Time Zone Converter

How to use the time zone converter

1. Set the source moment. Pick a date and a time, or press “Now” to jump to the current moment. The source zone starts as your own and can be changed to any city on your list.
2. Read the table. Every selected zone shows its local time, the date there, its UTC offset, how far ahead or behind the source it is, and a working-hours band.
3. Add the cities you need. Search by city, country or IANA identifier — “Tokyo”, “India” and “Europe/Berlin” all find the same kind of thing. Remove a city with the ✕ button.
4. Scan the meeting planner. Each row is one city and each cell one hour of the next 24, coloured by how civilised that hour is locally. Look for a column that is green all the way down.
5. Switch to a 12-hour clock if you prefer, and copy the whole table with one button.

How offsets are calculated

A time zone is not a fixed number of hours. It is a set of rules — a standard offset, plus daylight saving transitions with their own dates — maintained in the IANA time zone database and shipped with every browser and operating system.

This tool asks the browser directly. For a given instant it formats that instant in the target zone with Intl.DateTimeFormat and reads the timeZoneName part in longOffset style, which comes back as a string such as GMT-05:00. Parsing that gives the offset in minutes for that exact moment, which is what makes daylight saving fall out automatically.

Going the other way — from a wall clock to an instant — takes two passes, because the offset you need depends on the answer you are looking for. The tool guesses with one offset, recomputes the offset at the resulting instant, and applies it again. That converges everywhere except inside a transition, where by definition there is no single right answer.

Worked examples

A simple conversion. 09:00 UTC on 21 September 2026 is 18:00 in Tokyo the same day, at UTC+09:00, and 05:00 in New York, also the same day. Tokyo is 9 hours ahead of the source, New York 4 behind.

A day boundary. 02:00 UTC on 21 September 2026 is 19:00 on 20 September in Los Angeles — a -1 day marker in the table. Compared with Tokyo, which is at 11:00 on the 21st, Los Angeles is 16 hours behind and a calendar day back.

Spring forward in New York. Daylight saving begins at 02:00 local on 8 March 2026. At 06:59 UTC New York is still on UTC-05:00; one minute later, at 07:00 UTC, it is on UTC-04:00. A recurring 09:00 New York call moves by an hour relative to London that week, because the UK changes on a different date.

Autumn in Berlin. Central European Summer Time ends at 03:00 local on 25 October 2026. At 00:59 UTC Berlin reads UTC+02:00; at 01:00 UTC it reads UTC+01:00. The local hour from 02:00 to 03:00 happens twice that morning.

Half-hour and quarter-hour zones. India is at UTC+05:30 all year and Nepal at UTC+05:45. Offsets are not all whole hours, which is why the table shows minutes.

Tips for scheduling across zones

• Agree on a zone, not a time. “14:00 UTC” survives a forwarded invitation; “2 pm” does not.
• Watch the transition weeks. The US, Europe and Australia change clocks on different dates, so the gap between New York and London is five hours for most of the year but four for two weeks in March.
• The southern hemisphere is the other way round. Sydney is on summer time in January and standard time in July, so the gap to Europe widens and narrows twice a year.
• Not everywhere changes. Japan, India, most of Africa and Asia, Arizona and Queensland have no daylight saving at all.
• Check the day, not just the hour. A 09:00 Monday call in London is 18:00 Monday in Tokyo but 17:00 Sunday in Honolulu — a different working week entirely.
• Use the amber band sparingly. Somebody taking a 07:30 or 21:00 call is doing you a favour; rotating who does it is fairer than always picking the same zone.

Glossary

• IANA time zone – an identifier like Europe/Berlin that carries a region’s full history of offsets and daylight saving rules.
• UTC offset – how far local clocks are from Coordinated Universal Time at a given moment, written UTC+05:30.
• DST – daylight saving time, a seasonal shift of local clocks, usually by one hour.
• Instant – a single point on the timeline, independent of any zone.

Privacy

Everything is calculated in your browser using the time zone data your operating system already ships. No dates, times or city lists are sent anywhere; your selected zones are stored only in this browser’s local storage, and the reset button clears them back to the defaults.

Last reviewed: September 21, 2026