Timezone Converter
Convert time between any two world timezones instantly.
The Timezone Converter lets you instantly convert any date and time from one world timezone to another, with full DST awareness.
Understanding Timezones and DST
How timezones work
The world uses 38+ unique UTC offsets, ranging from UTC-12 to UTC+14. Each timezone defines how many hours and minutes its local time differs from Coordinated Universal Time (UTC). When you convert between timezones, you add or subtract the difference in their UTC offsets to find the equivalent moment in time.
Daylight Saving Time (DST)
Many countries shift their clocks forward by one hour in spring and back in autumn to make better use of daylight. This means a timezone's UTC offset changes twice a year. For example, New York is UTC-5 in winter (EST) and UTC-4 in summer (EDT). This converter uses the JavaScript Intl API to automatically detect whether DST is active on the date you select.
Common use cases
Timezone conversion is essential for scheduling international meetings, understanding flight arrival times across date lines, reading server logs in your local time, and coordinating with remote teams across continents. Always double-check the date when crossing the International Date Line, as the day can shift by one.
Target time = Source time + (Target UTC offset − Source UTC offset) Frequently Asked Questions
Does this converter handle Daylight Saving Time automatically?
Yes. The converter uses your browser's built-in Intl API, which applies the correct DST rules for each timezone on the exact date you enter. The DST indicator card tells you whether DST is active in the target timezone.
How many timezones are supported?
The converter loads all timezones supported by your browser via Intl.supportedValuesOf('timeZone'), which typically includes 400+ IANA timezones covering every country and territory in the world.
Can I convert time for a past or future date?
Yes. The date and time picker lets you enter any date, not just today. DST rules are applied correctly for the specific date you choose, so historical and future conversions are accurate.
Why does crossing the International Date Line change the day?
Timezones on either side of the Date Line (UTC+12 to UTC+14 on one side, UTC-12 on the other) can differ by nearly 24 hours. When converting from, say, Los Angeles to Auckland, the result is often a day later because New Zealand is about 19–23 hours ahead depending on DST.
What is UTC and why is it used as a reference?
UTC (Coordinated Universal Time) is the global time standard with no DST shifts. All other timezones are expressed as offsets from UTC (e.g. UTC+5:30 for India, UTC-8 for US Pacific). It is used as a reference because it never changes, making time calculations unambiguous.
What is the formula for timezone conversion?
Target time = Source time + (Target UTC offset − Source UTC offset). For example, converting 3:00 PM New York (UTC-5) to London (UTC+0): 3:00 PM + (0 − (−5)) = 3:00 PM + 5 hours = 8:00 PM London time. DST shifts the relevant UTC offset by 1 hour when active.