Time Zone Converter
Current Time
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UTC offset: --
Converted Time
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UTC offset: --
Time Difference
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How Time Zone Conversion Works
The world is divided into time zones, each defined as an offset from Coordinated Universal Time (UTC). UTC replaced Greenwich Mean Time (GMT) as the world's time standard and is maintained by a network of atomic clocks worldwide. Most time zones are whole-hour offsets from UTC, but several regions use half-hour or even quarter-hour offsets, such as India (UTC+5:30), Iran (UTC+3:30), and Nepal (UTC+5:45).
Daylight Saving Time (DST) adds another layer of complexity to time zone conversions. When DST is active, clocks are set forward by one hour, changing the UTC offset. Not all countries observe DST, and those that do change at different dates. Countries in the Southern Hemisphere shift at opposite times of the year from Northern Hemisphere countries. This means the time difference between two cities can change multiple times throughout the year.
This converter uses the browser's built-in Intl.DateTimeFormat API with IANA time zone identifiers (e.g., "America/New_York", "Asia/Tokyo"). This approach automatically handles all DST transitions past, present, and future, as the time zone data is maintained by the browser and operating system. Select any two cities from the dropdown to see their current times, UTC offsets, and the time difference between them. You can also set a specific date and time to see what it corresponds to in another city.
Frequently Asked Questions
What is UTC and how do time zones work?
UTC (Coordinated Universal Time) is the primary time standard used worldwide. Time zones are defined as offsets from UTC, ranging from UTC-12 to UTC+14. Most time zones are whole-hour offsets, but some like India (UTC+5:30) and Nepal (UTC+5:45) use half-hour or quarter-hour offsets.
How does daylight saving time affect time zones?
DST shifts clocks forward by one hour in spring and back in fall, temporarily changing a region's UTC offset. Not all countries observe DST, and those that do may change on different dates. This converter uses Intl.DateTimeFormat with IANA time zones, which automatically accounts for current DST status.
Why do some countries have unusual time zone offsets?
Some countries choose non-standard offsets for practical reasons. India uses UTC+5:30 to keep the entire country on one time zone. Nepal uses UTC+5:45. These offsets better align noon with solar noon for their geographic locations.
How many time zones are there in the world?
There are 38 different time zone offsets in use worldwide, ranging from UTC-12 (Baker Island) to UTC+14 (Line Islands, Kiribati). Some regions within the same country use different time zones, such as the US spanning four time zones and Russia spanning eleven.