/home/subpanel-feeder", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "load_amps": 60,
  "distance_ft": 80
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "home.subpanel_feeder",
  "status": "queued",
  "_links": {
    "result": "/tasks/tsk_…/result"
  }
}

The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.

Pricing

Per request$0.002

Published price — no tokens, no invented credits. A failed task is never charged.

Errors

HTTP	Code	Meaning
`401`	`unauthorized`	Missing or invalid API key.
`402`	`insufficient_balance`	Your balance doesn't cover the task price.
`404`	`unknown_type`	That task type doesn't exist.
`429`	`rate_limited`	Too many requests. Use the webhook instead of polling.

Read the full KIT documentation →