Use the free Time Zone Converter below: your data never leaves your browser — all work happens on your device, and nothing is uploaded to any server.
What the time zone converter does
Working out what time it is somewhere else should be simple, but daylight saving, half-hour zones and date changes make it easy to get wrong by an hour or even a whole day. This free time zone converter does the maths for you, in your browser, using the built-in Intl time zone database. You pick a date and time, pick where that time is, and pick where you want to know the time, and it shows the converted time with the right offset for that exact date. Nothing is sent to a server, and nothing you type is stored.
Below the converter you will also find the current time in major cities around the world, from New York and Mexico City to London, Dubai, Kolkata, Singapore, Tokyo and Sydney. That table updates from your own device clock each time you convert, so it is a quick way to check several places at once before a call or a flight.
How to use it
Pick a date and time in the first box. This is the time you already know, for example the start of a meeting in your city. Then pick the time zone that time belongs to, and pick the time zone you want to convert into. Press Convert and the big result shows the converted time. Press Use current time if you want to convert right now instead of a future time: the tool fills in the current date and time from your device.
Read the offset line under the result too. It tells you roughly how many hours apart the two zones are on that date, with daylight saving already included. That line is useful when you are scheduling a regular meeting, because the gap between two cities can change by an hour when one of them moves its clocks and the other does not.
Why time zones go wrong
Most mistakes come from three causes. First, daylight saving starts and ends on different dates in different countries, and some countries do not observe it at all. A gap that is five hours in January can be four hours in July. Second, a few zones are offset by half an hour or even 45 minutes, such as India at five and a half hours ahead of London in winter, so rounding to whole hours fails. Third, crossing the International Date Line changes the date, so a Monday evening call in Los Angeles can be a Tuesday morning call in Sydney.
Converting by hand with a fixed offset table ignores all three problems, because the offset depends on the date. That is why this tool uses your browser Intl database, which knows the real rules for each zone on each date, including historical changes. If your browser is up to date, its zone data is up to date too.
A worked example
Suppose you have a meeting at 3 in the afternoon in New York on 15 January, and you want to know the time in London. Enter 15 January at 15:00, choose New York as the source and London as the destination, and convert. In January the answer is 8 in the evening in London, a five-hour gap. Do the same for 15 July and the answer is still 8 in the evening, because both cities observe daylight saving, but the gap stays five hours. Now try New York to Sydney in January: 3 in the afternoon in New York is 7 in the morning the next day in Sydney, a sixteen-hour gap and a date change.
Common questions
Does the tool handle daylight saving? Yes. It uses the browser Intl database, which applies the daylight saving rules for the exact date you enter, not a single fixed offset.
Why does the gap between two cities change during the year? Because their clocks change on different dates, or one city changes and the other does not. Always convert for the actual meeting date, not for today, when you schedule ahead.
What about half-hour zones? They are included. Zones like Kolkata, Adelaide and Kathmandu are handled by the same database, so their half-hour and 45-minute offsets come out correctly.
Can I trust it for flight times? For planning, yes, but always confirm with the airline. Flight times use local times at each airport, and airports near a zone border or with unusual local rules can surprise you.
Limits of this tool
This converter works with the time zone data in your browser. If your browser or device is very old, its zone rules may be out of date, especially for countries that recently changed their rules. It also covers major cities rather than every small zone in the world. For critical scheduling, confirm the converted time with the other person once, and then save it in both time zones in your calendar.
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