World Time Zone Converter

How the world clock works

The timeline is the heart of the tool. The reference city's day runs left to right in 24 hourly columns, and each city sits on its own row. Because every row is aligned to the same instant, a vertical slice of the grid is a single moment seen from different parts of the world — so you can literally see that it is lunchtime in São Paulo, breakfast in Berlin and midnight in Tokyo.

Hover or tap any column to select it, and the summary below names the time in every city in plain language. Business hours are shaded automatically, weekends are marked, and a live "now" line tracks the current moment so the view is always honest about where the day actually is.

How many time zones are there?

The short answer is that there are 24 whole-hour offsets, a handful of 30- and 45-minute offsets, and roughly 600 named IANA zone identifiers describing them. In practice most people mean one of about 38-40 usable zones when they ask how many time zones the world has.

The IANA identifiers exist because a single offset is not enough. "America/New_York" covers 12 US states and shows DST rules that differ from Arizona's neighbours; "Europe/London" encodes the fact that Britain's clocks follow the EU rule but its summer time is called BST rather than CEST. Each identifier is a precise contract about offset, daylight saving rules and the exact minutes of the transition.

Why the offsets are not evenly spaced

Most zones are whole hours from UTC, but a handful sit on 30- or 45-minute boundaries because their local solar time was standardised on a meridian that does not fall on an hour. India (+5:30), Nepal (+5:45), Sri Lanka (+5:30), Western Australia's Eucla (+8:45), the Chatham Islands (+12:45), Iran (+3:30) and the Marquesas Islands (−9:30) are the familiar examples.

This is why a converter that only handles whole hours is subtly wrong for a large part of the planet. Everything on this site is computed to the minute, so a 09:00 meeting in London becomes 14:30 in Delhi, not 14:00.

• UTC+5:30 — Delhi, Mumbai, Chennai, Kolkata, Colombo
• UTC+5:45 — Kathmandu
• UTC+8:45 — Eucla, Western Australia
• UTC+9:30 — Marquesas Islands, French Polynesia
• UTC+12:45 — Chatham Islands, New Zealand
• UTC−9:30 — Gambier Islands

The International Date Line and the date flip

The 180th meridian separates two calendar days. When you travel east across it you add a day, and west you subtract one. That is why a 09:00 Monday meeting in Los Angeles can be 05:00 Tuesday in Auckland — and why the same message in a chat thread can look like it was sent on a different day.

The line is not straight. It detours around Kiribati, Samoa and New Zealand so that each country stays on a sensible side of it. The extremes are Kiritimati (UTC+14, the earliest time on Earth) and the islands around Midway (UTC−11, the latest). Together they create a 25-hour span of real time on the planet.

Daylight saving around the world

Roughly two billion people in more than a hundred countries change their clocks twice a year, and the pattern is not simple. Most of the northern hemisphere shifts in March and November; the southern hemisphere shifts the other way, in October and April, so London and Sydney disagree about the season for about half the year. Morocco suspends daylight saving during Ramadan, Iran and Chile have changed their rules repeatedly in recent years, and Paraguay moved to permanent summer time in 2024.

Because the rules change per zone and per date, a converter that hardcodes offsets goes wrong twice a year. Reading the live IANA database means a London-to-Sydney gap of 9 hours in one season and 11 in the other is handled without any maintenance.