Time Zone Guides
The rest of this site tells you what time it is. These pages explain why it is that time, which turns out to involve rather more politics, tea plantations and litigation than you would expect from a subject that looks like geometry.
How time zones got the way they are
Why India Has Only One Time Zone
India is nearly 3,000 kilometres wide and runs a single clock on an awkward half hour. Where UTC+5:30 comes from, why Assam's tea estates keep their own unofficial time, and why every proposal to split the country into two zones has been rejected.
The World’s Strangest Time Zone Offsets
Three places on Earth use 45-minute offsets, the inhabited world spans 26 hours rather than 24, and Spain runs an hour ahead of where the sun says it should. A tour of everything that breaks the whole-hour assumption.
Why the International Date Line Is Not a Straight Line
No treaty defines it and no authority maintains it, which is why countries can and do move it. Kiribati wrapped it around itself in 1995, Samoa deleted 30 December 2011 entirely, and two islands four kilometres apart sit 21 hours apart.
Daylight saving, and what it breaks
The Four Weeks a Year When London and New York Are Not Five Hours Apart
The US and Europe change their clocks on different dates, so for about four weeks a year the familiar difference is wrong by an hour. The exact windows, why the southern hemisphere makes it worse, and the hour that happens twice.
Why Your Recurring Meeting Shows the Wrong Time Twice a Year
A standing call that quietly moves in March or October is not a calendar bug. There are three ways to store a time and only one of them survives a transition. What goes wrong, why recurrence multiplies it, and how to set events so it stops happening.
The Countries That Gave Up on Daylight Saving
Russia abolished it twice in opposite directions within four years. Turkey kept the summer, Mexico kept a border exception, and the EU voted to stop in 2019 and then did not. Why agreeing to stop is easy and agreeing what to keep is not.
The machinery underneath
UTC, GMT and Zulu: What the Difference Actually Is
One is an atomic time scale, one is an astronomical one that turned into a time zone, and one is a letter. Leap seconds, why UTC is spelled that way, and the mistake almost everyone in Britain makes for half of every year.
Who Decides What Time It Is Where You Are
No treaty governs time zones. A volunteer-maintained database does, it names zones after cities for a specific reason, and in 2011 a lawsuit from an astrology software company briefly took the whole thing offline.
Looking for a specific time instead?
The interactive map colours every region by its current offset, the world clock lists live local times for cities worldwide, the time difference pages compare two cities and work out when their working days overlap, and the country index shows which zones each country uses.