ForHosting KIT · Developer Utilities

Amp to wire size calculator

Choosing a wire gauge from current alone is how low-voltage projects end up with dim lights, hot cables and unhappy inspectors.

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

The correct size depends on three things working together: how many amperes the load draws, how far the power has to travel, and how much voltage drop you can tolerate along the way. This API turns amps into a wire size the way an electrician does: enter the current draw in amperes, the one-way run length in feet or meters, your system voltage — 12, 24, 48, 120, 230 V or any other — and the voltage drop limit you accept, either as a percentage of the system voltage (3% by default) or as an absolute value in volts. It returns the minimum copper AWG gauge that keeps the round-trip drop within your budget, along with the required and actual conductor areas and the exact drop the recommended size will produce, so the answer is auditable rather than a bare chart lookup. The computation is fully deterministic — fixed arithmetic, no network, no randomness, no dates — and the same code runs free in your browser on this page. Use it while planning a run, then confirm ampacity and insulation rating separately before you buy cable.

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/phys/amp-to-wire-size

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/phys/amp-to-wire-size \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"current_a":20,"length":30}'

const res = await fetch("https://api.kit.forhosting.com/phys/amp-to-wire-size", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "current_a": 20,
    "length": 30
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/phys/amp-to-wire-size",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "current_a": 20,
    "length": 30
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/phys/amp-to-wire-size", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"current_a":20,"length":30}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"current_a":20,"length":30}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/phys/amp-to-wire-size", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "current_a": 20,
  "length": 30
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "phys.amp_to_wire_size",
  "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.

Limits

max_abs 1000000000000

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 →