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Time Zone Converter

Overview

Convert a date and time from one city's time zone to another's, with daylight saving time applied on that date. See the converted time and date, the time difference, both UTC offsets and whether DST is in effect.

Enter a time as it reads on the clock in one city and see what the clock says at that same moment in another. The converter looks up both cities' IANA time zones, works out each zone's UTC offset on the date you chose, including daylight saving time, and shows the converted time with its zone abbreviation, the full date at the destination, and whether that date is a day ahead or behind. It also lists both offsets, the difference between them and whether daylight saving time is in force in each city, which explains why the gap between London and New York is 5 hours most of the year but 4 for a few weeks in spring and autumn. Use it to schedule calls and meetings across continents or to check when a live event starts where you are.

Formula and example

UTC=Localfrom−Offsetfrom\displaystyle \text{UTC} = \text{Local}_{\text{from}} - \text{Offset}_{\text{from}}
Localto=UTC+Offsetto\displaystyle \text{Local}_{\text{to}} = \text{UTC} + \text{Offset}_{\text{to}}
Difference=Offsetto−Offsetfrom\displaystyle \text{Difference} = \text{Offset}_{\text{to}} - \text{Offset}_{\text{from}}

Where:

Local
— Wall-clock date and time: the one you enter in the from city, and the converted one in the to city.
Offset
— Each zone's UTC offset at that moment from the IANA time zone database, including daylight saving time. The from offset is checked again at the converted moment so times next to a clock change come out right.
UTC
— The same moment in Coordinated Universal Time, which never changes for daylight saving.
Difference
— How many hours the to city's clock is ahead of the from city's (negative when it is behind).

Worked example

A call at 09:00 in New York on 2 June 2025, converted to London. New York is on EDT (UTC−4) and London on BST (UTC+1) that day.

  1. Convert the New York time to UTC

    09:00−(−4:00)=13:00 UTC\displaystyle 09{:}00 - (-4{:}00) = 13{:}00\ \text{UTC}

  2. Convert UTC to London time

    13:00+1:00=14:00 BST\displaystyle 13{:}00 + 1{:}00 = 14{:}00\ \text{BST}

  3. Time difference

    (+1)−(−4)=+5 h\displaystyle (+1) - (-4) = +5\ \text{h}

Result

09:00 in New York is 14:00 the same day in London; London is 5 hours ahead, and daylight saving time is in effect in both cities.

FAQs

What time is 9:00 AM in New York in London?

Most of the year it is 2:00 PM in London, because London is 5 hours ahead of New York: on 2 June 2025, 09:00 EDT (UTC−4) is 14:00 BST (UTC+1). In the weeks when the United States has changed its clocks and the United Kingdom has not, the gap is 4 hours: on 14 March 2025, 09:00 EDT is 13:00 GMT.

Why is the time difference sometimes off by an hour?

Countries switch to and from daylight saving time on different dates. The United States moves its clocks forward on the second Sunday in March and back on the first Sunday in November; the European Union and the United Kingdom change on the last Sundays of March and October. In between, the usual gap shrinks by an hour. Southern-hemisphere countries such as Australia change in the opposite season, and many countries, including Japan, India and China, do not change at all.

How does the converter handle time zones with half or quarter hours?

It uses the exact offset of each zone. India is UTC+5:30 all year, so 09:00 in London on 15 January 2025 is 14:30 in Delhi, a difference of 5h 30m. Nepal (UTC+5:45) and parts of Australia (UTC+9:30) work the same way.

Why does the result say next day or previous day?

The converted moment can fall on another calendar date. 18:00 on 2 June 2025 in New York is 07:00 on Tuesday 3 June in Tokyo, 13 hours ahead. In the other direction, 08:00 on 15 January 2025 in Sydney is 13:00 on 14 January in Los Angeles, 19 hours behind.

What happens if I enter a time that is skipped when clocks go forward?

On the night clocks spring forward, one hour does not exist on the local clock. In New York on 10 March 2024 the clock jumped from 01:59 to 03:00, so 02:30 never happened. The converter reads such a time as one hour later, 03:30 EDT, and says so in a note. When clocks go back and an hour repeats, it uses the first occurrence.

What do UTC offset and daylight saving status mean?

The UTC offset is how far a zone's clock is ahead of or behind Coordinated Universal Time on that date, such as UTC−4 for New York in summer. Daylight saving status says whether the city observes DST at all and, if it does, whether the summer offset is in force on the date you entered.

How to use

Pick two cities, then a date and time in the first city, to see the same moment in the second city.

  1. Choose the from cityPick the city whose clock time you know, for example where a meeting is organised. New York is filled in by default.
  2. Choose the to cityPick the city you want the time for. London is the default.
  3. Set the date and timeEnter the date and time as they read in the from city. The date matters because daylight saving time changes offsets on different days in different countries.
  4. Read the converted timeThe top card shows the time and date in the to city and the time difference. The table shows whether it is the next or previous day there, both UTC offsets and whether daylight saving time is in effect.

Assumptions

  • Offsets and daylight saving rules come from the IANA time zone database built into your browser or device, so they follow its version.
  • Each city uses a single time zone; a few cities near zone borders have suburbs on a different clock.
  • A time skipped by a spring-forward change is read one hour later, and a repeated autumn hour is read as its first occurrence.
  • Zone abbreviations come from your browser's locale data; where no common abbreviation exists, a GMT offset such as GMT+9 is shown instead.

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