About ExactTime

ExactTime is a free, browser-based world clock. It shows the current time down to the second for your own location and for hundreds of cities across every inhabited time zone, alongside the calendar date, the ISO week number, how much of the day has already elapsed, and — if you choose to share your location — today's sunrise and sunset. There is no account to create, nothing to install, and no dashboard to configure. You open the page and the time is already there, ticking.

The site is operated by an independent publisher. We are not a government laboratory, a national metrology institute, or an official timekeeping authority, and we do not claim to be. ExactTime is an independent time reference: a clear, fast, readable presentation of time information that is already available on your own device and in the public time zone database that virtually every operating system uses.

Why accurate time matters

Most of the day, being a minute out costs nothing. Then it suddenly costs a great deal: a job interview at 14:00 in a city two zones away, a flight that closes boarding forty minutes before departure, an exam portal that locks, an auction that ends, a market that opens, a medication taken on a strict interval, a payment cut-off, a call with colleagues on three continents. Time is the one coordinate everybody has to agree on, and it is also the one people most often get wrong — usually not because a clock was inaccurate, but because a time zone, a daylight saving switch, or an ambiguous abbreviation was misunderstood.

That is why ExactTime is not only a clock. It is also a small library of plain-English guides explaining the parts of timekeeping that trip people up: what UTC really is, how daylight saving time works, why the international date line zigzags, and how to schedule across time zones without a costly mistake.

How the times on this site are calculated

Everything runs in your browser. ExactTime reads the current instant from your device's system clock, then converts that instant into local wall-clock time for each city using the browser's built-in internationalisation engine (the standard Intl API), which is backed by the IANA time zone database — the same maintained dataset that ships with Windows, macOS, Linux, Android and iOS.

This matters for two reasons. First, daylight saving time is handled automatically: because each city is stored as an IANA zone identifier such as Europe/Berlin or America/New_York rather than as a fixed offset, the correct offset is derived for the exact moment being displayed, including on the days clocks shift. Second, the offsets you see reflect current published rules rather than a hard-coded table that quietly goes stale when a country changes its policy.

The consequence is worth stating plainly: the accuracy of the reading depends on your own device clock, while the time zone conversion depends on the tz database. If your device clock drifts, every city on the page drifts with it. Keeping automatic network time synchronisation enabled on your phone or computer normally keeps you within a fraction of a second. Our disclaimer explains the limits of what this site should be relied on for.

Who ExactTime is for

Remote teams and freelancers checking whether a colleague is awake. Travellers working out what time they will land. Students and teachers with deadlines in another country. Traders, gamers and sports fans waiting for an event that was announced in a zone they do not live in. Developers sanity-checking an offset or a DST boundary. And anyone who simply wants a large, honest clock on a second screen.

How we keep the site free

ExactTime is supported by advertising. Ad space is clearly labelled and kept away from the clock itself, so a sponsored message can never be mistaken for the time. We describe what advertising partners may collect, and how to opt out, in our Privacy Policy. We do not sell personal data, and we do not require you to identify yourself to use anything on the site.

Corrections and contact

If a city is missing, an offset looks wrong, or a guide contains an error, we want to know. Write to hbatchi2002@gmail.com or use the contact form. Corrections to factual content are made promptly and without fuss.