Time Zone Converter

A worked example

9:00 AM in Kolkata (UTC+5:30, no daylight saving) is 03:30 UTC. In New York that is 10:30 PM the previous evening in January, when the city is on UTC−5, but 11:30 PM in July, when daylight saving puts it on UTC−4. London shows 03:30 in January and 04:30 in July for the same reason. The gap between two cities can change by an hour through the year, so convert for the date of the event, not for today.

Use city zone names, not offsets

Choose a named zone such as Asia/Kolkata or America/New_York rather than a fixed offset. A name carries the daylight-saving rules for that place, including past rule changes, so the same name converts a January date and a July date correctly. A fixed offset like UTC−5 cannot, which is why a meeting booked with one is often an hour out after a clock change.

Names come from your browser's time-zone database, so older names such as Asia/Calcutta and newer ones can both appear and mean the same place. If a city is missing, pick another city in the same zone.

Dates near a clock change

On the day clocks change, one local hour is skipped in spring and one repeats in autumn, so a wall-clock time inside that hour can be ambiguous or not exist at all. If you are converting a time within a couple of hours of a changeover, check the result against the UTC line, or move the time slightly outside the changeover window to avoid ambiguity.

The UTC line is the reliable way to confirm a result: two people reading the same UTC instant always agree, even when their local clocks have different offsets.

When to use it

It is built for one-off conversions — a call across continents, a webinar time, a flight arrival — not for finding the best overlapping hours across many cities. For several participants, convert the same instant into each zone in turn and share the UTC time alongside local times so nobody has to guess.

What you can use it for

• Schedule a meeting across countries
• Convert a support call time to your local timezone
• Check the UTC instant behind a local wall-clock time
• Compare business hours between regions

How it works, step by step

1. 1

   Pick date and time

   Enter the wall-clock time you want to convert.

2. 2

   Choose source zone

   Select the timezone that time is written in.

3. 3

   Choose target zone

   Select where you want to read the time.

4. 4

   Read UTC

   Use the ISO output when you need an exact instant.

Frequently asked questions

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