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Timezone Converter

Convert a date and time from one timezone to another. Supports all IANA timezones including UTC, GMT, and regional zones.

World clock

About Timezone Conversion

The world is divided into time zones based on UTC (Coordinated Universal Time) offsets. Each time zone is defined by an offset from UTC — for example, UK time in summer is UTC+1 (BST), Eastern US time is UTC-5 (EST) or UTC-4 in summer (EDT). This tool converts a date and time from one zone to another and shows a live world clock for common cities.

UTC offsets vs named time zones

A UTC offset (like +05:30) is a fixed offset that does not account for Daylight Saving Time. A named time zone (like Asia/Kolkata or Europe/London) uses the IANA Time Zone Database and automatically handles DST transitions. Always prefer named time zones in software over fixed UTC offsets to avoid DST bugs.

Daylight Saving Time (DST)

Most countries that observe DST move their clocks forward one hour in spring and back one hour in autumn. The UK moves from GMT (UTC+0) to BST (UTC+1) in late March and back in late October. The US moves between EST (UTC-5) and EDT (UTC-4). Not all countries observe DST — Japan, India, and most of Africa do not. This means the offset between two zones can vary by an hour depending on the time of year.

Common time zone identifiers

  • Europe/London — UK (GMT in winter, BST in summer)
  • America/New_York — US Eastern (EST/EDT)
  • America/Los_Angeles — US Pacific (PST/PDT)
  • Asia/Tokyo — Japan Standard Time (JST, UTC+9, no DST)
  • Asia/Kolkata — India Standard Time (IST, UTC+5:30, no DST)
  • Australia/Sydney — Australian Eastern (AEST/AEDT)

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Frequently asked questions

What timezone database does this use?
This tool uses the IANA Time Zone Database (also known as the Olson database), which is the standard used by all major operating systems and programming languages. It covers all historical timezone changes and daylight saving time rules.
What is UTC offset?
UTC offset is the difference between a timezone and Coordinated Universal Time (UTC). For example, UTC+1 is one hour ahead of UTC. The offset changes during daylight saving time.