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Time Zone Converter

Convert a time between two zones.

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Questions

Why does the date matter for a time zone conversion?

Because the difference between two zones is not a constant. London is five hours ahead of New York for most of the year but four for two weeks in March, because the two change their clocks on different dates. Anywhere one side observes daylight saving and the other does not — London and Tokyo, say — the gap moves by a full hour twice a year. A converter that ignores the date is wrong exactly when you need it: scheduling something on the far side of a changeover.

Does EST mean the same thing all year?

Strictly, no. EST is Eastern Standard Time, a fixed UTC−5 used only in winter; from March to November the same clocks read EDT, an hour ahead. In practice almost everyone writes EST to mean 'the time in New York' regardless of season, so that is how this tool reads it. The strict reading would give an answer that is wrong for eight months of the year, which is not what anyone typing it wants.

Which CST do you mean?

US Central Time, covering Chicago, Dallas and Winnipeg. CST is also China Standard Time, and the two are fourteen hours apart — the single most dangerous abbreviation in scheduling. China Standard Time is listed separately in the picker, so you can choose deliberately rather than discover the difference on the day.

What does the overlap line mean?

The hours that fall inside a nine-to-five day in both places at once. It is usually the question behind the conversion — not what time it is there, but when you can both realistically be at a desk. For some pairs, such as Los Angeles and Singapore, there is no overlap at all, and knowing that up front saves a round of proposed times that all fail.

Are half-hour zones handled?

Yes. India is UTC+5:30, and Newfoundland, parts of Australia and a few others are also offset by something other than a whole hour. The conversion works in minutes throughout rather than hours, so those come out right, including when the extra thirty minutes pushes a time over midnight into the next day.

How it works, and more about time zone converter

How it works

  1. Pick the two zones. Choose the zone you are converting from and the one you are converting to. The list uses the abbreviations people actually use — EST, PST, GMT, IST.
  2. Set the date and time. It starts on now. Change the date if you are scheduling ahead, because the difference between two zones is not the same all year.
  3. Read the result. You get the converted time, whether it lands on another day, the current offsets, and the hours when both places are inside a normal working day.

Why the answer depends on the date

The difference between two time zones is not a constant, and that is the single thing most converters get wrong. London is five hours ahead of New York for most of the year and four for about two weeks in March, because the two places change their clocks on different weekends. Where one side observes daylight saving and the other does not — London and Tokyo, Paris and Mumbai — the gap moves a full hour twice a year and never settles.

So this asks for a date as well as a time, and starts on today. If you are booking something for next month, change it: the conversion for a date on the far side of a changeover is not the conversion for today.

Abbreviations are not offsets

EST is, strictly, Eastern Standard Time — a fixed UTC−5 that New York only uses between November and March. For the rest of the year the same clocks read EDT. Almost nobody means that distinction when they write EST; they mean the time in New York. This tool follows the common usage, because the strict reading produces an answer that is wrong for two thirds of the year.

The one to be careful with is CST, which is Central Time in North America and China Standard Time in Asia — fourteen hours apart. Both are in the list, separately, so the choice is yours rather than a coin flip.

The question behind the question

Most conversions are not really about what the clock says somewhere else. They are about whether a call can happen. So alongside the converted time you get the window when both places are inside a normal working day — and, for the pairs where there isn’t one, a plain statement that somebody is going to have to take it early or late. Los Angeles and Singapore share no office hours at all, and finding that out before proposing three times that all fail is worth more than the conversion itself.

What this does not do

It converts between two zones. If you are trying to find a slot that works across three or more, a list of pairwise conversions is the wrong shape for the problem — the meeting planner shows a whole day across every zone at once, which is the view that actually answers it. Historical dates before the current daylight-saving rules were adopted are also outside what this handles reliably; it uses the rules in force now.