ForHosting KIT · Travel & geography

Polaris latitude calculator

An observed Polaris altitude of 40° with corrections of 0.5, -0.1 and 0.05 gives a latitude of 40.45°. You bring the reading and the corrections; the calculator adds them in one step and rounds only at the end. Free in your browser.

Free
Runs in your browser
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Run — free How it works & API

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Worked example

If you enter

Ho deg: 40
A0: 0.5
A1: -0.1
A2: 0.05
Decimal places: 4

You get

Lat deg: 40.45

Latitude ≈ Ho + a0 + a1 + a2 with corrections as inputs (no almanac network). Search intent: polaris latitude calculator. No network calls or random seeds are required. Failed

From the altitude of Polaris to your latitude

The method starts from one measurement: the observed altitude of Polaris above the horizon, written Ho and expressed in degrees. That altitude is already close to your latitude, and three small corrections, a0, a1 and a2, bring it closer. The calculator simply adds them: latitude is approximately Ho plus a0 plus a1 plus a2. With an altitude of 40° and corrections of 0.5, -0.1 and 0.05, the latitude comes out at 40.45°. Nothing is fetched from an almanac or a network, so the same reading always gives the same latitude, which makes it useful for practice, teaching and checking a calculation done by hand.

Common mistakes when working out latitude from Polaris

The most frequent slip is losing a minus sign: a negative correction must lower the result, as -0.1 does in the example. The second is mixing units, entering a correction in minutes of arc while the altitude is in degrees; every value here must be in degrees. A third is rounding each correction before adding them, which can shift the last decimal; the calculator rounds once, at the end, and only if you choose a number of decimals. Finally, remember the result is an approximation built on the corrections you supply, so its quality depends on taking them from the right table.

What you can do with it

Teaching

Pinned goldens.

FAQ

Where do the a0, a1 and a2 corrections come from?

You supply them from your own tables. The calculator does not consult an almanac or anything online: it takes the three corrections exactly as you enter them and adds them to the observed altitude.

In what unit should I enter the corrections?

In degrees, the same unit as the observed altitude. If your table gives minutes of arc, divide by 60 before entering them, otherwise a small correction will be counted as a large one.

Can a Polaris correction be negative?

Yes. Enter it with its minus sign and it is subtracted. In the example above, the a1 correction of -0.1 lowers the result, which is why the latitude ends at 40.45 rather than higher.

How is the latitude rounded?

Only when you ask for a number of decimals, and only once, on the final sum, using half-up rounding. The corrections are never rounded one by one, so the last decimal does not drift.

Related tools

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/geo/polaris-latitude

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/geo/polaris-latitude \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"ho_deg":40}'

const res = await fetch("https://api.kit.forhosting.com/geo/polaris-latitude", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "ho_deg": 40
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/geo/polaris-latitude",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "ho_deg": 40
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/geo/polaris-latitude", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"ho_deg":40}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"ho_deg":40}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/geo/polaris-latitude", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "ho_deg": 40
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "geo.polaris_latitude",
  "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.

Technical notes

The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets, CMS hooks, automation, or teaching demos.

How it works

Latitude ≈ Ho + a0 + a1 + a2 with corrections as inputs (no almanac network). lat = Ho + a0 + a1 + a2. No network calls or random seeds are required. Failed jobs are not billed. No network calls or random seeds are required. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets, CMS hooks, automation, or teaching demos. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets,

Inputs, limits and rounding

Optional decimals use half-up once. Optional output fields are omitted, never null. No network calls or random seeds are required. Failed jobs are not billed. No network calls or random seeds are required. Provide required JSON fields with DOM-safe names. Invalid types raise invalid_input. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets, CMS hooks, automation, or teaching demos. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets, CMS hooks,

When to use it

Use when search intent matches. Latitude ≈ Ho + a0 + a1 + a2 with corrections as inputs (no almanac network). EN-only delivery; Nitro hydrates locales. No network calls or random seeds are required. Failed jobs are not billed. No network calls or random seeds are required. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from spreadsheets, CMS hooks, automation, or teaching demos. The calculator is free in the browser, deterministic, and identical on the API path. Inputs are validated before arithmetic so invalid payloads fail with invalid_input. Half-up rounding is applied once from raw IEEE values when decimals are requested. Use the same JSON from

Integration use cases

Quick check

Free widget.

Automation

API same JSON.

Technical questions

Free?

Yes tier A.

Network?

No.

Bad input?

invalid_input.

API?

Yes.

Locales?

EN-only; Nitro hydrates.

Read the full KIT documentation →

Run — free