Convert any date and time across world time zones instantly. Pick the source timezone, enter the date and time, and select target timezones to see the equivalent local time everywhere - useful for scheduling international meetings, calls and travel arrangements.
The value is interpreted as local civil time in the source zone - not necessarily your PC zone.
Same instant in America/New_York
Tue, 27 Oct, 2026, 08:34:00 pm
Check in Asia/Kolkata
Wed, 28 Oct, 2026, 06:04:00 am
UTC (ISO)
2026-10-28T00:34:00.000Z
Uses IANA zones via Intl only - no network calls. If a converted time looks off by one hour, check DST change dates for that region.
Time zones are the most underrated source of friction in international work. A 3 pm IST call sounds simple until you realise it's 4:30 am in San Francisco, 9:30 am in London, 5:30 pm in Singapore and 8:30 pm in Sydney - and that the US has DST, India does not, and Australia's east coast moves the other direction in the southern winter. Every international remote worker, founder, recruiter and consultant develops some intuition for these conversions, but for any specific date, doing the math by hand is error-prone enough that most people just look it up.
This converter uses the IANA tz database (the same one that powers macOS, Linux and most server software) via the browser's built-in Intl.DateTimeFormat. It handles every timezone, every daylight-saving rule, and every historical timezone change - so a meeting on November 5, 2025 (the day US DST ends) is computed correctly even though the offset between US and India shifts by an hour at 2 am local US time that day.
Enter the source date and time.
Select the source timezone (e.g. Asia/Kolkata for India).
Add one or more target timezones to see the equivalent times.
View the converted times alongside the day-of-week - useful for confirming weekday/weekend differences.
Use the swap or 'now' shortcut to compute conversions based on current time.
Each timezone is identified by a IANA name like Asia/Kolkata, America/New_York or Europe/London. The browser computes the UTC offset for the given date in each zone (accounting for daylight saving time rules in effect on that date), and then formats the equivalent local time. The conversion is exact down to the minute and respects historical timezone changes.
Target = Source UTC time + Target UTC offset
DST rules vary by country and by year. The US started DST on the second Sunday of March and ended it on the first Sunday of November (current rule, since 2007). The EU stops/starts DST on the last Sundays of March and October. India, China and Japan don't observe DST. Australia observes DST in some states but not others (Queensland, Western Australia, Northern Territory don't). The calculator handles all of these from the IANA database - you don't need to remember them.
Some country-specific quirks: Iran's DST schedule has changed multiple times. Russia abandoned DST in 2014. Egypt brought DST back in 2023. The calculator reads the latest IANA database, so its timezone math is current as of the IANA version your browser shipped with.
Dates near the DST switchover are tricky. The 'spring forward' moment skips an hour (2 am-3 am doesn't exist on that day in DST-observing zones); the 'fall back' moment repeats an hour (1 am-2 am happens twice). The calculator handles this automatically by using the IANA-defined wall clock convention - input 2:30 am on a spring-forward day and the calculator picks the unambiguous interpretation.
9 am IST on a Tuesday in February = 10:30 pm Monday in San Francisco (PST, UTC-8) = 1:30 am Tuesday in New York (EST, UTC-5) = 3:30 am in London (GMT, UTC+0). Once US DST kicks in (March), the same 9 am IST = 11:30 pm Monday in SF (PDT, UTC-7) - one hour later in US.
5 pm IST = 7:30 pm Singapore (SGT, UTC+8) = 9:30 pm Sydney (AEST, UTC+10, southern winter). In southern summer (DST in Sydney), the same 5 pm IST = 10:30 pm Sydney (AEDT, UTC+11). The 30-minute IST offset means India calls don't align cleanly with Asia-Pacific business hours - a fact that anyone working with both regions learns the hard way.
It uses the browser's built-in Intl.DateTimeFormat backed by the IANA timezone database - the same data that drives macOS, Linux and most server software. The math is exact and DST-aware.
Yes. The IANA database encodes DST rules for every timezone and the calculator applies the correct offset for the specific date you input.
India has run on a single timezone (IST, UTC+5:30) since 1947, with no DST. The geographic spread of the country (Gujarat to Arunachal) makes DST less impactful than in higher-latitude countries.
Because India's UTC+5:30 doesn't align with most other countries' whole-hour offsets, India-international meetings always end on weird half-past times. Nepal at UTC+5:45 is even more unusual.
Yes for any date after the IANA database was started in 1970. Pre-1970 dates can be ambiguous because timezone definitions varied historically.
Yes. Add as many target zones as you need - useful for scheduling meetings with team members in different countries.
Conversion math is exact for unit families that share a base - every length unit can be expressed in metres, every weight in kilograms, every temperature in kelvin. The only real decisions are precision (how many decimals to display) and rounding (banker's rounding vs round-half-up). This converter exposes both. For currencies and crypto we pull live rates because they change every minute; for everything else the math works offline.
Indian land units (gaj, ground, bigha, acre, hectare) are wired into the area converter alongside global ones - useful for property listings and government records. The MB-to-GB converter handles the decimal-vs-binary distinction (1 GB = 1,000 MB in storage marketing, but operating systems display 1 GiB = 1,024 MiB) so you stop wondering why your '2 TB drive' shows up as 1.81 TB in Windows.
The Time Zone Converter is part of the Converters suite on Online Calculator Tools, alongside 6 related calculators. All tools share the same UI patterns, the same privacy-first rendering (nothing is sent to a server), and the same commitment to showing the formula and assumptions behind every result.
