Time Zone Converter

UTC (Coordinated Universal Time) is the primary time standard — all zones are expressed as UTC+ or UTC− offsets. It does not observe DST. Examples: New York UTC-5 (UTC-4 summer), London UTC+0 (UTC+1 summer), Madrid UTC+1 (UTC+2 summer), Tokyo UTC+9 (no DST). UTC replaced GMT as the international standard but they are practically identical.

DST advances clocks by 1 hour in summer to extend evening daylight. Countries with DST: most USA, Canada, Europe (last Sunday March–October), Australia (Oct–Apr). Countries without DST: China, Japan, India, Russia, most of Africa and SE Asia, Arizona (USA). DST dates differ by hemisphere — converter is DST-aware for any date.

Normally 5 hours (NY behind London). NY is UTC-5/UTC-4 (summer); London is UTC+0/UTC+1 (summer). Because the US and UK switch DST on different dates, there are 2–3-week periods in spring (4-hour difference) and autumn (6-hour difference). When it's 9am in New York (EST), it's 2pm in London (GMT).

Best practices: (1) Use UTC for internal communication; (2) Find a "golden window" where 8am–6pm overlaps in each zone; (3) New York + London: 9am–1pm EST works; (4) New York + Singapore (13h apart): no comfortable overlap — one team attends outside business hours; (5) Always include the timezone abbreviation (9am EST, not 9am); (6) Use the World Clock / Meeting Planner for 12 zones at once.