Everyday world · Updated September 2026
World time zones
Time zones are offsets from UTC. India is UTC+5:30. The UK uses GMT/BST. The International Date Line sits near 180°. Why some countries have half-hour zones.
Civil clocks follow time zones — usually a whole or half hour ahead of or behind Coordinated Universal Time (UTC). UTC replaced GMT as the scientific standard; UK winter time is still called GMT in daily speech.
India uses a single zone, IST, at UTC+5:30. China uses one zone (UTC+8) despite its width. The United States has several (Atlantic through Hawaii). Australia has several, some with half hours. The Learn desk has a “how calls and flights work” page; this page is the map and offset sheet.
The International Date Line runs near 180° longitude in the Pacific. Cross it east and you usually subtract a calendar day; west and you add one. That is why American Samoa and nearby islands can be on different dates.
World time zones — key facts (2026)
| Topic | Fact |
|---|---|
| Reference | UTC (Coordinated Universal Time) |
| India (IST) | UTC+5:30 |
| UK winter / summer | GMT (UTC+0) / BST (UTC+1) |
| US Eastern (standard) | UTC−5; daylight UTC−4 |
| China | UTC+8 nationwide |
| Australia East (AEST) | UTC+10; some states use daylight time |
| Date line | Near 180° in the Pacific |
| Half-hour zones (examples) | India, Iran, Afghanistan, parts of Australia |
Figures are the usual classroom and news-desk numbers for 2026. Border disputes and membership votes can change a count by one or two.
People also ask
What time zone is India in?
IST — UTC+5:30. One zone for the whole country.
Is GMT the same as UTC?
For civil use they match in the UK in winter. UTC is the precise standard; GMT is the older name.
Why does the date change in the Pacific?
The International Date Line keeps the calendar lined up with the Sun as you go around the world.