Tool

Timezone Converter

Enter a date and time in any timezone and see it converted to multiple timezones at once. Covers all IANA regions with automatic daylight saving time handling.

IANA timezone database

This tool uses the IANA timezone database (also called the tz database or Olson database), the most comprehensive and authoritative source of timezone rules. It covers the full history of UTC offsets and daylight saving time transitions for every timezone region in the world. Your browser's built-in Intl API provides access to this data without any additional libraries or network requests.

Daylight saving time (DST)

Daylight saving time shifts clocks forward by one hour in spring and back in autumn for regions that observe it. This converter automatically applies the correct DST offset for the selected timezone and date. For example, America/New_York is UTC-5 during Eastern Standard Time (EST) and UTC-4 during Eastern Daylight Time (EDT).

  • United States DST: second Sunday in March → first Sunday in November
  • European DST: last Sunday in March → last Sunday in October
  • Many countries (including China, Japan, India) do not observe DST
  • Unix timestamps are not affected by DST — they are always counted in UTC seconds

UTC offsets explained

A UTC offset describes how many hours and minutes a timezone is ahead of or behind UTC. UTC+00:00 is UTC itself. UTC+08:00 is 8 hours ahead (e.g. China Standard Time, Singapore, Perth). UTC-05:00 is 5 hours behind (Eastern Standard Time). Offsets range from UTC-12:00 to UTC+14:00.

  • UTC+00:00 — UTC, GMT, West Africa Time
  • UTC+01:00 — Central European Time (CET), West Africa Standard Time
  • UTC+05:30 — India Standard Time (IST, no DST)
  • UTC+08:00 — China Standard Time, Singapore, Philippine Time
  • UTC+09:00 — Japan Standard Time, Korea Standard Time (no DST)
  • UTC-05:00 — Eastern Standard Time (UTC-4 during EDT)

Frequently asked questions

What is the difference between UTC and GMT?
For everyday use, UTC and GMT are effectively the same — both sit at UTC+00:00. Technically, GMT is a timezone based on mean solar time at Greenwich, while UTC is an atomic time standard. Programming contexts almost always use UTC.
How does daylight saving time affect Unix timestamps?
Unix timestamps are not affected by DST because they are always counted in UTC seconds. DST only affects how a timestamp is displayed in local time. This converter applies the correct DST offset for the selected timezone and date.
What is an IANA timezone identifier?
An IANA timezone identifier (e.g. 'America/New_York', 'Asia/Tokyo') uniquely identifies a timezone region and its full history of UTC offsets and DST rules. They are maintained in the IANA Time Zone Database and supported by all major platforms.
Should I store UTC or local time in my database?
Always store UTC (or Unix timestamps) in your database and convert to local time only at display time. This avoids ambiguity during DST transitions and makes cross-timezone queries reliable.