How World Time Sync Works
A plain-English look at how we show you the correct local time for 700+ cities, handle daylight saving time automatically, and convert between any two zones — all in your browser, in real time.
1. Where the time comes from
Every clock on this site is calculated on your own device, not on our servers. We use the International Atomic Time standard delivered through UTC (Coordinated Universal Time) and your operating system's clock. That means the displayed time is always as accurate as the device you're holding — no round-trips to a slow server, no "last updated 5 minutes ago" lag.
2. Time zones and offsets
Each city is mapped to a time zone with a known UTC offset — for example, London is UTC+0 in winter and UTC+1 in summer, while New York is UTC−5 / UTC−4. We apply the offset to the current UTC moment to produce the local time you see. When you open a city page, the page already knows its zone, so the clock is correct the instant it loads.
3. Daylight Saving Time, handled for you
Daylight Saving Time (DST) is the headache of modern scheduling. We store the DST rules for every supported zone, including the exact start and end dates for each year. When a region switches (say, the U.S. in March or the E.U. in late March), the offset updates automatically — you never have to remember whether it's EST or EDT this week.
4. Converting between two cities
Our meeting planner and timezone converters work by taking the UTC moment for City A, then re-applying City B's offset. Because both sides are anchored to the same UTC reference, the conversion is always consistent — even across the International Date Line, where one city might already be "tomorrow."
5. Your privacy by design
We don't ask you to log in and we don't build profiles. Time calculation happens locally in your browser; we only use anonymous analytics and (with your consent, via standard ad cookies) show contextual ads to keep the service free. Read the details in our Privacy Policy.
Quick answers
- Is it really live? Yes — the clock ticks every second from your device's own time.
- What if my phone clock is wrong? The site inherits your device time, so fix the device clock and the page follows.
- Does it work offline? Once loaded, the clock keeps running without a connection; only analytics and ads need the network.
- How many cities? Over 700, across every populated continent and major time zone.