Free Time Zone Converter
Convert times between 30+ world time zones. Includes live world clock with day/night indicator.
Convert Time
World Clock — Current Time
How Time Zones Work
The world is divided into 24 primary time zones, each roughly 15 degrees of longitude wide. All zones are defined as offsets from UTC (Coordinated Universal Time). UTC+0 runs through Greenwich, London. Moving east adds hours (UTC+1, +2, etc.) and moving west subtracts them (UTC-5 for New York, UTC-8 for Los Angeles). Some zones use half-hour or 45-minute offsets — India is UTC+5:30 and Nepal is UTC+5:45. Daylight saving time shifts clocks forward by one hour in summer in many countries, complicating conversions.
Major Time Zone Offsets
Daylight Saving Time (DST)
DST shifts clocks forward one hour in spring and back in autumn to maximise evening daylight. In the UK, clocks go forward on the last Sunday of March (GMT to BST) and back on the last Sunday of October. The US changes on the second Sunday of March and first Sunday of November. Not all countries observe DST — Japan, China, India, and most equatorial nations do not. During DST transitions, time zone differences between countries can temporarily change by an hour.
Tips for Scheduling Across Time Zones
- Use UTC as the reference: When scheduling with people in multiple zones, state the UTC time and let each person convert locally.
- Overlap window: For UK-US meetings, the best overlap is 2pm-5pm GMT (9am-12pm EST). For UK-Australia, try 8am-9am GMT (7pm-8pm AEDT).
- Avoid Fridays and Mondays: Due to the International Date Line, Friday evening in Australia is Friday morning in the US — but it can be confusing when one side's weekend has started.
- Use ISO 8601: Write dates as YYYY-MM-DD to avoid DD/MM vs MM/DD confusion across cultures.
The International Date Line
The International Date Line (IDL) runs roughly along the 180th meridian through the Pacific Ocean. When you cross it westward, you skip forward one day. When you cross eastward, you go back one day. The line zigzags to keep certain island nations on the same calendar date. Samoa famously moved west of the date line in 2011, skipping December 30th entirely to align with trading partners in Australia and New Zealand.
History of Time Zones
Before time zones, every town set clocks by local solar noon. Railway expansion in the 1800s made this chaotic — a traveller crossing England could encounter dozens of slightly different local times. In 1884, the International Meridian Conference established Greenwich as the prime meridian (0 degrees longitude) and proposed 24 standard time zones. The system was gradually adopted worldwide over the following decades.
Related Tools
Frequently Asked Questions
Enter the time, select source and target zones above, click Convert. The tool calculates using UTC offsets.
Coordinated Universal Time — the global standard. All time zones are offsets from UTC. London is UTC+0 (winter) or UTC+1 (summer).
5 hours. New York is UTC-5 (winter) vs London UTC+0. Both shift for DST so the gap usually stays 5 hours.
No. Japan, China, India, most of Africa and South America don't. The UK, EU, US, Canada and Australia do.
A line in the Pacific at ~180° longitude. Cross westward = next day. Cross eastward = previous day.
