What time is it around the world?

Why time differences are not fixed numbers

Ask how far ahead London is of New York and the usual answer is five hours. That is right for most of the year and wrong for about three weeks of it. The United States moves its clocks forward on the second Sunday in March; the European Union waits until the last Sunday in March. In the gap between those two dates the difference is four hours, not five. The same thing happens in reverse in autumn, when the US falls back on the first Sunday in November and the EU has already done so a week earlier.

Southern hemisphere zones invert the problem. When Sydney enters daylight saving in October, the northern hemisphere is leaving it, so the Sydney–London gap swings by two hours over a few weeks rather than one. Meanwhile a large share of the world — India, China, Japan, Singapore, most of Africa and South America — does not observe daylight saving at all, so any pairing that crosses between an observing and a non-observing zone has a difference that changes even though only one side moved.

Every clock and every difference on this site is computed from the current instant against the target zone’s live rules, so these transition weeks resolve correctly without you tracking any of the dates above. Where a page also lists a standard-time difference, it is labelled as such.

A note on abbreviations

Time zone abbreviations are not unique. CST means US Central Standard Time at UTC−6 and also China Standard Time at UTC+8 — a fourteen-hour error if you pick the wrong one. IST is India Standard Time at UTC+5:30, Irish Standard Time at UTC+1, and Israel Standard Time at UTC+2. Where this site uses an abbreviation it names the country and IANA zone next to it, and it is worth confirming which one your counterpart means before you put a meeting in the calendar.

More on data sources and known limits on the about page.