Time Zone Converter

Time Zones: A Rational Idea Wearing Political Trousers

Built and verified by Andrius R. · Updated June 2026

In principle, time zones are simple: Earth turns 360° in 24 hours, so each 15° of longitude is one hour. In practice the map is a century of politics, commerce and daylight-saving quarrels — which is why converting times correctly is harder than the geometry suggests.

UTC: the anchor everything hangs from

Every zone is an offset from UTC (Coordinated Universal Time, the atomic-clock successor of GMT): Lithuania is UTC+2 (winter) / UTC+3 (summer), New York UTC−5/−4, Tokyo a steady UTC+9. The reliable conversion method is two hops, never one: local → UTC → other local. Converting directly between two DST-observing zones is where mental arithmetic dies, because the offsets each change on different dates.

Daylight saving: where the bugs live

Bonus chaos: the Southern Hemisphere shifts opposite (their summer is our winter), large players skip DST entirely (Japan, China, India, most of Africa), and within countries it splits — Arizona ignores DST while the Navajo Nation inside it observes it.

The map's famous eccentricities

• Half- and quarter-hour zones: India runs UTC+5:30, Iran +3:30, Nepal +5:45 — compromises between geography and neighbors. (India's single zone also means the sun behaves very differently in Mumbai and the far east of the country at the same clock time.)
• China: one zone (UTC+8) for a country spanning five geographic hours — in far-western Xinjiang, "noon" sun arrives around 14:00–15:00 on the clock.
• The widest day: with UTC+14 (Kiribati's Line Islands) and UTC−12 both inhabited, the planet hosts 26 hours of "today" at once — for a few hours, three calendar dates coexist on Earth.
• The date line zigzags for politics: Kiribati bent it in 1995 so its whole nation shared a date (and caught the millennium's first sunrise); Samoa deleted 30 December 2011 entirely, jumping across the line to align its week with Australia and New Zealand.

Scheduling across zones without casualties

1. Name the zone, every time. "3 PM Tuesday" in an international thread is a coin-flip; "15:00 EET (Vilnius)" is information. Better still, state both ends: "15:00 Vilnius / 8:00 New York."
2. Beware silent-conversion tools: calendar invites convert automatically (good) but emailed times don't (bad) — the mismatch between the two is the classic missed-meeting generator.
3. Flights live in local times: a departure and arrival are each printed in their own airport's zone, which is how a 10-hour flight can "land before it took off" crossing the date line westbound—east, and why layover math needs this converter more than any meeting does.
4. For repeating events, pick the anchor consciously: anchored to Vilnius, your New York colleagues shift twice a year; anchored to UTC, everyone shifts. There's no neutral choice — only an explicit one.