WORLD CLOCK & DAYLIGHT · RUNS IN YOUR BROWSER
Pick the cities you actually care about and see them side by side: current local time, sunrise, sunset, how long the day is, and a plain waking-hours label so you know whether a call is a kindness or an alarm clock.
Nothing is uploaded and there is no network request at all. Sunrise and sunset are computed here, in this tab, from the US Naval Observatory's published almanac algorithm.
| City | Local time | Now | Sunrise | Sunset | Daylight | vs. you | Remove |
|---|
No cities selected. Add one below, or .
| Value | How |
|---|---|
| Local time | Your browser's own IANA time zone database, so daylight saving is already handled for every city |
| Sunrise / sunset | The Sunrise/Sunset Algorithm from the Almanac for Computers, 1990 (Nautical Almanac Office, US Naval Observatory), using city-centre coordinates — accurate to roughly a minute outside the polar circles |
| Daylight length | The interval between the two, for that city's own local calendar day |
| Waking-hours label | A courtesy heuristic on the local clock alone: asleep before 07:00 and from 22:00, early to 09:00, working hours to 17:00, evening to 22:00 |
| vs. you | The difference between each city's current UTC offset and your own, so half-hour and three-quarter-hour zones read correctly |
The waking-hours label knows nothing about weekends, public holidays, shift work, or the person's actual job. It is a nudge before you dial, not a fact about them.
From the Sunrise/Sunset Algorithm published in the Almanac for Computers, 1990 (Nautical Almanac Office, United States Naval Observatory) — the public-domain algorithm behind most open-source sunrise calculators. It needs only a date, a latitude and a longitude, all of which are already on this page, so the whole computation runs in your browser. It is accurate to roughly a minute outside the polar circles.
Three ordinary reasons. The almanac algorithm is accurate to about a minute, not to the second. This tool uses city-centre coordinates, and sunrise genuinely differs across a large metropolitan area. And published times sometimes measure a slightly different event — the sun's upper limb clearing a flat horizon versus the centre of the disc — which shifts the answer by a minute or two. None of these matter for knowing whether it is light there; none of them should be relied on for navigation, aviation, or religious observance.
They are a plain courtesy heuristic about waking hours based only on the local clock: asleep before 07:00 and from 22:00, early until 09:00, working hours until 17:00, evening until 22:00. They are not a claim about anyone's actual schedule, working week, or public holidays, and they do not know about weekends. Treat them as a nudge before you call, not as a fact about the person.
No. There is no account, no cookie, no analytics vendor and no network request of any kind — the page ships the city list and the solar maths and computes everything locally. The cities you pick are remembered in your own browser's local storage so the page opens the same way next time, and anonymous feature counters are kept in the same place. Both can be cleared with the button in the footer, and Do Not Track and Global Privacy Control are honoured.
Yes. The Copy share link button puts the current selection into the URL, so the person you send it to opens the same cities in the same order. The link carries nothing but the city names — no identifier, and nothing about you.
A phone's world clock shows the time in a city; it usually does not show sunrise, sunset, daylight length, or whether that time is a reasonable one to call. See this tool vs. your phone's built-in world clock for the comparison.
Because Indian Standard Time is anchored to a meridian near the country's geographic centre rather than rounded to the nearest hour, and the country has run on one national clock since 1906 despite spanning roughly two hours of longitude. See why India's time zone is UTC+5:30 for the full explanation, including the other half-hour and 45-minute zones around the world.