This guide covers World Clock Guide | TimeFlow — what it means, how it works, and how to use it. The explanations below are followed by worked examples with real dates and real times, a set of frequently asked questions, and links to the tools that do the calculation for you: the time zone converter, the world clock, and the UTC converter. Where a number is given — an offset, a date, a count — it is computed from the IANA Time Zone Database for the date stated, not copied from a table that may be out of date.

Try the tool: Time Zone Converter — convert any time between any two cities, with the daylight saving rules for the date you choose.

A world clock shows the current time in cities around the world, side by side. It is the fastest way to answer the question 'what time is it there?' — and, just as importantly, 'what day is it there?'

The world clock on this site covers 100 cities, with each city's current local time, date, UTC offset and daylight saving status. The time is computed from the IANA Time Zone Database in your browser, so it is always current — it is not a table that goes out of date.

The best way to use a world clock is to learn the offsets of the cities you deal with. There are only a few numbers to remember: New York is UTC−05:00 in winter, London is UTC+0, Paris is UTC+01:00, Dubai is UTC+04:00, Mumbai is UTC+05:30, Singapore is UTC+08:00, Tokyo is UTC+09:00, Sydney is UTC+10:00 in winter. With those, you can convert any time in your head.

A world clock also teaches you the shape of the world. The largest time differences are between the Pacific and the Atlantic: Sydney and Los Angeles are 17–19 hours apart, so when it is Monday morning in Sydney it is still Sunday in Los Angeles. And the date line means that the first places to see each new day are the islands of Kiribati, in the middle of the Pacific.

In practice

A world clock shows the current time in several cities at once, and the first step is to choose the cities that matter to you. The world clock shows every major city, with the time, the date and the offset, and you can add the cities you call most often. The habit that makes it useful is to check it before you send a message or schedule a call — ten seconds that saves a 3am phone call.

The second step is to learn to read it. A world clock shows the time, the date and the offset for each city — and the date matters as much as the time, because a city 12 hours ahead is living in tomorrow. The world clock for Tokyo shows the time, the offset, the daylight saving dates and the best time to call, all on one page.

The third step is to use it for planning. The world clock tells you what time it is now; the meeting planner tells you when to meet, by showing the overlap of working hours; and the time zone converter converts any proposed time into every city. The three tools together cover every question a world clock can answer.

The numbers: what 12:00 UTC looks like around the world

The table below shows the local time in eight major cities when it is 12:00 UTC on 15 January 2026. The spread is the whole point of time zones: the same moment is a morning in New York, midday in London, evening in Mumbai and night in Tokyo.

City Local time when it is 12:00 UTC (15 January 2026) UTC offset
New York 7:00 am UTC−05:00
London 12:00 pm UTC+00:00
Paris 1:00 pm UTC+01:00
Dubai 4:00 pm UTC+04:00
Mumbai 5:30 pm UTC+05:30
Tokyo 9:00 pm UTC+09:00
Sydney 11:00 pm UTC+11:00
Los Angeles 4:00 am UTC−08:00

Two things stand out. First, the range: from 04:00 in Los Angeles to 23:00 in Sydney, the same instant covers almost the whole day. Second, the half hour: Mumbai is at 17:30, not 17:00 or 18:00, because India uses a half-hour offset (UTC+05:30). If you convert a time for Mumbai by rounding to the nearest hour, you will be half an hour out. The UTC converter shows the offset and the local time for any city on any date, and the time zone converter converts between any two cities directly.

The offsets change during the year for the cities that observe daylight saving. The same eight cities in January and in July:

City Offset in January 2026 Offset in July 2026 Changes?
New York UTC−05:00 UTC−04:00 Yes — one hour
London UTC+00:00 UTC+01:00 Yes — one hour
Paris UTC+01:00 UTC+02:00 Yes — one hour
Dubai UTC+04:00 UTC+04:00 No
Mumbai UTC+05:30 UTC+05:30 No
Tokyo UTC+09:00 UTC+09:00 No
Sydney UTC+11:00 UTC+10:00 Yes — one hour
Los Angeles UTC−08:00 UTC−07:00 Yes — one hour

New York, London, Paris, Sydney and Los Angeles all change by one hour between January and July; Dubai, Mumbai and Tokyo do not, because they do not observe daylight saving. That is why a conversion done in January can be wrong in July — and why the UTC converter asks for the date.

Key facts

  • UTC never observes daylight saving. It is the fixed reference that every other time zone is measured against.
  • The world uses 38 different UTC offsets, from UTC−12:00 to UTC+14:00 — a span of 26 hours.
  • Nepal is on UTC+05:45, the only 45-minute offset in regular use. India is on UTC+05:30.
  • The Prime Meridian is at 0 degrees longitude, through Greenwich, London.
  • A time written in UTC means the same thing everywhere on Earth, in January and in July.

Frequently asked questions

What is a world clock?

A tool that shows the current time in several cities at once, with the date and the UTC offset for each city.

How do I read a world clock?

Each city shows its time, its date and its offset from UTC. The date matters as much as the time, because a city 12 hours ahead is living in tomorrow.

Which cities should I put on my world clock?

The ones you call, work with or travel to most often. The world clock shows every major city, and you can add the ones you need.

Does a world clock show daylight saving?

Yes. The offset shown for a city is the one in effect today, so it changes when the city moves its clocks — and the dates differ by country.

What is the difference between a world clock and a time zone converter?

A world clock shows what time it is now; a converter takes a specific time in one city and gives the time in another. Use the time zone converter for the second job.

What time is it in Tokyo when it is 12:00 UTC?

23:00 the same day — Tokyo is UTC+09:00 all year, so you add nine hours to 12:00 UTC. In New York it is 07:00 in winter (UTC−05:00) and 08:00 in summer (UTC−04:00). The UTC converter shows the time in any city for 12:00 UTC.

What is the time difference between London and Tokyo?

Nine hours in January 2026: London is UTC+00:00 and Tokyo is UTC+09:00. In July it is eight hours, because London moves to UTC+01:00 while Tokyo stays on UTC+09:00. The time zone converter gives the difference for any two cities and any date.

Related pages

Sources

  • IANA Time Zone Database, via Node.js Intl (Intl.DateTimeFormat with timeZone) — offsets, daylight saving dates and local times in this article were worked out from the IANA database, not typed from memory.
  • TimeFlow's own time-zone data (data/cities.ts, data/dst.ts), computed from the IANA database.
  • Time zone rules and offsets: the IANA Time Zone Database, as applied by this site's tools. Offsets and daylight saving dates on this page are computed from the database for the dates stated.
  • TimeFlow's time zone converter, world clock and UTC converter — the live tools behind the numbers on this page.
  • Time-zone and daylight saving rules are set by governments and can change. For flights, deadlines and meetings that cannot move, confirm the time with an official source.