Free Time Zone Converter

Convert times between any two world time zones. Plan meetings, coordinate teams, and never miss a call.

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Time Zone Converter
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What Is a Time Zone?

A time zone is a region of the globe that observes a uniform standard time. The world is divided into 24 primary time zones, each theoretically covering 15 degrees of longitude (since the Earth completes one 360-degree rotation in 24 hours). In practice, time zone boundaries zigzag to follow national and regional borders, so some zones have unusual offsets — India, for example, is UTC+5:30, and Nepal is UTC+5:45.

Time zones are generally described by their offset from Coordinated Universal Time (UTC), the world's primary time standard. UTC+0 corresponds roughly to the Greenwich Meridian in London. New York is UTC-5 in winter (Eastern Standard Time) and UTC-4 in summer (Eastern Daylight Time). Tokyo is UTC+9 year-round, as Japan does not observe daylight saving time.

How Daylight Saving Time Affects Conversions

Daylight Saving Time (DST) shifts clocks forward by one hour in spring and back in autumn in many countries. This means that the offset between two time zones can change by one or two hours depending on the time of year. For example, the difference between New York and London is 5 hours in winter but only 4 hours in summer, because both observe DST but switch on different dates. Some countries — including Japan, India, China, and most of Africa — do not observe DST at all.

Our converter accounts for DST automatically by using the IANA timezone database (the same database used by modern operating systems and browsers). When you enter a specific date, the converter correctly applies the UTC offset in effect on that date in each selected time zone.

Working Across Time Zones: Practical Tips

Managing schedules across time zones is a daily reality for remote teams, international businesses, and travelers. Here are strategies to reduce confusion and scheduling errors:

  • Communicate in UTC: When scheduling meetings with people across many zones, stating the time in UTC eliminates ambiguity. Everyone can convert from a known reference point.
  • Know your overlap hours: Identify the hours when both your time zone and your collaborator's are within business hours (9:00–17:00). This tool's Business Hours badge helps you check instantly.
  • Include the timezone abbreviation in invites: Always specify the timezone when sending calendar invites. "3 PM" without a timezone is ambiguous; "3:00 PM ET" is clear.
  • Beware of date changes: A meeting scheduled at 10 PM in Los Angeles is the next day in London. Always check whether the date changes, especially for late-evening calls.
  • Account for DST transitions: Meetings scheduled months in advance may shift by an hour when clocks change. Verify the converted time close to the meeting date.

Remote Work and International Meeting Planning

The rise of distributed remote work has made time zone awareness more critical than ever. A team with members in New York, London, and Singapore spans 13 hours in winter, making a single overlap window during standard business hours almost impossible. Teams in this situation often use a rotating schedule — alternating who takes the "off-hours" meeting — or rely heavily on asynchronous communication.

Meeting planning tools and this converter can help you identify the best windows. For a New York–London pair, the 9:00 AM – 1:00 PM New York window maps to 2:00 PM – 6:00 PM London, giving a comfortable four-hour overlap in winter. For New York–Mumbai, the only overlap within business hours is typically 8:30 AM – 9:00 AM New York, which is 7:00–7:30 PM Mumbai — a very narrow window requiring early starts in New York or late evenings in Mumbai.

Understanding UTC Offsets

UTC offsets are written as UTC±HH:MM. A positive offset (e.g., UTC+5:30 for India) means the local time is ahead of UTC — when it is noon in London (UTC), it is 5:30 PM in Mumbai. A negative offset (e.g., UTC-5 for New York in winter) means local time is behind UTC — when it is noon in London, it is 7:00 AM in New York. UTC itself has no offset and is sometimes labeled GMT (Greenwich Mean Time), though strictly speaking UTC and GMT are slightly different standards.

Some time zones have half-hour or quarter-hour offsets. India (UTC+5:30), Sri Lanka (UTC+5:30), Afghanistan (UTC+4:30), Iran (UTC+3:30), and Nepal (UTC+5:45) are the most commonly encountered. Australia's Central Standard Time is UTC+9:30. These irregular offsets can catch travelers and international schedulers off guard.

Frequently Asked Questions

When the UTC offset difference between two time zones spans midnight, the calendar date in the target zone will be different from the source zone. For example, 10:00 PM on Monday in Los Angeles (UTC-7) is 6:00 AM on Tuesday in London (UTC+1). The converter always shows the full date in the result so you can see whether a day change has occurred.

GMT (Greenwich Mean Time) is a historical time standard based on the mean solar time at the Royal Observatory in Greenwich, London. UTC (Coordinated Universal Time) is the modern international standard, kept by atomic clocks and adjusted with leap seconds. For practical purposes they are the same to within one second, and in everyday usage "GMT" and "UTC" are often used interchangeably. Official and technical contexts use UTC.

Best practice is to state the meeting time in UTC, plus your local time for reference. For example: "Team standup at 14:00 UTC (9:00 AM ET / 2:00 PM BST / 7:00 PM IST)." This lets each participant verify the correct local time without depending on any single zone being primary. Most calendar applications will automatically convert a UTC time to the user's local time zone.

In the United States and Canada, clocks spring forward on the second Sunday of March and fall back on the first Sunday of November. In most of Europe, clocks change on the last Sunday of March (forward) and the last Sunday of October (backward). Australia (except Queensland, WA, and NT) changes on the first Sunday of October (forward) and the first Sunday of April (backward). Because the change dates differ, the offset between US and European zones is different in March and November compared to the rest of the year.

This tool considers 9:00 AM to 5:00 PM (09:00–17:00) as standard business hours in the target time zone. If the converted time falls within this window, a green "Business Hours" badge appears. If it falls outside this window, a red "Outside Business Hours" badge appears. This gives you a quick visual indicator of whether your counterpart is likely to be available during normal working hours.

This converter uses the browser's built-in Intl.DateTimeFormat API, which relies on the IANA Time Zone Database — the same database used by operating systems, programming languages, and major calendar applications worldwide. It correctly handles all historical and current DST rules, half-hour offsets, and timezone boundary changes. Accuracy depends on your browser's timezone data being up to date, which it generally is in any modern browser.

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