Timezone Converter

Pick a date, a time and a source timezone, and see the equivalent wall-clock time across a curated list of major timezones — including whether it lands on the previous or next day. Built on the browser's own IANA timezone database, so DST transitions are handled correctly.

20 major timezones at once

Correct DST handling via the browser's IANA database

Shows day-before / day-after clearly

Any zone can be the source

Runs fully client-side

How to convert a time across timezones

Set the date and time

Enter the date and time as it reads on a clock in the source location — not converted to your own time first.

Choose the source timezone

This is the timezone the date and time you just entered actually belong to.

Read the converted times

Every other zone updates to show the equivalent moment, with a marker if it falls on the previous or next day there.

Why this needs the browser's timezone database, not arithmetic#

A timezone offset is not a fixed number. America/New_York is UTC-5 in January and UTC-4 in July, because of daylight saving time — and the date the switch happens changes from year to year, and not every country observes it. Hardcoding "New York is UTC-5" is correct for roughly half of the calendar and silently wrong for the other half.

This tool uses the Intl API built into every modern browser, which ships the same IANA timezone database (America/New_York, Europe/Madrid, and so on) that server-side systems use. The offset for any given date is looked up, not calculated — so DST transitions, and the rare cases where a country changes its rules entirely, are handled correctly without this tool needing to track any of it.

The wall-clock time versus your own timezone#

Enter the time exactly as it would read on a clock in the source location — "3pm in New York" means typing 15:00 and selecting America/New_York, regardless of what time it currently is where you are. This trips people up because most date pickers implicitly assume "your" timezone; this tool asks you to be explicit about whose clock the number belongs to.

Why the day sometimes changes#

A large enough offset means the equivalent time in another zone genuinely falls on a different calendar date. 3pm in New York on a Tuesday is already 4am Wednesday in Tokyo — not a bug, just what a nine-hour-plus offset does to a time near midnight on the other side. Each zone shows whether it lands a day before or after the source date so this does not get missed when scheduling something across a date boundary.

Frequently asked questions

Does this tool account for daylight saving time?

Yes, correctly and automatically — it uses the IANA timezone database built into your browser, the same one used by servers, which looks up the actual offset for the specific date you entered rather than assuming a fixed offset per zone.

What time should I enter — mine, or the source location's?

The source location's. If you mean 3pm in New York, enter 15:00 and select America/New_York as the source zone, regardless of what time it currently is in your own location.

Why does one of the converted times show a different date?

Large timezone offsets can push a time across midnight into the next calendar day, or back into the previous one. This is expected — the tool marks each zone that lands on a different date from the source so it is not missed when scheduling.

Is my data sent anywhere to convert the time?

No. The conversion runs entirely in your browser using the Intl API. Nothing is transmitted, logged or stored.

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