ForHosting KIT · Developer Utilities

Time difference between cities calculator

A time difference between cities calculator answers the everyday travel and calling question: if it is a given local hour in one city, what time is it in the other, and how many hours sit between those two clocks?

● BetaFree · in your browser

Run — free How it works & API

Use it from WebAPIEmailTelegramApp soon

You name both cities and supply each city's fixed UTC offset in hours—minus five for New York on standard time, plus nine for Tokyo, plus twelve for Auckland, minus ten for Honolulu—plus the local hour and optional minute in the first city. The solver returns the signed hour difference, both local clocks as HH:MM, the calendar-day shift after midnight wrap, a shortest-path wrap into a plus-or-minus twelve hour window, and a flag that marks when the two offsets sit more than half a day apart, which is the civil-offset signature of a date-line crossing. Offsets outside plus or minus fourteen hours are rejected. The arithmetic is deterministic: no network, no host clock, no IANA zone database, and no daylight-saving guesswork, so the free browser runner and the API always agree.

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/travel/time-difference-cities

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/travel/time-difference-cities \
  -H "Authorization: Bearer $KIT_KEY" \
  -H "Content-Type: application/json" \
  -d '{"city_a":"New York","utc_a":-5,"city_b":"Tokyo","utc_b":9,"hour":15}'

const res = await fetch("https://api.kit.forhosting.com/travel/time-difference-cities", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.KIT_KEY}`,
    "Content-Type": "application/json"
  },
  body: JSON.stringify({
    "city_a": "New York",
    "utc_a": -5,
    "city_b": "Tokyo",
    "utc_b": 9,
    "hour": 15
  })
});
const { task_id } = await res.json();

import os, requests

res = requests.post(
    "https://api.kit.forhosting.com/travel/time-difference-cities",
    headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
    json={
    "city_a": "New York",
    "utc_a": -5,
    "city_b": "Tokyo",
    "utc_b": 9,
    "hour": 15
},
)
task_id = res.json()["task_id"]

<?php
$res = file_get_contents("https://api.kit.forhosting.com/travel/time-difference-cities", false, stream_context_create([
  "http" => [
    "method"  => "POST",
    "header"  => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
    "content" => '{"city_a":"New York","utc_a":-5,"city_b":"Tokyo","utc_b":9,"hour":15}',
  ],
]));
$task = json_decode($res, true);

body := bytes.NewBufferString(`{"city_a":"New York","utc_a":-5,"city_b":"Tokyo","utc_b":9,"hour":15}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/travel/time-difference-cities", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)

Example request

{
  "city_a": "New York",
  "utc_a": -5,
  "city_b": "Tokyo",
  "utc_b": 9,
  "hour": 15
}

Example response

{
  "task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
  "type": "travel.time_difference_cities",
  "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_offset_hours`	14
`max_city_len`	80

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 →