How to use it
- Set the date and time, and choose which city that time belongs to. Now fills in the current time.
- Every city card shows the same moment in local time, with the date, the UTC offset and whether daylight saving is in effect there.
- Add cities by name — in English or Chinese — or by IANA time zone name, such as Asia/Kolkata. Remove a card with ✕. Your list is remembered in this browser.
- Use the meeting planner grid to find a slot. Hours inside each city's working day are shaded; hours that suit everyone are shaded darker. Tap an hour to move all the cards to it.
How time zones are calculated
A time zone is not just an offset from UTC. It is a set of rules that say which offset applies at each moment in history: when daylight saving starts and ends, and every change a government has made. Those rules are collected in the IANA time zone database, maintained by volunteers and updated several times a year. Operating systems and browsers ship a copy of it, and this page uses your browser's copy through the standard Intl API. Nothing is hard-coded, so when a country changes its rules, the result is correct as soon as your browser updates.
The hour that is skipped and the hour that repeats
When daylight saving begins, local clocks jump forward: in New York on 8 March 2026 the time goes from 01:59 straight to 03:00, so 02:30 does not exist. When it ends, clocks go back: on 1 November 2026 the hour from 01:00 to 01:59 happens twice, once on daylight time and once on standard time. A converter that ignores this silently gives you a time an hour off. This page detects both cases and says so. For a skipped time it moves forward by the length of the gap — 02:30 becomes 03:30 — which is the same rule the new JavaScript Temporal API and most calendar software use. For a repeated time it picks the first occurrence.
The dates differ by region. The US and Canada change on the second Sunday of March and the first Sunday of November; the EU and UK on the last Sunday of March and October, at 01:00 UTC. For two or three weeks each spring and autumn the gap between New York and London is therefore four hours instead of the usual five — the most common reason a regular transatlantic call suddenly starts at the wrong time. China, Japan, India and most of Asia, Africa and South America do not use daylight saving at all, and in the southern hemisphere it runs roughly from October to April.
Offsets that are not whole hours
India is UTC+5:30, Nepal UTC+5:45, and parts of Australia are on half-hour offsets. The cards show minutes whenever they are not zero, and the planner grid lists the real local minute rather than rounding to the hour.
Examples
| Input | Result |
|---|---|
| 9:00 on 7 March 2026 in New York | 14:00 UTC (New York is UTC−5, standard time) |
| 9:00 on 8 March 2026 in New York | 13:00 UTC (daylight saving has started: UTC−4) |
| 2:30 on 8 March 2026 in New York | does not exist; shown as 3:30 EDT (07:30 UTC) |
| 1:30 on 1 November 2026 in New York | happens twice; the first is 05:30 UTC |
| 1:30 on 29 March 2026 in London | does not exist; UK clocks jump from 01:00 to 02:00 |
| 17:00 on 5 October 2026 in Los Angeles | 9:00 the next day in Tokyo |
Finding a meeting slot. On Monday 5 October 2026, London (UTC+1) and New York (UTC−4) share four working hours: 14:00 to 18:00 in London, which is 9:00 to 13:00 in New York. Add Shanghai (UTC+8) and there is no hour inside everyone's 9-to-6 working day — someone will have to take an early or late call, and the grid shows exactly how early or late for each option.
Other offsets worth knowing: Mumbai and New Delhi are UTC+5:30, Kathmandu UTC+5:45, and Sydney is UTC+11 in January because it is on summer time then.
Limits
- Future rule changes. Governments sometimes change daylight-saving rules at short notice. Results for dates after such a change are only correct once your browser has an updated time zone database.
- Working hours are fixed at 9:00–18:00, Monday to Friday. Weekends differ in some countries — Friday and Saturday in several Middle Eastern countries — and public holidays are not considered.
- The planner rows follow the reference city's clock. On the day that city changes its clocks, one row is skipped or repeated.
- Historical dates are converted with the rules of the time, as far as the IANA database records them, but very old dates may use local mean time rather than a standard offset.
Frequently asked questions
Does this account for daylight saving time?
Yes. It uses your browser's copy of the IANA time zone database, which contains every region's daylight-saving rules, and it warns you when a time is skipped or repeated by a clock change.
What is the time difference between London and New York?
Usually five hours. For a few weeks in March and in late October to early November it is four, because the US and UK change their clocks on different dates.
Why is India on a half-hour offset?
India Standard Time is UTC+5:30, chosen in the 1940s as a compromise across the country's width. Nepal is UTC+5:45. The converter shows these offsets exactly.
Is my list of cities saved?
Yes, in your browser's local storage under the key tz-cities, so it is there next time. It is never sent anywhere; clearing site data removes it.
Can I type a city that is not in the suggestions?
Type its IANA time zone name, such as America/Denver or Asia/Almaty. Every zone your browser supports is accepted.