World Clock
See local time in several cities at once and find the working hours you share before booking a meeting.
How to use
- Six cities are shown by default: Shanghai, Tokyo, London, New York, Los Angeles and Sydney. Clocks tick every second.
- Pick another zone under Add a city and press Add. Remove a card with the button on it.
- For a meeting, set the date and your start time. Every city shows its local time and whether that hour counts as working time.
- The shared window lists start times where every selected city sits between 08:00 and 21:00, using your time zone.
- Your city list is stored in this browser. Another device starts from the default set.
FAQ
Does daylight saving time adjust automatically?
Why do some cities differ by 30 or 45 minutes?
How is the shared window calculated?
Where is my city list stored?
How to use
- Read the default six
The page opens with Shanghai, Tokyo, London, New York, Los Angeles and Sydney. Each card ticks every second and shows the UTC offset plus a today or tomorrow tag.
- Add or remove cities
Pick a zone under Add a city and press Add. Remove a card with the button on it. At least one city always stays.
- Set the meeting slot
The planner starts on today at 10:00 in your zone. Change the date or the start hour and the table below converts every city.
- Find the shared window
Each city shows its local time and status, and the bottom line lists start hours where every city sits between 08:00 and 21:00.
- Copy and send
Press Copy meeting times to get the date and every local time as plain text. Paste it into chat or email.
About this tool
A day is divided into 24 hours by the rotation of the earth, yet collaboration needs one shared name for the same instant. Time zones are that agreement. Beijing runs 8 hours ahead of London and New York runs 5 hours behind it. A three-way call therefore appears as three different numbers on three calendars. A world clock converts one instant into every city at once and removes the mental arithmetic from scheduling.
This page converts with the browser's built-in IANA time zone database rather than hard-coded offsets, so daylight saving and historical rules come from system data. Six cities are shown by default and every card refreshes each second with its UTC offset and a today or tomorrow tag. The planner tests each hour of the chosen date. It keeps the start times where all cities fall between 08:00 and 21:00, then merges consecutive hours into ranges. Your city list stays in this browser.
How it works
Time zones do not follow meridians exactly. China spans five geographic zones but keeps a single UTC+8, so sunrise in Xinjiang arrives two hours after Beijing. India uses UTC+5:30 nationwide, Nepal uses UTC+5:45 and central Australia uses UTC+9:30. Those half-hour and quarter-hour offsets make mental math unreliable and force software to read a full zone table instead of a fixed offset. Countries near the date line also skip or repeat a calendar day as a whole.
For cross-zone meetings the working day itself needs a definition. Most teams treat 09:00 to 18:00 local as the core. Engineering teams may accept 08:00 to 21:00, and support teams have to cover someone else's daytime. Squeezing everyone into one window often leaves an hour or two, which is why rotating the awkward slot beats fixing it for one person. The week of a daylight saving change is the riskiest. Europe and the United States switch on different dates, so the same invite can read an hour apart in two cities. Check both calendars before sending.
When to use it
- A three-city standup
A team sits in Shanghai, London and San Francisco and needs one weekly sync. Add all three and test hours from 08:00 to 22:00. Only your early morning overlaps the other side's evening, so the standup rotates between two slots and nobody owns the night shift forever.
- Remote interviews
The candidate lives in Berlin and the interviewer in Tokyo. Filter for the candidate's morning first, then confirm Tokyo is not deep in the night. Copy the result into the invite so the candidate sees their own local time without another round of messages.
- Support coverage
A product going global needs support through the US and European day, scheduled from Beijing. Add New York, London and Los Angeles to see how the three working days overlap, then work backward to how many agents each shift needs.
Tips & tricks
- Pin the three cities you work with most and add others on demand. A short list is easier to scan at a glance.
- Before sending an invite, check both calendars during a daylight saving change week. One hour of drift is common.
- When the shared window is only an hour or two, rotate the awkward slot instead of parking it on one person every week.
Things to watch
- Trusting one clock
A 15:00 slot on your calendar may already be midnight for the other side. Add the other city before sending the invite and check both the hour and the weekday. Cross-date cases are the easiest to misread, and a wrong weekday can push the meeting a full day out.
- Forgetting the DST switch
Europe and the United States change clocks twice a year on different dates. During that week the same invite can show an hour apart in two cities. Confirm on both calendars, or write the meeting in UTC so nobody has to guess which side is right.
- Treating the window as a rule
The shared window is a filter, not a policy. Some people will happily start an hour early and others prefer a late call. Ask for preferences before locking a slot that looks clean in the table, and revisit the schedule when the team changes.