This guide covers What Is a UTC Offset? | 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a count — it is computed from the IANA Time Zone Database for the date stated, not copied from a table that may be out of date.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 UTC offset is the difference between a place's local time and UTC (Coordinated Universal Time). It is written as UTC plus or minus hours and minutes: New York is UTC−05:00 in winter, London is UTC+0 in winter, Tokyo is UTC+09:00, Mumbai is UTC+05:30, Kathmandu is UTC+05:45.

The offset tells you everything you need for a conversion. To get the local time from UTC, add the offset: 12:00 UTC is 07:00 in New York in winter (12:00 minus 5 hours), 12:00 in London, 17:30 in Mumbai, 21:00 in Tokyo. To go the other way, subtract it. That is the whole calculation — no tables, no lookup, just one addition.

Most offsets are whole hours, but not all. India, Sri Lanka, Iran and parts of Australia use half-hour offsets (UTC+05:30, UTC+03:30, UTC+09:30), and Nepal uses UTC+05:45 — the world's only 45-minute offset in regular use. These exist because the countries sit between the neat 15-degree slices, and they chose an offset that puts noon closest to the middle of the day.

An offset can change during the year. Any place that observes daylight saving has two offsets: a standard offset in winter and a daylight offset in summer, one hour ahead. New York is UTC−05:00 in winter and UTC−04:00 in summer; London is UTC+0 in winter and UTC+01:00 in summer. Places that do not observe daylight saving — Tokyo, Dubai, Singapore, Mumbai — have one offset all year, which is why their times are the easiest to remember.

In practice

The offset is the only number you need to convert a time. It is written with a sign and hours and minutes: UTC−05:00 for New York in winter, UTC+01:00 for Paris in winter, UTC+05:30 for Mumbai, UTC+05:45 for Kathmandu. Add the offset to UTC to get local time; subtract it to go back. A negative offset means the place is behind UTC, a positive one means it is ahead.

Offsets are not always whole hours, and the exceptions are the ones people get wrong. India is UTC+05:30, Iran is UTC+03:30, parts of Australia are UTC+09:30 and UTC+10:30, and Nepal is UTC+05:45 — the only 45-minute offset in regular use. If you convert a time for Mumbai or Kathmandu by rounding to the nearest hour, you will be half an hour out, and the meeting will start without you.

An offset can also change during the year. Any place that observes daylight saving has two offsets: New York is UTC−05:00 in winter and UTC−04:00 in summer, London is UTC+0 in winter and UTC+01:00 in summer. That is why you should always check the offset for the date you care about, not the offset you remember — the UTC converter shows the offset for any city on any date, and the time zone converter converts between any two cities directly.

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 UTC offset?

The difference between a place's local time and UTC. New York is UTC−05:00 in winter, London is UTC+0, Tokyo is UTC+09:00, Mumbai is UTC+05:30.

How do I convert from UTC?

Add the offset to the UTC time. 12:00 UTC is 07:00 in New York in winter, 12:00 in London, 17:30 in Mumbai and 21:00 in Tokyo.

Are all offsets whole hours?

No. India is UTC+05:30, Iran is UTC+03:30, parts of Australia are UTC+09:30 and UTC+10:30, and Nepal is UTC+05:45 — the only 45-minute offset in regular use.

Can an offset change during the year?

Yes. Any place that observes daylight saving has two offsets: New York is UTC−05:00 in winter and UTC−04:00 in summer.

What is a negative offset?

It means the place is behind UTC. New York at UTC−05:00 is five hours behind UTC, so when it is 12:00 UTC it is 07:00 in New York.

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.