World Clock

Reading the clocks

The top row is your own time, taken from your device's clock and time zone. Below it is every other place on your list, ordered from west to east, so the list reads like a map of the day moving round the world. Each row shows the local time ticking to the second, the date there, and how far ahead or behind your own clock it is. When a place has already reached tomorrow, or is still on yesterday, the date says so in words, which is the detail that trips people up when they message a colleague on the other side of the world.

Each row also says what part of the day it is there: night, early morning, morning, afternoon, evening or late evening. That is the "it's 3 a.m. there" check at a glance. At 03:04 UTC on 21 June, for example, it is 12:04 PM on Sunday in Tokyo, 4:04 AM in London with the sky just starting to lighten, and 11:04 PM on Saturday in New York — three very different answers to "is now a good time to call?".

Day, twilight and night from the real sun

The shading on each row is not a guess from the hour. For a city, the page works out where the sun is in that city's sky at this moment, from its latitude and longitude, using the standard astronomical formulas for the sun's position. The sun is up while its centre is less than 0.833° below the horizon, the usual definition of sunrise and sunset that allows for the atmosphere bending the light and for the size of the sun's disc. Between that and 6° below the horizon is civil twilight, shaded in blue: light enough outside to see, dark enough that street lights are on. Below 6° the row is shaded as night.

Working it out from the sun matters most where the hour of the day is a poor guide. In London on the June solstice the sky reaches civil twilight at 03:56 and the sun rises at 04:44, then sets at 21:22. In Reykjavik on the same day the sun never sinks more than about 2.4° below the horizon, so the row never turns to night at all, and in late December the sun climbs only about 2.4° above it. Near the equator the day barely changes through the year: Singapore's sunrise on the June solstice is 07:01 and its sunset 19:13, late on the clock because Singapore keeps a time zone well east of its longitude.

A time zone added on its own, such as UTC, has no single place to put the sun over, so its row is shaded by the clock instead: day from 06:00 to 17:59, night otherwise, with no twilight band.

Your list, saved and shared

Add a place by typing a city name, or pick a time zone from the list for anywhere not covered by a city. Remove one with its bin button. The list is saved in this browser automatically, so the page opens on your own clocks next time, and nothing about it leaves your device: there is no account, and nothing is uploaded.

The address bar always holds the list on screen, so Copy link gives you a link that opens the same clocks for someone else — handy for a team spread across several cities. Opening a link someone sent you does not quietly replace your own saved list: the page shows their clocks and asks whether to keep them or go back to yours. Copy times copies the current time in every place as plain text, one line each, ready to paste into a chat. The 12-hour or 24-hour choice is remembered for you and is not part of the link, since the person you send it to may read clocks the other way.

Time zones, names and daylight saving

Every time comes from the time zone database built into your browser, the same one your phone and computer use, so daylight saving changes are applied on the right dates for each place, in both hemispheres. That also means the gap to your own clock is not fixed: New York and London are usually five hours apart, but the US moves its clocks forward on the second Sunday in March, two or three weeks before Europe's last Sunday, and back on the first Sunday in November, a week after Europe. For those weeks New York is four hours behind London instead of five. The gap shown is always the one in force right now.

Where the browser only knows a zone by its offset, as with GMT+8 for Singapore, the row uses a proper name and abbreviation instead, such as Singapore Time (SGT) or India Standard Time (IST), for the best-known zones. Everywhere else it shows the browser's own abbreviation and the UTC offset.

To compare a time other than now, such as a meeting next Tuesday at 15:00 in your zone, use the time zone converter, which converts one chosen moment across several zones. For the sunrise and sunset times of a single city over a whole year, see the sunrise and sunset calculator.