Time Zone Converter
Convert a date and time between any two time zones.
Date & Time
From
To
Converted Time
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Pick a date and time to convert
How this calculator works
Time zone offsets aren't fixed — they shift with daylight saving time, and different countries switch on different dates. This looks up the real offset for both zones on the exact date you picked, so a conversion in July can differ from the same conversion in January even for the same two cities.
Where the offset data comes from
Offsets are read directly from your browser's built-in IANA time zone database via the JavaScript Intl API, the same data source operating systems and most software use, rather than a hardcoded table on this page. That's also why the list includes zones by city name (like Asia/Kolkata) instead of ambiguous abbreviations like IST — several unrelated zones share the same three-letter abbreviation, but a city-based IANA name always identifies exactly one zone with its own history of offset and daylight-saving changes.
Not every zone is offset by whole hours
A handful of zones sit on a half-hour or 45-minute offset rather than a full hour — India Standard Time is UTC+5:30 and Nepal is UTC+5:45, for example. Converting into or out of one of these zones can land the result on a time like 9:45 or 2:15 rather than a clean hour mark, which is expected behavior, not a rounding error.
Recurring meetings across zones can drift
Because the US, EU and other regions each switch daylight saving time on their own schedule (and on different calendar dates from each other), a meeting that's a 3-hour gap in summer can become a 2 or 4-hour gap for a few weeks around the switchover in spring or autumn. Always double-check the specific date you care about rather than assuming today's offset holds year-round — this is exactly why this tool asks for a date, not just a time.
Frequently Asked Questions
Does this converter account for daylight saving time?
Yes — conversions use each timezone's current UTC offset, which automatically reflects daylight saving time where applicable for the date you select.
Can I convert between more than two time zones at once?
Pick any source and target timezone pair — for comparing several zones simultaneously, run multiple conversions from the same source time.
Is the conversion based on my device's clock?
Your local timezone is detected automatically as a starting point, but you can override either side to any timezone regardless of where you actually are.
Why are some converted times not on the hour, like 9:45?
Some zones use a half-hour or 45-minute offset instead of a full hour — India Standard Time is UTC+5:30 and Nepal is UTC+5:45, for example. A converted time landing on a non-hour mark is expected for these zones, not a rounding error.
Where does the time zone offset data come from?
It's read from your browser's built-in IANA time zone database via the JavaScript Intl API — the same data source most operating systems and software use — rather than a hardcoded table, so it stays accurate as daylight saving rules change.
Why does this use city names like Asia/Kolkata instead of abbreviations like IST?
Abbreviations like IST are ambiguous — several unrelated zones around the world share the same three-letter code. A city-based IANA name always identifies exactly one time zone with its own specific offset and daylight-saving history.