World clock. Every zone, ticking live.

How to use the World Clock

This world clock shows the current time in every city you add, side by side, updating once a second. Each card also shows the date there, the offset from UTC, whether that city is ahead of or behind your calendar day, and a sun or moon marker. It is for anyone who works with people, clients or family in other time zones.

Step by step

1. 1
   Start from the default cities

   On your first visit the clock shows your own time zone, marked You, plus New York, London and Tokyo. Your browser supplies your own zone, so there is nothing to set.

2. 2
   Add a city

   Open Add a city / time zone, pick a city, then press Add. Zones are listed by city and region, such as Kolkata, Asia. With the menu focused you can type the first letters of a city to jump to it. Adding a city that is already on screen just shows a message.

3. 3
   Choose how time is shown

   Press 12-hour or 24-hour. 12-hour is the default. Untick Show seconds if you only need hours and minutes.

4. 4
   Remove or reset

   Press the cross in the corner of a card to remove that city. Press Reset to defaults to go back to your zone, New York, London and Tokyo.

Reading a card

• The large figure is the current time in that city. Under the city name you see its region and its offset from UTC, for example UTC+5:30 for Kolkata or UTC-4 for New York in summer.
• The date line shows the weekday, month and day in that city, followed by a sun from 6 AM to 6 PM local time and a moon the rest of the time. Daytime cards also get a warm tint.
• The bottom line compares that city's calendar date with yours: +1 day ahead, 1 day behind or same day as you. Your own card reads your local time.
• Worked example: if you are in New York and it is 11 PM on a Monday, the Tokyo card shows about midday on Tuesday and reads +1 day ahead.

Tips and common mistakes

• Many zones are named after one big city. For San Francisco pick Los Angeles, and for Mumbai pick Kolkata.
• The sun and moon follow the clock, not real sunrise and sunset. They switch at 6 AM and 6 PM in every city.
• Cards stay in the order you added them. To change the order, remove cities and add them again in the order you want.
• If you leave the page open across a daylight saving change, the time updates on its own but the UTC offset under the name only refreshes when you reload or change the list.
• Your city list lives in this browser only. A different browser or device starts from the defaults.

Privacy and limits

All times are calculated by your browser from its own time zone data, and nothing is sent to a server. Your cities, the 12 or 24 hour choice and the seconds setting are saved in this browser's local storage under dh_wc_zones, dh_wc_fmt and dh_wc_sec. Clearing site data brings back the defaults.

Back to the tool

Every zone, one glance.

• Track live time for as many cities as you want, every card ticks once a second.
• Add any city or time zone: the picker lists every IANA zone your browser knows (usually 400+), with your local zone flagged “You”.
• Toggle 12-hour and 24-hour display and show or hide seconds to match your preference.
• See the day offset, ahead, behind or same day, computed from each zone's real calendar date, plus its exact UTC offset (half-hour zones included).
• Spot day vs. night at a glance with the sun / moon marker and a subtle card tint.
• Keep your list between visits, cities and preferences are saved in this browser only, no account needed.

Frequently asked questions.

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