Why a page per city
The world clock is the right tool when you want several places side by side and you intend to keep it open. These pages are for the other case: you want one answer, now, about one city.
Every one of them reads the IANA time zone database in your own browser, so the offsets and abbreviations are whatever is currently in force rather than numbers typed into a page. That distinction matters more than it sounds — Mexico abolished daylight saving in 2022 and Brazil in 2019, and any page with the old offsets written into it has been wrong ever since.
The half-hour offsets
Not every zone is a whole number of hours from UTC. India runs on a thirty-minute offset, Nepal on forty-five, and parts of Australia and Canada use half-hour zones too. Any tool that assumes whole hours will be wrong for well over a billion people.
Which cities change their clocks
Roughly half the cities listed here observe daylight saving and half do not, and the split is not the one most people expect. Japan, South Korea, China, Hong Kong, Singapore, India, the Gulf and most of Africa have never used it or abandoned it decades ago. Russia stopped in 2014, Turkey in 2016, Brazil in 2019 and Mexico in 2022.
That matters because the gap between two cities is only fixed when both of them change their clocks on the same dates. London and Paris are always exactly one hour apart. London and Tokyo are not — the difference moves by an hour twice a year, entirely because of what London does. Each city page states plainly which side of that line it is on.
The southern hemisphere runs the other way
Sydney and Auckland put their clocks forward in September and October, when Europe and North America are putting theirs back. For a few weeks either side of those changeovers the difference between Sydney and London moves by two hours rather than one, which is the single most common cause of a mis-scheduled call between them.
Why the times here are never stale
Every page reads the time zone database built into your own browser rather than a number written into the page. When a country changes its rules, your browser gets the update and these pages change with it — no edit required here, and nothing to go out of date.