Time Zone Calculator
Convert a date and time from one zone to multiple destinations worldwide. Great for scheduling meetings across countries.
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How to Use the Time Zone Calculator
Select your source time zone and enter a date and time. Then select one or more destination time zones to see the converted time. Use the quick-select buttons to add popular time zones.
About This Tool
Convert any date and time between time zones worldwide. Select a source zone, enter your time, and see it converted to multiple destinations at once. Uses the IANA time zone database via the browser’s Intl API for accurate conversions including daylight saving time.
Typical scenarios: scheduling a kickoff call across a US-EU-APAC team where everyone needs to know local time without doing the math themselves; confirming a flight arrival time that spans a DST transition (September 2 in New York, September 3 in Auckland — when exactly does the plane land local?); coordinating a gaming tournament across multiple regions where the Twitch stream needs a single UTC reference but players want their local time on the schedule. Each of these breaks down when done manually because of DST shifts that happen on different dates in different hemispheres and because some zones (Nepal +5:45, India +5:30, Newfoundland -2:30) use non-integer UTC offsets.
Under the hood, conversions use Intl.DateTimeFormat with the timeZone option, which delegates to the browser's bundled IANA time-zone database (the tzdata file, which Chrome, Firefox, and Safari each update on their own release cycle). That gives correct historical DST rules too — the US moved from "last Sunday of April" to "second Sunday of March" in 2007, and a conversion for a 2005 date correctly uses the old rule. Abolished zones like "Europe/Simferopol" pre-2014 or "America/Metlakatla" still resolve if the browser's tzdata includes them.
Known limitation: your browser's tzdata is only as fresh as your last browser update — if a country changes its DST rules, it may take a browser release cycle (weeks) before the change propagates. For extremely recent rule changes (e.g., Brazil ending DST in 2019, Russia's 2014 offset shifts), check your browser version if results look off. Compared to a calendar app's time-zone picker, this tool shows multiple destinations side-by-side and doesn't require you to create an event first. See the Date Calculator for date arithmetic.
Quick Reference Table
| Time Zone | UTC Offset (Standard) |
|---|---|
| US Eastern (ET) | UTC−5 |
| US Central (CT) | UTC−6 |
| US Mountain (MT) | UTC−7 |
| US Pacific (PT) | UTC−8 |
| London (GMT/BST) | UTC+0 |
| Central Europe (CET) | UTC+1 |
| India (IST) | UTC+5:30 |
| Japan (JST) | UTC+9 |
| Sydney (AEST) | UTC+10 |
Frequently Asked Questions
Does this account for daylight saving time?
Yes. The calculator uses the Intl API which automatically applies DST rules for each time zone based on the date you enter.
How many time zones can I convert to at once?
You can select as many destination time zones as you want. Each shows the converted time simultaneously.
Is this accurate for historical dates?
The calculator is most accurate for modern dates. Historical time zone data may vary, especially for dates before standardized time zones were adopted.
Is my timezone selection or converted time saved after I close the page?
No. The Time Zone Calculator uses your browser’s Intl API and the IANA time zone database to convert between any two zones in real time. Your selected source/destination zones and the converted result are not saved — they reset on every page load. No server request is made during conversion.
Why are some time zones offset by 30 or 45 minutes?
Not all time zones are whole-hour offsets from UTC. India uses UTC+5:30, Nepal uses UTC+5:45, and the Chatham Islands use UTC+12:45. These unusual offsets reflect historical, political, and geographic decisions made by each country or territory.
Created by The Toobits Team · Engineering & Editorial
Toobits is built, tested, and maintained by a small independent engineering team. Every tool is written in TypeScript, runs entirely in the browser, and is reviewed against its source formulas before publication.
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