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Time Zone Converter

Convert time between any time zones worldwide

Convert Time

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How Time Zone Conversion Works

Time zones are regions that observe the same standard time, typically expressed as an offset from UTC (Coordinated Universal Time).

UTC Offsets

Each time zone has a UTC offset. For example, IST is UTC+5:30 and EST is UTC-5:00. To convert, calculate the difference between the two offsets.

Daylight Saving Time

Many countries shift clocks forward by 1 hour during summer months. This tool automatically accounts for DST using the Intl API.

Converting time zones without getting it wrong

To convert a time, go through UTC: subtract the source city’s offset to get UTC, then add the destination’s. The two mistakes that cause almost every missed call are forgetting that daylight saving moves one side but not the other, and forgetting that the date can change even when the time looks reasonable.

Offsets you will actually use

ZoneAbbrev.UTC offsetObserves DST?
India Standard TimeIST+5:30No
Coordinated Universal TimeUTC+0:00No
Greenwich Mean Time / British Summer TimeGMT / BST+0 / +1Yes (UK)
Central European TimeCET / CEST+1 / +2Yes
Eastern Time (US)EST / EDT−5 / −4Yes
Central Time (US)CST / CDT−6 / −5Yes
Mountain Time (US)MST / MDT−7 / −6Yes, except Arizona
Pacific Time (US)PST / PDT−8 / −7Yes
Gulf Standard TimeGST+4No
Singapore TimeSGT+8No
China Standard TimeCST (China)+8No
Japan Standard TimeJST+9No
Australian Eastern TimeAEST / AEDT+10 / +11Yes, in NSW/VIC/ACT/TAS
New Zealand TimeNZST / NZDT+12 / +13Yes

The method, in three steps

  1. Write the source time with its offset: 3:00 pm IST is 15:00 +5:30.
  2. Convert to UTC by subtracting the offset: 15:00 − 5:30 = 09:30 UTC.
  3. Add the destination offset: for New York in July (EDT, −4) that is 09:30 − 4:00 = 05:30, i.e. 5:30 am the same day.

Worked example that crosses the date line

11:00 pm Monday in San Francisco → India

San Francisco in November is PST, UTC−8. 23:00 − (−8) = 07:00 UTC Tuesday.

07:00 UTC + 5:30 = 12:30 IST.

12:30 pm on Tuesday in India — a full calendar day later. This is the single most common scheduling error on India–US calls.

Abbreviations that mean two different things

Time zone abbreviations are not unique and should never be used in anything machine-read. CST is US Central Standard Time (UTC−6), China Standard Time (UTC+8) and Cuba Standard Time (UTC−5). IST is India Standard Time (+5:30), Irish Standard Time (+1) and Israel Standard Time (+2). BST is British Summer Time (+1) and Bangladesh Standard Time (+6). For calendars, code and contracts, use an IANA identifier such as Asia/Kolkata or America/New_York, which encode the full DST history.

Half-hour and 45-minute zones

More questions people ask

How do I convert IST to EST?

Subtract 10 hours 30 minutes from IST to get EST, or 9 hours 30 minutes to get EDT during US daylight saving. 6:00 pm IST is 7:30 am EST, or 8:30 am EDT.

Why do some time zones use 30 or 45 minutes?

A zone is a political choice, not a mathematical one. Countries pick an offset that puts noon somewhere near solar noon for the bulk of their population, and when a whole-hour offset would be badly wrong for a country that straddles a meridian, a half or quarter hour fits better. Nepal chose +5:45 partly to be distinct from India.

What is the largest time difference between two places?

26 hours, between UTC+14 (Line Islands, Kiribati) and UTC−12 (Baker and Howland Islands). That means there are moments when three different calendar dates exist on Earth at once.

Does UTC ever change for daylight saving?

No. UTC is a fixed reference and never shifts. Only local zones move relative to it, which is exactly why converting through UTC is reliable and converting city-to-city by memory is not.

What is the safest way to schedule a recurring international meeting?

Store it in the calendar as a zone-aware event using an IANA zone such as Asia/Kolkata rather than a fixed UTC time. That way the meeting stays at the right local hour for the organiser and every attendee’s calendar recalculates when their own region changes.

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Frequently Asked Questions

What is UTC?
UTC (Coordinated Universal Time) is the primary time standard. Time zones are expressed as offsets from UTC.
What is the time difference between IST and EST?
IST (UTC+5:30) is 10 hours and 30 minutes ahead of EST (UTC-5:00).
Does this tool handle daylight saving time?
Yes, it uses the browser's Intl.DateTimeFormat API which automatically handles DST transitions.
How many time zones are there in the world?
There are 38 time zones, ranging from UTC-12:00 to UTC+14:00.

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