World Clock
See the current time in 8 major cities including New York, London, Tokyo, and Sydney.
Updates every second and shows date and UTC offset for each.
Time zones divide the world into regions that observe a uniform local time. They are based on UTC (Coordinated Universal Time), the modern successor to Greenwich Mean Time (GMT).
Time conversion formula: Target Time = Source Time + (Target UTC Offset − Source UTC Offset)
If the result goes past midnight, add or subtract 24 hours and adjust the date accordingly.
UTC offset definition: Each time zone is expressed as UTC+X or UTC−X.
- UTC+0: London (winter), Accra, Reykjavik
- UTC−5: New York (EST), Miami, Toronto
- UTC+1: Paris (CET), Berlin, Rome
- UTC+8: Beijing, Singapore, Perth
- UTC+9: Tokyo, Seoul
- UTC+5:30: Mumbai, New Delhi (note the half-hour offset)
- UTC+5:45: Kathmandu (note the quarter-hour offset)
Worked example: It is 3:00 PM (15:00) in New York (UTC−5). What time is it in Tokyo (UTC+9)? Difference = UTC+9 − (UTC−5) = +14 hours Tokyo time = 15:00 + 14 = 05:00 the next day
Daylight Saving Time (DST): Many countries shift clocks forward by 1 hour in summer. The US moves to EDT (UTC−4) in summer; the UK moves to BST (UTC+1) in summer. DST transitions do not occur on the same date worldwide — causing the offset between two DST-observing countries to change temporarily during transition weeks.
Countries that do not observe DST: China, Japan, India, most of Africa, and most equatorial nations. This means the offset between these locations and DST-observing countries changes by 1 hour seasonally.