Skip to content
Calcenta

Time Zone Converter

Convert a time across cities and plan meetings that land in working hours everywhere - with daylight saving handled automatically.

Time Zone Converter

New York

9:00 AM

Wednesday, September 2, 2026 · EDT · UTC-4

Meeting planner

Green is working hours, amber is early or late, red is the middle of the night.

  • 2:00 PMWed Sep 2
    +5 hoursGMT+1 · UTC+1
  • 3:00 PMWed Sep 2
    +6 hoursGMT+2 · UTC+2
  • 6:30 PMWed Sep 2
    +9:30 hoursGMT+5:30 · UTC+5:30
  • 10:00 PMWed Sep 2
    +13 hoursGMT+9 · UTC+9

How the time zone converter calculation works

Converting a time between two places is arithmetic on UTC offsets. Every zone is defined as an offset from Coordinated Universal Time, so the conversion is:

Target time = source time − source offset + target offset

New York in January is UTC−5 and London is UTC+0, so 9:00 AM in New York is 9 − (−5) + 0 = 2:00 PM in London.

What makes this genuinely difficult is that offsets are not constant. They change with daylight saving time, and they do not change on the same date everywhere.

  • The US switches on the second Sunday in March and the first Sunday in November.
  • The EU and UK switch on the last Sunday in March and the last Sunday in October.

For roughly three weeks in March, the usual five-hour gap between New York and London becomes four. Meetings booked as a fixed "2pm London / 9am New York" silently shift by an hour for one of the parties. This tool reads the IANA time zone database through your browser, so those transitions are applied automatically for the specific date you pick rather than assumed from a fixed offset.

Not every offset is a whole hour. India is UTC+5:30, Nepal UTC+5:45, and parts of Australia UTC+9:30. Roughly a quarter of the world's population lives in a zone offset by something other than a whole number of hours.

The date can differ too. When it is 9:00 AM Monday in Los Angeles it is already 2:00 AM Tuesday in Tokyo. The meeting planner above flags a next-day or previous-day result explicitly, because a correct time on the wrong day is the most common scheduling mistake there is.

Two habits that prevent most cross-zone confusion:

  • Write times with the zone attached. "15:00 UTC" or "3pm ET" is unambiguous; "3pm" is not. Adding UTC in brackets removes all doubt for a global audience.
  • Let the calendar do the conversion. Create the event in your own zone and let each attendee's calendar render it in theirs. Manually converting and typing a local time into an invitation is where errors get introduced.

The planner below colors each city by local hour, so you can see at a glance whether a slot lands in the working day, the early morning, or the middle of the night.

Frequently asked questions

How do I convert a time between two time zones?

Subtract the source zone offset from the time and add the target zone offset. New York at UTC-5 and London at UTC+0 differ by five hours, so 9:00 AM in New York is 2:00 PM in London - but only when both are on standard time.

Why does the time difference between two cities change?

Daylight saving time starts and ends on different dates in different regions. The US springs forward on the second Sunday in March while the EU and UK wait until the last Sunday, so for about three weeks the usual gap between New York and London is four hours instead of five.

Which countries have half-hour time zones?

India is UTC+5:30, Iran UTC+3:30, Afghanistan UTC+4:30, and parts of Australia UTC+9:30. Nepal uses UTC+5:45, one of only a handful of 45-minute offsets. Roughly a quarter of the world lives in a zone that is not offset by a whole hour.

What is UTC and how does it differ from GMT?

UTC is the modern atomic time standard all zones are defined against. GMT is a time zone based on the Greenwich meridian. They are within a second of each other in practice, and the UK uses GMT in winter and British Summer Time in summer, so GMT is not always the UK's current time.

How do I schedule a meeting across many time zones?

Look for a window that falls in working hours for the largest number of participants, and rotate awkward slots between regions rather than always inconveniencing the same group. The planner above colors each city by local hour so you can find that overlap quickly.

Does this account for daylight saving automatically?

Yes. The converter uses your browser's copy of the IANA time zone database, which contains the actual transition rules for every zone. Changing the date changes the offsets applied, so a meeting planned across a DST boundary shows the correct local times.

Related everyday calculators