Time Zone Calculator
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How This Conversion Works
Every time zone in the world is defined as a fixed offset from Coordinated Universal Time (UTC) — for example, UTC-5 means "5 hours behind UTC." To convert a time from one zone to another, this calculator first subtracts the source offset from the entered time to get the equivalent UTC time, then adds the destination offset to that UTC time: destination time = source time - source offset + destination offset. If the result crosses midnight, the date rolls forward or backward a day accordingly, which is why the "Day Change" row is shown separately from the clock time.
Offset-Based, Not a Full IANA Time Zone Database
This tool converts between fixed UTC offsets (like UTC-5 or UTC+1) that you select directly, not between named geographic time zones with historical daylight saving time (DST) rules. A real-world location's offset can change twice a year when DST starts or ends, and some regions have changed their rules or abolished DST entirely over the decades. Because there's no reliable way to look up historical or future DST transitions without a full time zone database, treat the offsets here as the zone's current, standard UTC offset (e.g. US Eastern Time is listed as its winter/standard UTC-5, not summer UTC-4) — always double-check whether DST is in effect for your specific dates and locations before relying on the result for anything time-sensitive like flights or meetings.
Related Tools
Need to work out elapsed hours instead of converting a clock reading? Try the time duration calculator. If you're counting whole days between two dates rather than clock time, the day counter is the better tool.
Frequently Asked Questions
Does this calculator account for daylight saving time automatically?
No. It converts between fixed UTC offsets that you choose (like UTC-5 or UTC+1), not named geographic zones with historical DST rules. The listed offsets represent each zone's standard (non-DST) time, so you should manually pick the DST-adjusted offset (e.g. UTC-4 instead of UTC-5 for US Eastern in summer) if your date falls within a region's daylight saving period.
Why does the result sometimes show a different date than what I entered?
Converting between UTC offsets can push the clock time past midnight or before 00:00, which rolls the calendar date forward or backward a day. The "Day Change" row tells you exactly how many days shifted and shows the resulting weekday and date so you don't have to work it out by hand.