Time Zone Converter

What is a time zone converter?

A time zone converter takes a date and time in one place and works out what that same moment looks like somewhere else — what a New Yorker calls 2 p.m. is already the middle of the night in Singapore, and the clock reading alone does not tell you that. This one reads the time zone database your browser already ships, the same IANA database behind almost every phone and computer, 418 zones deep, instead of carrying its own copy. The rules it applies are whatever your browser currently has installed, not a table that can quietly go stale.

One thing did have to be added by hand, and it is a surprising one: UTC is not in that list. The browser's list is geographic zones only — no UTC, no “Etc/” entries at all — even though the browser accepts “UTC” perfectly well when you pass it in. A converter that trusted the list would have shipped without the single zone people most want to compare against.

Type in a date and time, pick the zone it is in, then add every city or region you need to check against it — a client call in London, a release window in Tokyo, a flight landing in Los Angeles. Each becomes a row showing the local date and time there, the UTC offset, and what that zone calls itself at that moment, whether that is EST, EDT, or a bare GMT+5:45.

How to convert a time between zones

1. Set the date, time, and From zone. The date and time fields start on the current moment and the From zone starts on your own detected time zone, so you can leave every field alone if you are just asking what time it is right now — or change any of them to work from a specific moment instead.
2. Add the zones you want to compare. Each zone you add becomes its own row: its local date and time at that moment, its UTC offset, what it calls itself right then (EST, EDT, GMT+5:45), and — when it differs from the From zone — whether that is the previous day or the next day there.
3. Copy the whole comparison. The Copy button grabs every row at once, ready to paste into an email or a meeting invite. If the date and time you typed falls inside a daylight-saving change, a message says so specifically, since that is exactly the moment a plain clock reading stops being reliable.

The two days a year a clock time is not a single moment

Twice a year, in places that observe daylight saving, a clock reading and a moment in time stop being the same question. When the clocks go forward, an hour gets skipped entirely: in New York on 8 March 2026, the clock goes from 01:59:59 straight to 03:00:00. Every minute from 02:00 to 02:59 simply never happens that day — there is no moment on the timeline that a clock in New York would ever show as 02:30. Type that time in and the honest answer is not a converted time, it is that the reading does not exist.

When the clocks go back in autumn, the opposite problem shows up: an hour repeats. In New York on 1 November 2026, 01:30 happens twice — once at UTC-04:00, while daylight saving is still in effect, and again an hour later at UTC-05:00, once it has ended. Both are real, and neither is more correct than the other, so a converter that just picks one is quietly guessing. This tool shows both answers instead, because for anyone relying on the result — confirming a call time, checking a log timestamp — the gap between the two answers is an hour, and an hour is exactly the kind of mistake that matters.

Both of those dates were read out of the browser's own database by scanning the year for offset changes, rather than typed from memory, and the skipped window was then checked minute by minute.

Offsets that aren't whole hours, and days that don't line up

Not every time zone sits on the hour. Kathmandu is UTC+05:45 and Chatham Island is UTC+12:45, and the daylight-saving shift itself is not always a full hour either — Lord Howe Island moves its clocks by exactly half an hour, so its skipped window each spring is 30 minutes wide, not 60. The comparison rows show these offsets as they are rather than rounding them into something tidier.

The date is often the part that actually matters. Late evening in New York can already be the following afternoon in Tokyo, and a schedule built without checking that lands a meeting on the wrong day entirely. Every comparison row says outright whether it is the previous day or the next day there, so that question is answered before you even look at the clock.

A smaller caveat on the names: the short abbreviations the browser reports are not unique worldwide — several countries have used “CST” for entirely different offsets — and plenty of zones have no widely recognised abbreviation at all, so the browser just reports something like GMT+11. That is why every row shows the numeric offset alongside whatever name the zone gives itself.

Why is it free?

Every conversion runs in your browser, using the time zone data already built into it. There is no server involved, so there is nothing to upload, no account to create, and no result to watermark.

The one honest caveat: the accuracy of any date depends on your browser's time zone rules being current. Governments change daylight-saving rules sometimes with only a few months' notice, and a browser that has not updated will apply the old ones. That is true of nearly every tool built on the system's time zone database — worth saying plainly rather than implying the answer is fixed forever.